Table 1:

Fetal-onset male hypogonadism.

		Genitalia	Childhood					Puberty-Adulthood
			LH	FSH	T	AMH	Inh B	LH	FSH	T	AMH	Inh B	Sperm.
Primary hypogonadism (Testicular)	Generalized gonadal failure
	Gonadal dysgenesis	Female or ambiguous	N-H	N-H	L-ND	L-ND	L-ND	H	H	L-ND	L-ND	L-ND	Azoosp.
	Testicular regression syndrome Testicular torsion	Micropenis Empty scrotum	N-H	N-H	L-ND	L-ND	L-ND	H	H	L-ND	L-ND	L-ND	Azoosp.
	Klinefelter syndrome, XX Male	Male	N	N	N	N	N	H	H	N-L	L-ND	L-ND	Azoosp.
	Dissociated gonadal failure
	Leydig cells
	Hypoplasia/aplasia Steroidogenic defects	Female or hypovirilized	N-H	N	L-ND	N-H	N	H	H	L-ND	N-H	L-ND	Azoosp.
	INSL3 mutations	Cryptorchidism	N	N	N	N	N	N	N-H	N		N-L	Oligosp.
	Sertoli cells
	FSH-R mutations	Small testicles	N	N	N	L	L	N	H	N	L	L	Oligosp.
	AMH mutations	PMDS	N	N	N	ND	N	N	N	N	ND	N	N
Secondary hypogonadism (Central)	Generalized gonadal failure
	Multiple pituitary hormone deficiency	Micropenis, cryptorchidism	L	L	L	L	L	L	L	L	L	L	Oligosp./azoosp.
	Isolated central hypogonadism	Micropenis, cryptorchidism	L	L	L	L	L	L	L	L	L	L	Oligosp./azoosp.
	Dissociated gonadal failure
	Multiple pituitary hormone deficiency	Small testicles	N	L	N	L	L	N	L	N		L
	Isolated central hypogonadism: TAC3 or TACR3 mutations	Micropenis, cryptorchidism	L	N	L	N	N	L	N	L		L	Oligosp./azoosp.
	LHβ mutations	Micropenis, cryptorchidism	L	N	L	N	N	L	H	L	H		Oligosp./azoosp.
	FSHβ mutations	Small testicles	N	L	N			H	L	N			Oligosp./azoosp.
Dual hypogonadism (Combined)	Generalized gonadal failure
	Prader-Willi syndrome X-linked congenital adrenal hypoplasia	Micropenis, cryptorchidism	L-N	L-N	L-N	L	L	N	N	L	L	L	Oligosp./azoosp.

L, N, H: Low, Normal, High with respect to reference range for age in males ND: non-detectable. Male hypogonadism: an extended classification based on a developmental, endocrine physiology-based approach. Andrology. 2013;1(1):3–16. © 2012 American Society of Andrology and European Academy of Andrology.