LITHUANIAN UNIVERSITY OF HEALTH SCIENCES
MEDICAL ACADEMY
DEPARTMENT OF PEDIATRIC ENDOCRINOLOGY
BY
REFAAT YEHYA
FACULTY OF MEDICINE
COURSE VI
GROUP 31
PREVALENCE AND CLINICAL MANIFESTATIONS OF
SEVERE PRIMARY IGF-1 DEFICIENCY IN LITHUANIA
The programme of studies: medicine
Supervisor: prof. Rasa Verkauskienė
Department and Institute of Endocrinology Medical Academy
Lithuanian University of Health Sciences
Table of contents
1. Title page (pg.1)
2. Table of contents (pg.2)
3. Summary (pg.3-4)
4. Acknowledgments (pg.5)
5. Conflicts of interest (pg.5)
6. Ethics Committee Approval (pg.6)
7. Abbreviations (pg.7)
8. Terms (pg.7)
9. Introduction (pg.8)
10. Aims and Objectives (pg.9)
11. Literature Review (pg.10-14)
12. Methodology and Methods (pg.15-16)
13. Results and their discussion (pg.17-23)
14. Conclusion (pg.24-25)
Summary:
Name and Surname: Refaat Yehya
Title: Prevalence and clinical manifestations of severe primary IGF-1 deficiency in a single reference center.
Aim and objectives: The purpose of this retrospective study is to study the prevalence of insulin like growth factor-1 (IGF-1) deficiency among children referred to Lithuanian
University of Health Sciences (LUHS) hospital Kaunas clinics because of short stature during the period of 2012-2015. In addition, we aim to study their auxological characteristics,
glucose and hormonal levels and lipid profile, parental information (parental height), and prenatal information (birth length, birth weight, gestational age at birth) to assess any correlation between these and severe primary IGF-1 deficiency (SPIGFD).
Methodology and participants: Data were collected and analyzed from a cohort of 135 children aged 2-17 years who were investigated for short stature (SS) in Pediatric
Endocrinology Unit of Hospital of Lithuanian University of Health Sciences (LUHS) Kauno klinikos from January 2012 to December 2015.
The SPIGFD diagnostic criteria used in our research were 1) normal or high level of growth hormone (GH) secretion during GH stimulation test (more than 20 mU/l), 2) IGF-1 level < -2 standard deviation (SD) of the normal range for the age and gender, 3) short stature with height < -3 SD below the mean for age and gender, 4) exclusion of all secondary IGF-1 deficiency due to factors such as malnutrition, steroids, chemotherapy, skeletal dysplasia, liver disease.
Then IGF-1 generation test was done. An increase of IGF-1 by less than 50 % will confirm SPIGFD in the patient.
The auxological measurements (height, sitting height, head and waist circumference, bone age delay), hormonal levels (prolactin, alkaline phosphatase (ALP), IGF-1, GH, insulin) and lipid profile (high density lipoprotein (HDL), low density lipoprotein (LDL), triglycerides (TG), cholesterol) were analyzed for patients of suspected SPIGFD.
Results: Out of 135 patients included, 37 (27.4%) were diagnosed GH deficiency. We identified 10 patients who matched our criterion for IGFD (7.4%). Four patients of 10 were excluded because they had fused growth plate and 1 patient refused to attend. IGF-1
generation test was performed for 5 patients. The IGF-1 increment less than 50% was detected in 4 patients (4/135; 2.96%). Patients’ mean age was 8.49±1.35 years and height
-decreasing. All indentified patients with IGFD were born in full term (39.5±0.86 gestation week), birth weight/length were normal (-0.76±1.18 SD; -0.13±1.03 SD) except one of them 2.65; -1.7 SDS). Target height of patients was lower than mean of general population (-1.79±0.48 SDS). All patients with IGFD had delayed bone age (-2.24±0.88 years) and normal sitting height/height ratio 0.547±0.01 (1.375±0.7SDS).
Fasting insulin levels were within normal limits for age. Regarding to the lipid profile, we can see that cholesterol and triglycerides levels are normal, but all patients had decreased HDL and 2 of them increased LDL, which confirmed dyslipidemia.
Conclusions: Following up these patients is necessary for either to prove new findings and follow their growth during life or to contradict previous ones like insulin resistance, diabetes, body fat formation and delayed puberty in patients with IGFD.
Acknowledgements A lot of time, work and effort were given to make this research
possible. Thank you to everyone who gave us support and advice. I would like to thank Prof. Rasa Verkauskiene and Dr. Ruta Navardauskaite who helped me and adviced me throughout the whole research.
