[Serum levels of the tartrate-resistant isoenzyme, acid phosphatase, for the evaluation of bone remodeling in hyperthyroidism].

Tartrate-resistant acid phosphatase (TRAP) is one of the acid phosphatase isoenzymes. It is secreted by osteoclasts so it has been proposed as a marker of bone resorption. Bone turnover is high in hyperthyroidism due to an increase in both bone resorption and formation. The aim of the study was to measure serum TRAP as well as other markers of bone metabolism in 20 fertile age females affected by Graves-disease; 11 patients were also studied after euthyroid state was attained by means of a 6 month course of methimazole treatment. TRAP was measured with the colorimetric method using p-nitrophenylphosphate as substrate. Free thyroid hormones, TSH, serum calcium (corrected for albumin concentration), phosphate, osteocalcin, alkaline phosphatase, parathormone intact molecule, and urinary excretions of calcium, phosphate and hydroxyproline were measured, too. Twenty-eight healthy fertile women made up the control group. Untreated patients had a significant increase of TRAP, osteocalcin, serum calcium, alkaline phosphatase and urinary excretion of calcium and hydroxyproline. A significant fall in all these parameters but alkaline phosphatase was disclosed comparing patients before and after treatment, nevertheless only urinary calcium became not significantly different from the controls. TRAP showed a significant correlation with free T3 levels but not with hydroxyproline excretions. This survey on fertile age women with Graves' disease shows a significant increase in serum concentration of TRAP, which decreases, but doesn't get normalization, when euthyroidism is attained by a six month course of methimazole therapy.(ABSTRACT TRUNCATED AT 250 WORDS)