Factors Influencing Retention of Nitrogen and Calcium in Period of Growth

Puberty in the girl was shown in a previous communication¹to be associated with a fall in the retention of calcium and nitrogen, a fact which might be anticipated if one recalls the prompt diminution in the rate of growth associated with the attainment of sexual maturity. The phenomena of a rapid increase in the rate of growth preceding puberty and the fall following it have been shown to correlate with physiologic and not with chronologic age. It has likewise been shown that there is a rise in the basal metabolic rate associated with the increasing rate of growth and the increasing retention of calcium and nitrogen and a fall in the metabolic rate coincident with the diminishing retention of these two substances; in other words, changes in the metabolic rate paralleled directly, rather than inversely, the retentions of calcium and nitrogen, though an inverse relation might have been