Salivary Testosterone Concentration and Testicular Volume in Male Infants

Abstract

In order to investigate the changes in testicular volumes (TV) and salivary testosterone concentrations (ST) in normal male infants aged from birth to one year, TV in 158 and ST in 61 infants were measured cross-sectionally during this period. ST of normal male adolescents in Tanner's pubic hair stage from P2 to P5 (n = 20) were also measured as the control. To clarify the relationship between remarkable height increase and testosterone (T) during early male infancy, longitudinal follow-up of 10 male infants (4 from birth to 4 months, 6 from birth to 7 months) were also carried out by simultaneous measurement of ST and crown-heel length. Maximum TV (ml) was observed at 1–4 months (1.7 ± 0.6) (mean±SD) and was significantly higher than the values at birth (0.5 ± 0.1, P<0.01) and at 6–12 months of age (1.4±0.4, P<0.01). Maximum ST (ng/dl) was also observed at 1–4 months, with the mean value being 3.4±1.5, which was significantly higher than 1.9±0.8 at 6–12 months (P<0.01). The ST at four month was not significantly different from that at Tanner's pubic hair stage P2. The longitudinal study showed that the rise in ST was concomitant with the maximum increase in crown-heel length at 1–4 months. The fluctuations in ST and height increase were also apparently synchronous during the first year. © 1985, The Japan Endocrine Society. All rights reserved.