What is anti‑Müllerian hormone (AMH) in males, what are the age‑specific reference ranges, and in which clinical situations is measuring it indicated?

Anti-Müllerian Hormone (AMH) in Males

What AMH Is and Its Physiological Role

AMH is a glycoprotein hormone secreted exclusively by Sertoli cells in the testes that causes regression of Müllerian ducts during male fetal development and serves as the single most reliable biochemical marker of functional testicular tissue from birth through early puberty. 1, 2

• AMH production begins at testicular differentiation around 8 weeks of gestation and is detectable in male fetal serum from 19 weeks onward, with concentrations averaging 40.5 ng/mL between 19-30 weeks and 28.4 ng/mL from 30 weeks to term 2
• In the first trimester, AMH expression occurs independently of gonadotropins, but from the second trimester forward, FSH and estrogens stimulate AMH production 1, 3
• At puberty, intratesticular testosterone and the presence of meiotic germ cells dramatically suppress AMH expression, causing serum levels to decline to residual values that persist throughout adult male life 4, 3

Age-Specific Reference Ranges

Serum AMH levels in males vary dramatically by developmental stage, with peak concentrations during infancy and childhood (approximately 43.1 ng/mL in boys aged 2 months to 2 years), followed by a sharp decline at puberty to near-undetectable adult levels. 2, 4

Key developmental patterns:

• Fetal period (19-30 weeks): 40.5 ± 3.9 ng/mL 2
• Late fetal/perinatal: 28.4 ± 6.1 ng/mL (lower than postnatal, suggesting sluggish production perinatally) 2
• Infancy to prepuberty (2 months-2 years): 43.1 ± 3.7 ng/mL 2
• Pubertal decline: Progressive decrease as testosterone rises and spermatogenesis begins 3
• Adult males: Residual, near-undetectable levels 4

Important caveat: AMH assays lack international standardization, so interpret results using laboratory-specific reference ranges 5

Clinical Indications for Measuring AMH in Males

1. Cryptorchidism and Nonpalpable Gonads (Primary Indication)

In boys with nonpalpable gonads, serum AMH is the most useful single marker to distinguish between intra-abdominal testes and anorchism, eliminating the need for hCG stimulation testing. 1, 6

• Detectable AMH confirms the presence of functional testicular tissue 1, 6
• Undetectable AMH in bilateral nonpalpable gonads indicates anorchism 6
• AMH levels are lower in bilateral cryptorchidism compared to unilateral cases, reflecting reduced Sertoli cell mass 1
• Post-orchiopexy monitoring: AMH increases after surgical relocation of testes to the scrotum, indicating that ectopic positioning causes at least partially reversible testicular dysfunction 1

2. Cryptorchidism with Micropenis: Distinguishing Central vs. Primary Hypogonadism

Low AMH combined with low FSH in a boy with cryptorchidism and micropenis indicates central (hypothalamic-pituitary) hypogonadism, and AMH serves as an excellent marker of effective FSH replacement therapy. 1, 6

• In congenital central hypogonadism, AMH is low in infancy but increases with FSH treatment 6
• This pattern distinguishes central hypogonadism from primary testicular failure 6

3. Disorders of Sex Development (DSD)

AMH determination is a first-line test in DSD evaluation: low AMH indicates gonadal dysgenesis, whereas normal or elevated AMH suggests isolated defects in androgen synthesis or androgen insensitivity. 1, 6

• Low/undetectable AMH: Points to dysgenetic DSD (e.g., gonadal dysgenesis, ovotesticular DSD) 6
• Normal/high AMH: Indicates intact Sertoli cell function with defects in androgen production (e.g., 17β-hydroxysteroid dehydrogenase deficiency, 5α-reductase deficiency) or androgen action (e.g., androgen insensitivity syndrome) 1, 6
• In 46,XX males with SRY translocation, AMH levels are in the normal male range, confirming functional testicular tissue 2

4. Persistent Müllerian Duct Syndrome (PMDS)

In boys with cryptorchidism and a uterus/Fallopian tubes on imaging, AMH measurement directs genetic testing: undetectable AMH indicates AMH gene mutations, while normal/high AMH points to AMH receptor gene defects. 6

5. Syndromic Disorders Affecting Testicular Function

AMH assessment reveals distinct patterns of Sertoli cell dysfunction across genetic syndromes:

• Klinefelter syndrome (47,XXY): AMH remains normal until mid-puberty, then declines, indicating preserved Sertoli cell function in childhood 1, 6
• Down syndrome: AMH is low from early postnatal life, reflecting primary testicular dysfunction 6
• Noonan syndrome and Prader-Willi syndrome: AMH is reduced, indicating impaired Sertoli cell function 1

6. Precocious Puberty

Low serum AMH occurs in both central (gonadotropin-dependent) and gonadotropin-independent precocious puberty due to premature androgen suppression of AMH; levels normalize 3-6 months after treatment. 3

• The decline in AMH reflects early androgen-mediated suppression rather than gonadotropin action 3
• AMH recovery after treatment confirms effective suppression of precocious development 3

Common Pitfalls and Caveats

• Do not use AMH to diagnose PCOS in males—all the provided PCOS literature 7, 8, 5 addresses AMH in females and is irrelevant to male physiology
• Timing matters: AMH is most informative from birth through early puberty; adult male levels are too low to be clinically useful 4
• Assay variability: Results must be interpreted using the specific laboratory's reference ranges due to lack of standardization 5
• Perinatal dip: AMH is lower in late fetal life and the immediate postnatal period compared to later infancy, which may reflect transient suppression 2
• Indirect androgen regulation: Androgens suppress AMH indirectly (no androgen response elements exist on the AMH promoter), explaining the slow response to androgen withdrawal 3