Testosterone

LH

FSH

Etiology

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↑

↑

Primary testicular disorder (hypergonadotropic hypogonadism) 

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¯

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Hypogonadotropic hypogonadism (secondary to pituitary or hypothalamic disorder)

N

N

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Seminiferous tubular failure / Sertoli-cell-only syndrome / Status after hemicastration

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↑

N

Androgen resistance syndrome / Hyperthyroidism

N

N

N

Disorders of sperm transport (ductal or epididymal obstruction) / Spermatogenic arrest