Contribution of the adrenal gland to the production of androstenedione and testosterone during the first two years of life

Androstenedione and testosterone were measured in whole adrenal
glands of 56 previously healthy boys who died suddenly between
birth and 2 yr of age. In each adrenal gland, the concentration of
androstenedione considerably exceeded that of testosterone. The
highest concentrations were found during the first week of life
(median, 295 ng/g; range, 98- 320 ng/g). Thereafter, values
decreased rapidly until the end of the first year of life (median,
10 ng/g; range, 4.4-22.7 ng/g). Adrenal testosterone concentrations
averaged 15% of those of androstenedione in the same gland and
similarly decreased until the end of the first year. The decrease
of adrenal androgen concentrations paralleled the involution of the
fetal adrenal zone. A close correlation existed between the
concentration of androstenedione in adrenal tissue and plasma.
However, no correlation existed between adrenal and plasma
testosterone. When the adrenals and testes of the same infant were
compared, there was 10 times more androstenedione in the adrenals
than in the testes during the first 2 yr of life. The testes
contained more testosterone than the adrenals only during the first
4 months. Thus, in infant boys the adrenals are the main source of
androstenedione during the first 2 yr. After the sixth month of
life, they also are the main source of testosterone.