Ethics Committee Clearance : Nr. BEC-MF-48 Date 2015-10-14
Abbreviations list
SS (short stature), GH (growth hormone), IGF-1 (insulin like growth factor-1), IBD
(inflammatory bowel disease), IGFD (insulin like growth factor deficiency), SPIGFD (severe primary insulin like growth factor-1 deficiency), ALP (alkaline phosphatase), BMI (body mass index), ALS (acid labile subunit), LS (Laron syndrome), GHRH (growth hormone releasing hormone), GHIH (growth hormone inhibiting hormone), GHR (growth hormone receptor), GHD (growth hormone deficiency), GHI (growth hormone insensitivity), rGH (recombinant growth hormone), IGFBP-3 (IGF binding protein 3), LV (left ventricle), BAT (brown adipose tissue), SD (standard deviation), HOMA-IR (homeostatic model assessment-inulin resistance), SGA (small for gestational age), AGA (appropriate for gestational age), LDL (low density lipoprotein), HDL (high density lipoprotein)
Key words
GH, IGF-1, IGF-1 deficiency, GH insensitivity, Laron syndrome, somatomedin, IGFBP-3,
Introduction :
Short stature (SS) is present in around 3-5 % of all children. A lot of causes and diseases can be attributed to this abnormality. Growth hormone (GH) deficiency and GH
insensitivity/IGF-1 deficiency all can be reasons of a person having short stature.[1]
In summary, IGF-1 is secreted by the liver, which is stimulated by GH to do so. The latter is secreted in a pulsatile manner by the anterior pituitary gland and is controlled by the
hypothalamus.[2]
IGF-1 deficiency can be primary and caused by defect in GH receptor due to genetic mutation which tends to make it insensitive to the hormone and hence unable to stimulate liver cells to secrete IGF-1 so that IGF-1 deficiency will develop.[3] Secondary IGF-1 deficiency (IGFD) can be due to other reasons like chemotherapy, steroids, celiac disease, inflammatory bowel disease (IBD) (Crohn disease and ulcerative colitis), malnutrition and liver diseases.[4]
GH and IGF-1 stimulate development and growth. The deficiency of any of them will lead to short stature. [5]
IGF-1 roles are to promote height, vision, hearing and has effects on head and waist circumference in addition to metabolic effects on glucose, and lipids.[6]
A lot of characteristics affecting the body related to IGFD will be studied in this research like height, sitting height, body mass index (BMI), bone mass and age, head and waist
circumference and some hormonal and metabolic profiles like lipid panel, glucose, insulin, prolactin and alkaline phosphatase (ALP) in relation to GH and IGF-1 level.
The diagnostic criteria of IFGD in our research is stated as a person having 1) short stature as height less than 3 standard deviation of the average height in people in the same age group, 2) IGF-1 less than 2 standard deviation of the average level of people in the same age group and gender, 3) normal or high GH level. In addition, all secondary causes stated before have to be excluded.[7]
For children being short in stature is an indicator of decreased health quality in some areas. A patient with this disorder will be unable to achieve full growth and development of his/her body parts and organs. He/she will have fragile bones and be more prone to fractures than others. [8]
Thus, the importance of this research is to study the clinical manifestations of this disorder and to provide its prevalence in Lithuania.
Aim & Objectives: The purpose of this retrospective study is to collect data on children with
short stature and find out the how many of them is caused by severe primaryIGF-1
deficiency. Throughout our data collection, we encountered patients having GH deficiency as the cause of their short stature; thus, they started treat with recombinant GH and treatment response we evaluated less after one year of treatment. Add to this, we will study some clinical manifestations of this disorder and compare them with previous publications results made on this topic.
In this research, the characteristics under investigation are auxological (height, sitting height, parent’s height, BMI, head and waist circumference), prenatal information, hormonal and biochemical (prolactin, ALP, IGF-1, GH, insulin), in addition to glucose and lipid profile. These measurements and tests will be done on patients suspected for this disorder after collecting all the data necessary according to the diagnostic criteria stated before taking into consideration excluding all secondary factors that can influence our study results such as puberty, medicines, and some other diseases.
This study can help in finding new clinical characteristics and confirming old ones on a certain sample of population (Lithuanian origin) not studied previously for this kind of disorder which can lead to shortening of the gap of information in this field due to lack of patients worldwide. Our hope is to develop a clearer picture and better understanding of this topic.
