The relationship between ultrasonographically measured testicular volumes and cord blood inhibin B concentrations in healthy term male neonates

Serum inhibin B (INHB) concentrations are associated with testicular volumes (TV) in all periods of childhood. The aim of the study was to investigate the relationship between TV measured by ultrasonography (US) and cord blood inhibin B and total testosterone (TT) concentrations, stratified by mode of delivery. In total 90 male infants were included. Testes of healthy, term newborns were evaluated by US on the third day after delivery. TV were calculated using two formulae: The ellipsoid formula [length (mm) × width (mm²) × π/6] and Lambert formula [length (mm) x width (mm) x height (mm) x 0.71]. Cord blood was taken for the determination of total testosterone (TT) and INHB. TT and INHB concentrations were evaluated according to TV percentiles (<10th, 10th-90th, >90th). There was a strong positive correlation between mean TV calculated with both formulae by percentile group (r = 0.777, r = 0.804, r = 0.846; p < 0.001). Cord blood INHB, but not TT were significantly lower in newborns with TV < 10th percentile compared to those with TV between 10 and 90th percentile and > 90th percentile (p < 0.05). There was a positive correlation between left and right TV calculated by either formula, and cord blood INHB (r = 0.212, 0.313, 0.320, 0.246,p < 0.05), not TT. There was no significant difference between hormones and TV when grouped by mode of delivery (p > 0.05). The Lambert and ellipsoid formulas are equally reliable in calculating neonatal testicular by ultrasound. INHB concentration is high in cord blood and positively correlated with neonatal TV. Cord blood INHB concentration may be an indicator for early detection of testicular structure and function disorders in neonates.