Calcium, phosphate and albumin in serum. A population study with special reference to renal stone formers and the prevalence of hyperparathyroidism in middle-aged men.

Serum valuse for calcium, phosphate and albumin have been determined in a population study of 2322 49-50-year-old men participating in a health examination survey. Calcium and albumin were significantly correlated (r = 0.34) but adjustment for albumin only caused minor effects on the distribution of calcium. No inverse relationship was found between calcium and phosphate. Seasonal variations over the three years of the health survey could not be established for either calcium or phosphate, whereas there was a slight tendency for albumin to decline during summer. The prevalence of hyperparathyroidism (HPT) in this population of men up to the age of 50 was 0.3% and among those with recurrent renal stones 5.3%. All subjects with verified HPT had a history of recurrent renal stones. One man on thiazide treatment had a slight elevation of calcium which returned to normal after cessation of the drug. No other case of hypercalcemia besides those caused by HPT was found. Mean values and frequency distributions for calcium, phosphate and albumin were almost identical in renal stone formers and matched controls. Hence it seems likely that other factors than those which markedly affect serum levels of calcium and phosphate are of major importance in common renal stone formation.