Literature Review:
Overview
One of the main important health goals is to achieve growth and optimal bone mass because it affects the fragility of bones and risk of fractures later in life. Bone mass development is done by interplay of many hormones like growth hormone (GH) and Insulin like growth factor 1 (IGF1) which are necessary for bone growth in all directions.[8] Short stature is seen
in 3-5 % of all children. It can be caused due to many different diseases like GH deficiency, multiple pituitary hormone deficiency, GH insensitivity, primary acid labile subunit (ALS) deficiency, and IGF1 resistance. [1]
Definition
Our main topic is GH insensitivity or severe primary IGF1 deficiency known also as Laron syndrome (LS). It is an autosomal recessively inherited disease caused by many types of mutations or deletion in the genes that codes for GH receptor or by post receptor defects.[9] This defect will make the patient unable to produce IGF1 and thus will lead to dwarfism. These patients have high level of GH in serum but low level of IGF1. [10] The term “primary IGF1 deficiency” is used by Rosenfield to describe these patients. [6]
History and discovery
Salmon and Daughday tried an experiment in 1957 with hypophysectomized rats and found uptake of 35S-sulfate by costal cartilage after stimulation by normal serum and not GH. They deduced then that the serum contains a substance “sulfation factor” named somatomedin (later named IGF-1 in the 1980s) which plays a role in this growth process and is dependent on GH.[11,3] Laron syndrome was first discovered by Zvi Laron in 1959 in 3 siblings having
severe short stature.[12] The turning point in this field was the synthesis of recombinant
human IGF1 in late 1980s in addition to cloning and characterization of GH receptors that lead to better understanding of pathophysiology.[13]
Epidemiology
Around 250 cases of severe primary IGF1 deficiency (IGFD) are discovered in the world, mostly in countries of Middle East, Mediterranean, South Asia and Ecuador. In a study done in France with a large cohort of patients (2496) having slow stature growth, 30 patients were having IGFD with a prevalence of 1.2 %.[7]
Physiology
The anterior pituitary secretes GH in a pulsatile fashion. This secretion is controlled and regulated by the hypothalamus secretion of growth hormone releasing hormone (GHRH), which has a stimulatory effect on GH, and growth hormone inhibiting hormone (GHIH) that has an inhibitory effect on its secretion. GH is a single chain polypeptide that binds on GH receptor (GHR). It has 2 locations to execute its function: liver and growth plate. GH
stimulates the liver to secrete IGF1, IGF binding protein 3 (IFGBP3) and ALS in addition to the proliferation of prechondrocytes and production of IGF1 at the growth plate. Thus, GH has a very important role in growth.[5]
The liver expresses numerous GHR which are composed of large extracellular domain that binds GH and produce dimerization, a transmembrane domain that attach the GHR to cell surface and intracellular domain which plays a role in GH signaling. GH normally binds to the receptor to induce conformational change and activates it.[13] IGF1 then binds to specific high affinity receptors to produce cellular proliferation and differentiation. It is regulated by IGF binding proteins (IGFBP) as well.[11]
Pathophysiology and genetic defects
Many defects of IGF1 system can lead to IGFD. GH receptor defects include: extracellular transmembrane and intracellular. GH signal transduction can also be defected or IGF 1 gene can be mutated that lead to deficiency or inactive IGF1.[13] In 1984 the defect of GH
insensitivity (GHI) was identified to be on GH cellular receptor. In 1989 the genetic defect was described as deletion of exons 3,5,6 in some patients with LS.[3] Later, more than 70 GHR mutations were found and include missense or non sense mutations, insertion, deletion or splice site mutations. After analysis, result was: R217X mutation of GHR gene is
homozygous on chromosome 12.[9,14]
Insulin-like growth factor 1 (IGF1)
It is a single chain composed of 70 amino acids and 3 intermolecular disulfide bridge with a molecular weight of 7649 Daltons. Its structure is 50% similar to proinsulin.[14] ALS and 80% of IGF1 are produced by hepatocytes. IGFBP3 is produced by kupffer and sinusoidal
endothelial cells.[11] Connective tissues of 14 other organs contribute to the production of the other 20% of IGF1 (e.g. perichondrial cartilage, septa and connective tissue enveloping most organs, eye sclera).[14]
IGF1 can be present in blood in 3 forms: 75% of it is bound to IGFBP3 and ALS in a ternary complex while the remainder is bound only to lower molecular mass IGFBPs and less than 1% is present in free form.[8] Free form of IGF1 has half life of 4 hours, however, the ternary complex has half life of 18-20 hours.[6] The latter cannot cross the capillary barrier and is present only in intravascular space. Thus, the role of IGFBP3 and ALS is to increase half-life of IGF1 and to keep it in intravascular space for longer time to get access to target tissues. There are 6 IGFBPs whose functions are, in addition to what stated earlier, to prevent IGF induced hypoglycemia. IGF1 level is low at birth but increases gradually and peaks during puberty and then decreases gradually with age to reach 150 ng/ml at age 50 and 100 ng/ml at age 80.[5,15]
IGF1 has a major role affecting human height, length of life, sight and hearing.[14] It also stimulate glucose uptake, glycogen synthesis, amino acid transport and increase in net protein synthesis.[6] IGF1 plays an important role in development of inner ear, ovarian follicles, brain and head circumference.[15,16,17] IGF1 is a critical factor in bone growth in longitudinal way and in width. It is proved in a study published in 2012 that absence of IGF1 will lead to 40% reduction in bone size as well as 87% decrease in bone mineral content of the femur. Thus IGF1 has a central role in skeletal growth of the individual.[8]
Characteristics and manifestations
Patients with GHIS have normal birth length and weight; however, postnatal growth is abnormal and resulting to an extreme short adult. Decreased amount of muscle mass with a lot of adipose tissue and relative obesity are seen. Facial bone growth and fontanel closure are delayed. Shallow orbits, saddle nose, blue sclera, sparse hair growth, narrow larynx, small gonads and very high pitch voice can be noticed. Teeth growth is delayed and might be defective as well. Acromicria is present with small hands and feet. The skin is thin. Puberty is delayed more in boys than in girls and achieved without pubertal growth spurt. Patients vary from normal intelligence to severe mental retardation. Add to this, micropenis, undescended testes and sleep apnea can be seen in some patients.[9,12]
Bones and skeleton: Patients have small skeleton, narrow spinal canal, delayed bone age and
limited elbow distensibility. They also have small vertebral bodies and pelvis in addition to narrow lumbar canal and small interpedicular distance, which indicate spinal stenosis.
