Adjustment of serum total calcium for albumin concentration: values change with age in women but not in men.

A total of 669 women and 609 men were selected from a laboratory computer data base in such a way that they would be expected to have a low prevalence of disturbances of calcium homeostasis but a wide range of serum albumin concentrations. The least squares regression coefficients of total calcium on albumin did not differ between men and women, nor did they differ at different ages. Mean serum albumin-adjusted calcium concentrations did not change with age in men from 1 to 90 years, and values were similar in women aged 1-20 years. However, adjusted calcium concentrations were significantly lower in women aged 21-50 and higher in women aged 61-90 than in younger women and all men. The differences were small and are unlikely to affect clinical interpretation.