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Salivary testosterone concentration and testicular volume in male infants
Insights
Testicular volume and salivary testosterone concentrations peak in male infants between 1-4 months. This early rise in testosterone correlates with significant height increases during infancy.
Area of Science:
- Pediatric Endocrinology
- Andrology
- Human Growth and Development
Background:
- Testosterone plays a crucial role in male development.
- Understanding testosterone dynamics in infancy is vital for assessing normal growth.
- Limited data exists on early infant testosterone levels and testicular growth.
Purpose of the Study:
- To investigate changes in testicular volume (TV) and salivary testosterone concentrations (ST) in male infants from birth to one year.
- To explore the relationship between height increase and testosterone levels during early male infancy.
Main Methods:
- Cross-sectional measurements of TV (n=158) and ST (n=61) in infants aged 0-12 months.
- Longitudinal follow-up of 10 male infants measuring ST and crown-heel length.
- Comparison of infant ST with adolescent controls (Tanner stages P2-P5, n=20).
Main Results:
- Maximum TV observed at 1-4 months (1.7 ml), significantly higher than at birth and 6-12 months.
- Peak ST levels occurred at 1-4 months (3.4 ng/dl), significantly higher than at 6-12 months (1.9 ng/dl).
- Longitudinal data showed ST rise was concomitant with maximum crown-heel length increase at 1-4 months.
Conclusions:
- Male infants exhibit peak testicular volume and salivary testosterone concentrations between 1-4 months of age.
- Testosterone levels in 4-month-old infants are comparable to early adolescent stages (Tanner P2).
- Early infant height spurt is closely associated with concurrent increases in salivary testosterone levels.
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 public 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 less than 0.01) and at 6-12 months of age (1.4 +/- 0.4, P less than 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 less than 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.