Moreover, high rate of anterior osteophytes in lumbar spine can be seen. Bone age is delayed and final stature is between 108 cm and 136 cm in women and between 116 cm and 142 cm in men.[10]
Fat distribution and obesity: According to a study published in 2006, patients with IGF1
deficiency are more obese than control group. Females have 60% fat in their body comparing to only 29% in control group. Fat is seen to be distributed more in arms than legs and
trunk.[18]
Head and brain: patients having IGFD have decreased head circumference and brain size,
mostly below 2 standard deviation of mean normal.[17]
Inner ear: Sensorineural hearing loss, lack of acoustic stapedial reflexes and auditory
hypersensitivity are found in some patients with IGF1 deficiency. IGF1 has a big role in developing the inner ear. It inhibits apoptosis of hair cells and is involved in cochlear vestibular ganglion neurogenesis in inner ear.[15]
Heart: Patients with LS have small left ventricular diastolic and systolic dimensions. Left
ventricle (LV) mass is small as well.[19] In addition, cardiomicria, diminished left ventricular output and reduction in maximal aerobic capacity are noticed.[9]
Some studies are done on mice and many findings were noticed by morphological analysis of organs: lower biological age for organs and more brown adipose tissue (BAT) around organs is seen which indicate low age of organs.[20]
However, LS has few good characteristics and outcomes. It increases life span of individuals. People with LS in Ecuador live till around 78 years with the main reason of this finding is that LS protects individuals from cancer, a main cause of death.[21] In a study published in 2011, none of the 230 individuals with LS developed cancer.[22]
Diagnostic criteria
In Europe, criteria were set to diagnose SPIGFD: 1) height < -3 SD, 2) IGF1 < -2.5 SD, 3) normal or elevated GH, 4) exclusion of chronic treatment by steroids, hypothyroidism, chemotherapy, liver diseases, IBD, untreated celiac disease and malnutrition.[7]
Nutritional status should be evaluated because malnutrition can cause IGFD. According to studies done previously, not only GH is needed to secrete IGF-1 but good nutrition is required as well because it has been showing that nutritional deficiency can lead to IGF-1 deficiency. [4]
Treatment and side effects
The first treatment of GHI was in 1992 in Israel where 5 children were treated for 3-10 months and 27 children for 2-12 months.[3] The rhIGF1 is a recombinant human IGF1 analog
adolescents. The starting dose is 0.04-0.08 mg/kg 2 times per day. The dose can be increased up to 0.12 mg/kg.[14] The rhIGF increases linear growth velocity from 3.6 cm/year to 8.4 cm/year during first year of treatment and it decreases the body fat and maintains LV dimension and function.[9,11] Same criteria presented to diagnosis of GHI should be met to start treatment with rhIGF1.[4] This therapy was approved by Food and drug administration
(FDA) in 2005 and European Agency for Evaluation of Medical Products (EAEM) in 2007.[5] As any treatment, side effects are present with hypoglycemia being the most common. Other adverse effects include tonsillar or adenoidal hypertrophy, intracranial hypertension or papilledema, headache and injection site reactions.[9,6] Several parameters should be checked to assess efficacy of treatment: 1) good height velocity response ( >1 SD ) or between 7 cm and 11.4 cm; 2) good height response (height gain > 0.5 SD); 3) normal IGF1 levels.[7]
Other causes of Short stature (SS): GH deficiency
Other cause of SS is GHD. It can be due to trauma, infection, tumor, and radiotherapy that damage pituitary and hence GH is absent. Mostly it is idiopathic. Individuals with GHD have decrease GH and IGF1 which lead to growth failure and high pitch voice, doll face,
periabdominal fat, decrease muscle mass and acromicria.[1]
Future considerations
Some further studies can be done in this field to evaluate the result of treatment with 2 different doses of rhIGF1 and to protect treated patients from developing cancer later in life.[7,22]
Methodology and methods:
Subjects
Firstly, we performed a retrospective analysis of medical records obtained from the Lithuanian University of Health Sciences hospital Kaunas clinics. Data was collected and analyzed from a cohort of 135 children aged 0-17 years. Study will include all children who were investigated for short stature with GH stimulation tests in Pediatric Endocrinology Unit of Hospital of Lithuanian University of Health Sciences (LUHS) Kauno klinikos from January 2012 to December 2015. The performed patients were from whole Lithuanian territory.
