Metabolic bone disease in the elderly. Biochemical studies in three different racial groups living in South Africa.

In an attempt to detect biochemical evidence of metabolic bone disease in the aged, we measured plasma parathyroid hormone (PTH) concentrations, in addition to plasma calcium, phosphorus, alkaline phosphatase and creatinine levels, in elderly White, Black and Indian women. All three ethnic groups demonstrated raised mean PTH concentrations. The Black patients, however, showed the greatest mean PTH elevation and the lowest plasma calcium level. Increased PTH secretion in elderly females may reflect either an age-related decline in renal function or subclinical osteomalacia. Elderly Black women seem particularly susceptible to the latter disorder, probably because of dietary and environmental factors.