Male Hypogonadism

Male delayed puberty

Segal (2009) assessed the performance of the GnRH test and HCG test for distinguishing constitutional delay of growth and puberty (CDGP) from hypogonadotrophic hypogonadism (HH).

In the GnRH test, 2.5 µg/kg GnRH was given as an IV bolus, and FSH/LH measured at 0,20 and 60 minutes. Levels at 20 min were higher than at 60 min, so only the 20 min values were used.

Parameter HH CDGP Optimum cut-off Performance
Serum FSH (U/litre)
Unstimulated 0.9 (0.8) 2.2 (1.3)
Peak (20 min) 2.2 (1.5) 5.1 (3.3) 3.7 Sens 90%, spec 52%, PPV 41%
Serum LH (U/litre)
Unstimulated 0.7 (0.7) 0.9 (0.9)
Peak (20 min) 1.7 (1.7) 8.9 (6.6) 2.8 Sens 90%, spec 84%, PPV 69%

Note that improved discriminatory performance was obtained by combining the GnRH test with both 3-day and 19-day HCG tests.

Adult hypogonadism

Circadian rhythm in testosterone, from Clin Endo 2008 69 515

Morning testosterone measurement is important. 'Low' testosterone can be normal, even in healthy young men, in the afternoon. A 'normal' afternoon testosterone makes true hypogonadism unlikely.

Calculated free testosterone - click here. Free androgen index is for women.