The documentation reviewed included the GH peak during GH stimulation tests, a serum IGF-I levels, a height at examination day. Subnormal GH secretion in response to at least two provocative stimulation test (agents which have been used clinically to stimulate and assess GH secretion are insulin and/or with glucagon and/or with oral clonidine) is considered when GH maximum is below 20 mU/L (10 μg/L).
Secondly, if GH deficiency were detected, the therapy with recombinant growth hormone was started and then we evaluated growth data during first year of GH treatment (poor response of GH therapy is considered when growth velocity is less than 4 cm / year). Children with low basal IGF-1 concentration (2 SDS below average according age and gender), but normal/high GH response to stimulation and height less than 3 standard
deviations below the mean for the normal population were invited for IGF-1 generation test. Patients with skeletal dysplasia, confirmed genetics syndromes related with short stature, chronically malnourished, having liver diseases, untreated celiac disease, inflammatory bowel disease, who had received chemotherapy for cancer and patients with closed epiphyses were excluded.
IGF-1 generation test
The IGF-1 generation test was performed by prepared protocol in Department of Pediatric Endocrinology LUHS. The Protocol was prepared according a comprehensive study. (23-28)
The standard dose (33 μg/kg per day for 4 days, total 132 μg/kg) was used in IGF-1 generation test.
Patients for IGF-1 test were hospitalized for six days. Blood samples were collected after an overnight (on the second day) for subsequent analysis of basal IGF-1, insulin, prolactin, lipid panel and glucose.
The injection of growth hormone (Nutropin AQ® [somatropin (rDNA origin) injection]) is
applied subcutaneously for 4 days in the evening. The blood sample for IGF-1 is taken 12 hours after the 4th injection.
The growth hormone insensitivity or severe primary IGF-1 deficiency is confirmed, when ΔIGF-1 is less 50 .
The auxological measurements (height, weight, sitting height, head, waist and hip
circumferences), prenatal (birth length, weight, gestation weeks, parental heights) history were collected and bone age estimated (according to Greulych and Pyle) on the first day of hospitalization.
The measurements of hormones levels were performed in the Department of Laboratory medicine of LUHS. Immunoradiometric assays were used for IGF-I, prolactin, insulin; total cholesterol, triglyceride (Bayer reagents for enzymatic assays on a DAX autoanalyzer), HDL cholesterol (by phosphotungstic acid MgCl2 precipitation method) and blood glucose
concentrations. All methods were quality-controlled and accredited according to international standards.
Regarding close relationship between IGF-1 deficiency and insulin resistance, we calculated homeostatic model assessment (HOMA-IR) used formula: (glucose x insulin): 22.5; the
normal reference range for HOMA-IR is 1.7-2.0, value > 2 as threshold to determine insulin
resistance.[29]
All auxological measurements, diagnostic and therapeutic management were conducted by the same team of physicians and nurses.
Statistics
Data are displayed as mean SD unless stated otherwise. Paired t-test was used for
comparison of paired values, while one-sample t-test was employed for comparison of sets of standardized SDS data against the zero-value (birth weight, birth length, body height, body mass index), with statistical significance level set at 0.05. Correlation of two independent variables was evaluated by a linear regression test.
Results:
Fig 1: Scheme of the study
We started our data collection from 135 patients with short stature. After measuring the GH level, we found that 37 patients have low levels of GH and suffer from GHD, 10 of them have normal or high levels of GH and have the criteria needed for IGFD (-3SD in short stature and -2.5 SD of IGF-1 level). IGF-1 generation test was needed to confirm the
diagnosis on these patients; however, only 5 (1 small for gestational age and 4 appropriate for gestational age) got the test because 4 of them were excluded because they have reached final height and 1 patient refused it. We confirmed the disease in 4 out of these 5 patients after receiving the results of the IGF-1 generation test.
