PP
CALCIUM TO PHOSPHORUS CA P RATIO AS AN ACCURATE INDEX FOR THE
DIAGNOSIS OF PRIMARY HYPERPARATHYROIDISM PHPT AND HYPOPARATHYROIDISM
HYPOPT
S De Vi ce i A Re aci P A ie i E Ka a P A ad i A Ba e ie i V R chi a B Made U i à di E d c i gia Di a i e di Scie e Bi ediche Me ab iche e Ne cie e U i e i à di M de a e Reggi E i ia U i à di E d c i gia Di a i e di S ecia i à Mediche A ie da O eda ie U i e i a ia di M de a M de a U O C E d c i gia P ic i ic di S O a Ma ighi DIMEC A a Ma e S di B g a B g a U i à di E d c i gia e Me ab i O eda e U i e i a i S Ma ia de a Mi e ic dia di Udi e Udi e U i à di E d c i gia A ie da P i cia e Se i i Sa i a i T e T e UOSD di E d c i gia e Diabe gia O eda e M B fa i i di Ce e a AUSL de a R ag a Ce e a
BACKGROUND The diagnosis of PHPT and chronic HypoPT is still challenging, mainly due to the wide spectrum of clinical and biochemical presentation and the lack of validated diagnostic index in literature. The serum Ca/P ratio has been proposed as an accurate tool to diagnose PHPT in a small sample of patients, while no data is available about its possible application for HypoPT.
AIM To validate the serum Ca/P ratio as a diagnostic index for PHPT and to investigate its diagnostic performance in the diagnosis of HypoPT by analyzing a large series of data coming from a multicenter study.
METHODS Multicenter, retrospective, case-control study, including PHPT patients and HypoPT
patients, compared with controls. Main outcomes: serum Ca, P, albumin, creatinine, parathyroid
hormone (PTH) and -OH vitamin D (only for controls and PHPT). S a i ica a a i Comparisons
among groups were performed by the nonparametric Kruskal-Wallis, followed by the Dunn’s post hoc test. The diagnostic accuracy of Ca/P ratio was investigated by receiver operator characteristics (ROC) curves in order to define cut-off points (with the highest sensitivity and specificity).
RESULTS The Ca/P ratio was significantly different among groups, resulting higher in PHPT and lower in
HypoPT patients than controls (p . ). At ROC curve analysis, the Ca/P ratio above . was defined
for the diagnosis of PHPT (sensitivity . , specificity . ), while the Ca/P ratio below . for the
diagnosis of HypoPT (sensitivity . , specificity . ). Considering the PHPT group, the cut-off of .
for Ca/P was able to specifically identify patients with normocalcemic PHPT (sensitivity . ,
specificity . ).
CONCLUSIONS This study further validates the serum Ca/P ratio as a highly accurate diagnostic index for PHPT, defined by Ca/P above . . For the first time, a Ca/P ratio below . is proposed to identify HypoPT patients. Our findings confirm the reliability of this index to screen and/or rule out disorders of Ca-P metabolism.
