Serum parathyroid hormone levels and serum calcium levels from birth to senescence.

1. Calcium and immunoreactive parathyroid hormone (iPTH) levels were measured in sera of 1334 normal subjects ranging from newborn to over 80 years of age. Albumin was measured in samples from the population of adults, which was 80% white, 15% black and 5% oriental. 2. Serum calcium and iPTH levels in children tended to be higher in the first three years of age; no sex differences were noted. Values for serum calcium and iPTH were higher in children than in adults. 3. Serum calcium, iPTH and albumin showed more variation in groups of white, black and oriental women than in similar groups of men. In white females the mean serum calcium remained fairly constant until age 60, whereas in black women it rose steadily from age 20-29 until age 50-59. Serum iPTH levels were lower in black women than in white women and usually were not measurable in oriental women. 4. In men (white, black and oriental) there was a steady decrease in mean serum calcium with age, and iPTH levels were not different from those observed in white women. 5. Although the number of samples from oriental women was small, the serum calcium was consistently lower and serum albumin was constantly higher than in white or black women, and iPTH levels usually were unmeasurable.