Fig 2: Distribution of short stature patients according causes
135
pa
tien
ts w
ith
shor
t
st
atu
re
GHD (n=37) IGFD (n=10) excluded due to epyphyseal fusion (n=4) excluded due to parental refusal (n=1) suspected IGFD (n=5) (1SGA, 4AGA) confirmed IGFD (n=4) non confirmed IGFD(n=1) Idiopatic short stature
(ISS) (n=88)
Prevalence of GHD and IGFD in short
stature (2012-2015)
Other GHD excluded
suspected non confirmed IGFD
This figure shows that short stature in 27 % of a 135 patients cohort study is attributed to GHD. Four percent of patients were suspected of having IGFD and after the IGF-1 stimulation test is done, 2.96 % are confirmed to have the disease and 0.74 % couldn’t be confirmed. The majority of the patients 65% have other causes of short stature. Note that 4% of the sample has been excluded later even though their lab results showed suspicions of having IGFD (1% due to parental refusal and 3% due to reaching puberty and bone plates were closed). We can finally say that IGFD is confirmed in 2.96% of all short stature children in Lithuania during the period of January 2012-december 2015. The prevalence of this
disease in Lithuania is considered relatively high compared to its prevalence in France where a study was done between 2004-2009 and shows only 1.2 % of the sample having confirmed IGFD (7). Although our study has a higher percentage (2.96%) but contains a lower number of patients suffering from this disease (4 patients) than the French study, which includes 30 patients out of 2496. This can be attributed to area and time. The fact that France is a bigger country and has a higher number of population than Lithuania and that study was done on a 5 years period affected the number of patients to be higher than ours but the percentage was less by more than half.
Analyses of GHD patients Table 1: GHD patients Number (boys, girls) Age (years; SD) Mean of height at start of rGH therapy (SD) Median of bone age retardation (years; min.-max. ) Growth velocity at 1st year of treatment (median±SD) 37 (30;7) 8.2± 3.7years (4.1- 14.4) -3.25±0.98 2.41 (0.74-5.54) 8.64±4.19 cm/year
During data collection, 37 patients out of 135 (30 boys; 7 girls) had GH < 20 mU/L and were diagnosed with growth hormone deficiency and then GH therapy was initiated. These
patients were aged between 4.1 and 14.4 years (average 8.2 ± 3.7). At the start of GH administration, the mean height SDS was -3.25 ± 0.98, with median bone age retardation of 2.41 years (max. -5.54, min. -0.74). GH replacement led to growth velocity 8.64 cm/year
during the first year of treatment. We can clearly see that the prevalence of GHD (37 patients) is much more than the rare IGFD. In addition, there is a clear point that shows us that males are more diagnosed with GHD than females.
Table 2: Laboratory and hormonal levels of the final 5 patients
Hormones # 1 # 2 # 3 # 4 # 5 Mean of confirmed IGFD GH peak (mU/L) 32.6 55.9 23.3 51.5 33.3 x Basal IGF-1 (nmol/L) 8.3 12.1 12.2 10.9 20.7 x IGF-1 on day 5 (nmol/L) 13 18.5 33.1 14.5 40.6 x IGF-1 (during IGF-1 generation test) 36.15 % 34.6% 58.37% 33% 49.01% x Prolactin (normal: 38-337 mU/l) 250 116 247 239 272 219.2±60.7 Fasting glucose (normal: 4.1-6.6 mmol/L) 4.86 3.84 3.56 4.59 4.32 4.40± 0.37 Fasting insulin (normal: 6-44 mU/L) 6 5.1 3 5.1 5.3 5.37± 0.36 HOMA-IR (normal < 2) 1.3 0.87 0.47 1.04 1.02 1.05± 0.15 ALP (normal: 0-526 U/L) 159 127 174 148 168 150.5±15.3 Cholesterol (normal: 0-5.5 mmol/L) 3.81 3.63 4.87 4.81 5.4 4.41 ± 0.72 HDL (normal: 1.22 1.41 1.37 1.15 1.91 1.42 ± 0.29
>1.55 mmol/L) LDL (normal: 0-2.59 mmol/L) 2.25 1.9 3.46 3.28 3.33 2.69± 0.62 Triglycerides (normal:0-1.95 mmol/L) 0.67 0.38 0.37 0.96 0.76 0.69± 0.20
After performing IGF-1 generation test on these 5 patients, (all of them have normal or high GH level), 4 of them got ΔIGF-1 less than 50 , which confirms IGFD. We found the lowest increase in Patients number 4 (33%), then patient number 2 (34.6 %), then patient number 1 (36.15 %) and finally patient number 5 (49.01%). Patient number 3 was the only one who has a difference more than 50% (58.37%) and cannot be confirmed of having IGFD. The
prolactin level and ALP were normal in all patients, which tells us that there is no proven correlation between them and IGFD.
