[Biochemical profile of primary hyperparathyroidism. Comparative study with hypercalciuric renal lithiasis]

Primary hyperparathyroidism (PH) is now considered a common condition. Its frequency and the deleterious long-term effects of hypercalcemia make a correct diagnosis mandatory. We attempted to evaluate the usefulness of the indexes of parathyroid function and hormone measurements more commonly used in the diagnosis of PH. To this end we studied 64 patients, distributed in three groups: group with PH, group with hypercalciuric renal lithiasis (HRL) and control group (CG). The results were evaluated with a test of comparison of means and a stepwise discriminating regression analysis. The 8 most useful measurements to differentiate PH from HRL and CG were serum calcium, corrected serum calcium, serum phosphorus, fasting calcium excretion (FCE), maximal tubular calcium reabsorption (MTCR), maximal tubular phosphate reabsorption (MTPR), osteocalcin, PTH half molecule (PTH-HM) and 1,25-dihydroxyvitamin D. The 3-variable and 4-variable groups with a highest discriminating ability were: serum calcium, FCE and PTH-HM, and serum calcium, FCE, PTH-HM and MTPR. We think that the measurement of these four variables is the most adequate strategy for the diagnosis of PH.