Plasma 25-Hydroxyvitamin D and Alkaline Phosphatase Isoenzymes in Hyperthyroidism

Abstract

SUMMARY Plasma 25-hydroxyvitamin D (25-0HD) values in 22 hyperthyroid patients did not differ significantly from those of controls matched for age, sex, and the time of year that plasma samples were taken. In the hyperthyroid group, plasma alkaline phosphatase was significantly higher than in controls, and an increase in bone type alkaline phosphatase occurred in 50 %. In the 18 female hyperthyroid patients the plasma y-glutamyl transferase was significantly increased compared with controls. Mean values for plasma albumin, alanine transferase, and calcium showed no significant difference between hyperthyroid and control patients.Results on the basis of clinical diagnosis supported by an FTI of over 140 (the upper limit of normal for this laboratory). Control patients were those in whom the FTI had been requested by a clinician and were normal. Control patients were matched with hyperthyroid patients for age (± 3 years), sex, and time of year that blood samples were taken (within one month). Patients were excluded from this study if they had received antithyroid therapy before having the blood sample taken or if there was insufficient plasma for all of the analyses to be done. Blood samples were taken over the period July to October 1977.Plasma 25-0HD was measured by a competitive protein binding method (Haddad and Chyu, 1971), modified by the use of diluted human serum as the source of binding protein. Plasma AP isoenzymes were separated by electrophoresis (Cleeve, 1978).Plasma AP, ALT, GGT, FTI, albumin, and calcium were measured by the methods in current use in this laboratory. Calcium values were corrected for the level of plasma albumin (Tomlinson and O'Riordan, 1978). Normal ranges are shown in the Table. There were 18 women and four men in each group, their ages ranging from 19 to 77 years.There were no significant differences in mean plasma 25-0HD, ALT, albumin, and calcium concentrations between the hyperthyroid patients and controls. Two patients in each group had consecutively 25-0HD values below our lower limit of normal. 320Material and methods Hyperthyroid patients were selectedPlasma 25-hydroxyvitamin D (25-0HD) has been reported (Valentzas et al., 1977) to be markedly reduced in hyperthyroidism, and it was, therefore, suggested that it might be an important clue to our understanding of hyperthyroid bone disease. Other workers (Mosekilde et al., 1977) found that the free thyroxine index (FT!) correlated with the serum 25-0HD, but that the differences between the 25-0HD values in hyperthyroid patients and in controls was not nearly as great. These latter workers found a lack of correlation between serum 25-0HD and bone histomorphometry in hyperthyroidism and concluded that the lowered 25-0HD was of minor importance in the development of hyperthyroid bone disease.Hypercalcaemia occurs in at least 8 % of hyperthyroid patients (Baxter and Bondy, 1966), and in one series 51 % (Mosekilde et al., 1977), the serum calcium being positively correlated with the degree of hyperthyroidism and inversely correlat...

Vitamin D Metabolism in Hyperthyroidism

“…We found no difference in serum 25 OH D3 concentrations in the patients before treatment compared with the controls and there was no significant change after carbimazole therapy. Other studies have also shown similar serum 25 OH D3 concentrations in hyperthyroid patients and control subjects matched for the time of the year that samples were taken (Cleeve & Brown, 1978;Bouillon et al, 1980). Serum 24,25(OH)2D3 concentrations were increased in our patients before therapy, though not significantly.…”

The Hydroxylation of Vitamin D on C25 in Thyrotoxicosis The Role of the Activity of Microsomal Liver Enzymes

“…Immediately other investigators conducted estimations of 25OHD 3 plasma levels in thyrotoxicosis. Some of them confirmed our findings but others found normal or slightly increased values [4][5][6][7][8][9]. To explain the variety of 25OHD 3 plasma levels in hy-perthyroidism we moved as follow.…”

“…Hyperparathyroidism has been found to coexist with thyrotoxicosis in a frequency greater with that of normal population. Parathyroid hormone blood levels have been reported as increased, normal or decreased [26,33], while the mean of alkaline phosphatase levels are significantly raised [4,5,30]. Description of macroscope bone changes are rare, since diagnosis and treatment early are offered for thyrotoxicosis.…”

Propranolol and the hypercalcaemia of thyrotoxicosis

“…Reduced 25-OH vitamin D levels have been attributed (Hunstein et al 1977) to an increased metaboism of vitamin D in thyrotoxi¬ cosis. This finding has not however been confir¬ med by all groups (Cleeve & Brown 1978) and in addition the effect of hyperthyroidism on other potent metabolites of vitamin D has not to date been studied. However the reduced intestinal absorption of calcium (Haldimann et al 1980), decreased urinary excretion of phosphorus and increased excretion of calcium (Hendriks 8c Smeenk 1979) is strong presumptive evidence that vitamin D and parathyroid function are suppressed in hyperthyroidism, suggesting that the primary abnormality may be the increased bone résorption.…”