This table shows us that the glucose level is lower than the normal range in patient number 2 and 3 (where only patient 2 is confirmed with IGFD); however, the mean value of glucose in all IGFD is normal. Moreover, insulin levels shown here are lower than the average in all patients except patient number 1 who has a borderline level within the normal range. If we check the mean of the 4 confirmed patients, we see that they have normal glucose but low insulin level. In contrast to a study published in 2015 which states that a decrease in the level of IGF-1 is associated with insulin resistance and increase risk of diabetes mellitus, our results shows no abnormal HOMA-IR results which indicate the presence of insulin resistance neither high level of glucose which indicates the presence of diabetes mellitus. This can be explained by the fact that our patients are not old enough to develop diabetes due to insulin resistance (average age is 8.49 years). But, the HOMA-IR index for the 4 patients having the disease are much higher than the index of the suspected one and are 3 of them above 1.0 which can lead us to think about a greater possibility to develop the resistance and the diabetes later in life in accordance to the findings of that previous study. (14)
In accordance to the lipid profile, we can see that cholesterol and triglycerides levels are normal in the contrary to the conclusion stated by a study done in 2006 which says that patients suffering from IGFD have hypercholesterolemia as a consequence of adiposity due to the absence of IGF-1. However, the mean level of LDL and HDL are quite abnormal which can lead us to develop a certain idea that these children are prone to have increasing
body fat with increasing cholesterol in the blood soon in their life. This correlate with the results in the research stated earlier. Up to this moment, to understand this contradictory result, we can say that being active during daytime and the overall physical activity of these children might have affected their body fat and decreased the cholesterol and triglycerides level just temporarily. It is important and necessary to follow these patients in their life and check again all these levels (lipids, insulin, glucose) to either confirm the results of the previous studies or contradict them with ours.
Table 3: Auxological characteristics of the final 5 patients
Characteristics # 1 # 2 # 3 # 4 # 5 Mean of suspected IGFD Mean of confirmed IGFD Gestational age 40 38 40 40 40 39.6 39.5±0.86 Birth length (SDS) - 0.15 - 1.7 - 1.37 0.12 1.21 -0.37±5.7 -0.13±1.03 Birth weight (SDS) - 0.67 - 2.65 - 1.825 0.6 - 0.33 -0.975±0.62 -0.76±1.18 Paternal height (SDS) - 0.76 - 1.76 - 0.47 - 2.18 - 1.25 -1.28±0.62 -1.48±0.53 Maternal height (SDS) -1.95 -1.15 - 2.11 - 1.47 - 1.55 -1.64±0.34 -1.53±0.28 Mid-parental height (SDS) - 1.26 - 2.5 - 1.19 - 1.95 - 1.45 -1.67±0.49 -1.79±0.48 Difference between child height and mid-parental height (SDS) - 2.21 - 0.67 - 2.43 - 2.12 - 1.65 -1.81±0.62 -1.66±0.61 Chronological age (years) 7.18 7.64 6.52 8.46 10.71 8.1±1.44 8.49±1.35 Height (SDS) - 3.47 - 3.17 - 3.75 - 4.07 - 3.1 -3.5±0.36 -2.7±1.5 Sitting height (SDS) - 2.1 - 2.0 - 2.25 - 4.2 - 2.0 -2.51±0.84 -2.57±0.93 Sitting 0.556 0.566 0.553 0.53 0.539 0.548±0.018 0.547±0.0
height/height ratio (1.5 SD) (2 SD) (0.8 SD) (0.2 SD) (1.8 SD) (1.26 ±0.66 SD) 1 (1.375 ±0.7 SD) Growth velocity
during last year (SDS) - 1.25 - 1.8 - 1.2 - 2.8 - 3.2 -2.05±0.81 -2.26±0.77 Weight (SDS) - 2.23 - 4.33 - 3.62 - 3.71 - 1.55 -3.08±1.03 -1.89±1.68 BMI (SDS) 0.11 - 2.64 - 1.07 - 1.34 0.33 -0.92±1.07 -0.88±1.19 Head circumference (SDS) - 1.5 - 2.0 - 1.2 1.5 - 0.66 -0.77±1.21 -0.66±1.33 Waist circumference (SDS) - 3.2 - 3.5 - 3.0 - 0.5 - 0.1 -2.06±1.45 -1.82±1.5
Bone age delay (years)
- 2.68 - 1.64 - 2.02 - 3.46 - 1.2 -2.2±0.79
-2.24±0.88
Five patients with suspect severe primary IGF-1 deficiency were Caucasian and declared Lithuanian origin of their family trees, from non-consanguineousparents. All patients were born full-term (at gestational weeks 38-40); therefore, standard values for the 40th gestational week (mean birth weight (BW) 3646 448 g and mean birth length (BL)51.7 1.95 cm for boys and mean BW 3506 424 g and mean BL 50.8 1.75 cm for girls) were used as reference. [30] The birth weights of patients ranged from -2.65 to +0.6 (-0.975 ± 0.62 SDS)
and birth lengths from -1.7 to +1.21 (-0.37 ± 0.57 SDS). None of the patients suffered from early postnatal events. Patient number 2 was the only one born small for gestational age (SGA); and all the others were born appropriate for gestational age (AGA). Although birth length and weight are a bit below the average but previous studies show that there is no correlation between birth length and weight and IGFD (9). Other researchers state an example in 2015, when they did a study and found that 9 children in their sample have confirmed IGFD and all 9 were born within the average weight (12). In our study 75% of the patients were born AGA but develop growth retardation later in life.
