How to Answer? Way Question May be Asked? Concept Endocrine—Hyperparathyroidism

Endocrine—Hyperparathyroidism

Concept

One of many possible causes of hypercalcemia. Must rule out common causes of hypercalcemia first, then remember primary, secondary, and tertiary types of hyperparathy- roidism.

(1) Primary hyperparathyroidism, about 80% ade- noma; about 2% double adenoma

(2) Secondary hyperparathyroidism from hyperplasia often secondary to renal failure

(3) Tertiary hyperparathyroidism from autonomous functioning glands after etiology causing secondary hyperparathyroidism has been treated (most com- mon in renal transplant patients)

Way Question May be Asked?

“61 y/o female with an elevated calcium level on routine blood tests with her only complaint of fatigue. What do you want to do?” Sometimes you will be given more information like renal stones, or abdominal pain, consti- pation, arthralgia, myalgia, depression, ulcers, pancreati- tis, osteitis fibrosa cystica, but rarely all of the symptoms associated with elevated calcium (renal stones, bone pain, constipation, fatigue, ulcer, depression, emotional lability).

How to Answer?

First, need to be able to rule out common causes of hyper- calcemia. Many mnemonics here, but all include: malig- nancy (breast, lung, prostate, multiple myeloma), primary and secondary hyperparathyroidism, sarcoidosis, thi- azides, immobilization, familial hypocalciuric hypercal- cemia, milk-alkali syndrome, and hyperthyroidism.

Second, to document hyperparathyroidism, need to con- firm hypercalcemia on repeat blood tests, then:

(1) Check Cl/PO

level (greater than 30 suggestive of 1˚

HP)

(2) Get PTH level

(3) Low PO

(high in renal failure)

(4) +/− x-ray of hands to look for cystic/resorptive changes

(5) 24 h urinary calcium for rare hypercalcemic hypocal- ciuria

Third, localization studies:

(1) CT scan or MRI of neck to mediastinum (2) Thallium-technetium scan

(3) Ultrasound (4) Sestamibi scan

(5) Invasive studies like arteriography and selective venous sampling for recurrences

(6) Many believe best localization study is experienced parathyroid surgeon (but don’t go there on Oral Exam unless you are one!)

Indications for surgery are two-fold: symptomatic hypercalcemia, or

calcium > 11 with signs of bone disease

Procedure

(1) If single adenoma, excise the adenoma, be careful not to rupture capsule, and biopsy 1–2 other glands to confirm they are normal

(2) If hyperplasia, total parathyroidectomy with auto- transplantation in to forearm

(3) If parathyroid Ca (very high pre-op Ca levels), en bloc resection with thyroid lobe on that side and regional lymph nodes

(4) Gold standard is to explore all 4 glands (most tradi- tional answer)

(a) If not going to do this, may mention intraoper- ative PTH level

(b) Even 4 normal glands are found, continue neck exploration for rare presence of 5 or 6 glands

52

Part 1.qxd 10/19/05 2:51 AM Page 52

Strikeouts 53

(5) Consider cryopreservation in borderline cases espe- cially if find only 3 hyperplastic glands

(a) You missed a gland—normal or abnormal (b) Patient has only 3 glands

If you cannot find a gland:

(1) If upper gland, check paraesophageal, retrolaryn- geal spaces, posterior mediastinum, and do thyroid lobectomy on that side

(2) If lower gland, check tracheoesophageal groove, carotid sheath, thymus, thyroid, anterior medi- astinum

(3) If you still can’t find gland, don’t do sternotomy first time around, but follow post-op Ca/PTH levels

Common Curveballs

Post-op has persistently elevated calcium/or comes back six months later with elevated calcium → be method- ical with complete work-up including calcium, phos- phorus, and PTH levels; MRI, sestamibi, U/S; one of four choices:

(1) Missed adenoma (most likely)—could be a 5th gland, in mediastinum, or on same side

(2) Missed hyperplasia (3) Parathyroid carcinoma (4) Parathyromosis Can’t find 4 glands

There will be more than 4 glands

Asked when you would consider cryopreservation of any of the glands

Part of a MEN syndrome Post-op hypocalcemia Post-op airway compromise Post-op hoarseness

Pt sent to you after previously failed neck exploration elsewhere

Asked to comment on why four-gland exploration bet- ter than exploration on just one side (justify what- ever position you offer)

Pt may originally present very subtly with only fatigue or renal stones

Will be asked an innocent question like “How does PTH work?”( →increase bone resorption, increases renal resorption of Ca and renal secretion of phos, and stimulates Vit D formation)

Management of hypercalcemic crisis (treat with IVF, lasix, steroids, calcitonin)

Parathyroid carcinoma

Strikeouts

Failing to rule out MEN syndrome

Failing to rule out common causes of hypercalcemia Performing median sternotomy first time operation

when find only 3 glands

Finding a single adenoma and stopping operation Going into long discussion about radioguided surgery

for minimally invasive parathyroidectomy (very dan- gerous on the exam to describe any cutting edge sur- geries/technologies)

Not knowing how to deal with post-op persistent hypercalcemia

Not knowing how PTH works Not knowing indications for surgery

Not knowing percentage for finding single adenoma (80%)

Not knowing how to deal with post-op complications Not knowing where to look for “missing” upper or

lower gland

Part 1.qxd 10/19/05 2:51 AM Page 53