Parental heights were lower than mean of general population: fathers 171.3 3.8 cm (-1.28 0.62 SDS) and mothers 156.8 3.0 cm (-1.64 0.34 SDS).[31] The difference between target
(mid-parental) height and current height SDS was -1.842 0.945 (P=0.008 vs. 0). These results show the contribution of genetics and heredity on this disorder. We can clearly see the fact that all patients’ mothers and fathers are below average height. The retardation of sitting height were in keeping with retardation of height, though sitting height over height ratio was normal and near of the mean of general population 0.548±0.018 (1.26±0.66 SDS). [32] This measurement excludes the presence of any skeletal dysplasia and short lower limbs. The weight is decreased in all patients due to the fact that absence of IGF-1 will lead to decrease in muscle mass and bone growth that will result later in short stature persons with obesity and high adiposity; this fat deposits can overcome the decrease in weight that was caused by decrease in muscle mass and bone growth and thus will give us no good
information about the normal BMI of the person. He/she might have low BMI but a lot of fat. The mean head and waist circumference of the IGFD patients is lower than the average. Seventy five percent of our patients have below average head circumference and 100 % have below average waist circumference. This confirm the statement written by authors of a study done in 2012 which demonstrate the importance of IGF- 1 on head and waist circumference in addition to brain size which can lead to mental retardation as seen in 1 of our patients (patient number 2). These researchers gave IGF-1 treatment to IGF-1 deficient patients and stated that the result was a rapid increase in head circumference (17). Finally, there was a delay in bone age (mean is -2.2±0.79 years) similar to what other studies have postulated (10).
We cannot talk about delayed puberty in our case because all the patients are not in their puberty period. That’s why the importance of follow-up with these patients years later to check the puberty delay, bone growth velocity as they grow up, height and head and waist circumference after few years.
Some other medical notes are seen. Patient 2 suffer from a moderate mental retardation patient 3 from iron deficiency anaemia and patient 4 has a prominent forehead and 1 spot of café au lait.
Conclusion:
The main objectives of this study were to find out the prevalence of severe primary IGFD in Lithuania in the period between 2012-2015. We confirmed 4 patients out of 135 short stature patients to have IGFD, which correspond to 3%. In addition we collected auxological data, parental information and hormones level in the body to detect some clinical manifestations of this disease and compare them with other studies results. We also identified some GH
deficient patients and treated them with GH therapy and planning to follow them during treatment. GHD was seen in 37 patients which corresponds to 27% of all SS patients studied. In this research, we studied the effect of IGFD on auxological characteristics by measuring the height, sitting height, parent’s height, weight, BMI, head and waist circumference, bone age delay and velocity of bone growth) and on hormonal level such as prolactin, ALP, IGF-1 and GH. Add to this we tried to find a relation between IGFD and insulin resistance by calculating HOMA-IR and glucose and insulin level. Moreover, lipid profile was done to find a correlation between absence of IGF-1 and body fat. Prenatal information such as gestational age, weight and length at birth was collected trying to find if they have any effect on IGFD development.
These measurements and tests are done on patients suspected for IGFD after collecting all the data necessary according to the diagnostic criteria stated before and excluding all secondary factors that can influence our study results such as puberty, medicines, and some other diseases.
In auxological part, no correlation was found between birth data (birth weight, birth length, gestation age) and IGFD development. We have seen 3 out of the 4 IGFD patients born AGA but all of them had lower than the average birth weight and length. The contribution of genetics and hereditary factors are seen clearly as all the patients both parents have lower than average height which prove that a genetic cause is related to the disease. Another fact we concluded from our results was that as the patient grows up in age, the growth velocity decreases. Lastly, IGFD is obviously decreasing head and waist circumference of the patients and promoting a delay in bone age relatively to chronological age. This statement is
confirmed by other studies as well (17).
In hormonal part, it is not uncommon to see that GH levels are normal, IGF-1 levels are below -3SD of the average, which are part of the criteria diagnosing IGFD, and that the difference of IGF-1 after its generation test is less than 50% in all patients confirmed with disease. Prolactin and ALP levels shows no correlation with the disease as they are both
normal in all the patients. We couldn’t find any relation between insulin resistance and IGFD; HOMA-IR in all patients is normal and none of these have high level of glucose or diabetes. Similarly, no hypercholesterolemia was detected in any of the patients; but, a higher than normal LDL and lower than normal HDL levels were detected, and confirmed
dyslipidemia might lead to cardiovascular risk later in life. The 2 reasons we have thought about that might led to absence of these 2 metabolic characteristics might be physical activity of the child which can decrease body fat and the small age that led us to formulate a
hypothesis that more time is needed for body fat deposition.
Follow up is indispensable and will lead us to confirm many statements formulated by other researchers or create new ones that might also contradict with previous studies. Does really insulin resistance and body fat develop later in the life of these patients? Will they have a delayed puberty or no puberty at all? What will happen to their head and waist
circumference? Can it be treated so that height and sitting height get back to normal? All of these questions need time and work to give us answers that are very helpful in our
understanding of the topic of IGFD.
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