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FSH and LH in Men: A Complete Guide





Overview of FSH and LH

FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone) are gonadotropins produced by the anterior pituitary gland under the regulation of the hypothalamic hormone GnRH (gonadotropin-releasing hormone).

  • FSH in Men: Stimulates Sertoli cells in the testes to support sperm maturation.
  • LH in Men: Stimulates Leydig cells in the testes to produce testosterone.



Microbiology & Physiology

  • Origin: Both FSH and LH are glycoprotein hormones secreted by the anterior pituitary.
  • Regulation: Controlled by GnRH pulses from the hypothalamus and feedback from sex steroids (testosterone, estradiol, inhibin B).
  • Feedback Loop:
  • High testosterone inhibits GnRH, FSH, LH.
  • Low testosterone promotes increased GnRH → increased FSH & LH.



Testing FSH and LH in Men

  • When to Test:
  • Infertility
  • Low libido
  • Gynecomastia
  • Low testosterone
  • Suspected pituitary or testicular disorders
  • Reference Ranges (may vary by lab):
  • FSH: 1.5–12.4 mIU/mL
  • LH: 1.7–8.6 mIU/mL
  • Interpretation:
  • High FSH/LH with low testosterone: Primary hypogonadism (testicular failure)
  • Low/normal FSH/LH with low testosterone: Secondary hypogonadism (pituitary/hypothalamic issue)



Symptoms of Imbalance

  • Low FSH/LH:
  • Low libido
  • Infertility
  • Decreased muscle mass
  • Fatigue, depression
  • High FSH/LH:
  • Often compensatory due to testicular damage
  • Seen in Klinefelter syndrome, mumps orchitis, chemotherapy



Causes of Dysfunction

  • Low FSH/LH (Secondary Hypogonadism):
  • Brain injury, pituitary tumors
  • Prolactin excess (prolactinoma)
  • Chronic stress, opioids, anabolic steroids
  • Excessive obesity or insulin resistance
  • High FSH/LH (Primary Hypogonadism):
  • Testicular damage from trauma, chemo, radiation
  • Autoimmune orchitis
  • Genetic: Klinefelter syndrome
  • Other Factors:
  • Anabolic steroid abuse: Suppresses endogenous FSH/LH
  • Sleep deprivation: Decreases GnRH pulses
  • Elevated prolactin: Inhibits GnRH release



Associated Hormonal Interactions

  • Prolactin: High levels inhibit GnRH → low FSH/LH
  • Melatonin: Chronic circadian disruption may impact the hypothalamus
  • Insulin Resistance: Affects testicular function via inflammation and oxidative stress
  • Zinc: Essential for testosterone synthesis and sperm production



TRT and Other Treatment Options

  • Primary Hypogonadism:
  • TRT (topical, injection, pellet)
  • Fertility typically requires additional therapy (e.g., hCG + FSH)
  • Secondary Hypogonadism:
  • hCG monotherapy
  • hCG + FSH (if fertility is desired)
  • Clomiphene or Enclomiphene: stimulate endogenous LH/FSH production
  • Young Men: Prefer fertility-preserving treatments (Clomid, Enclomiphene, hCG)
  • Older Men: TRT may be appropriate if not trying to conceive



Supplements and Lifestyle Support

  • Zinc, Magnesium, Vitamin D
  • Ashwagandha, Tongkat Ali (natural LH boosters)
  • Omega-3s (reduce inflammation)
  • Adequate sleep, stress management
  • Resistance training (boosts testosterone naturally)



Fun Facts

  • LH surges also occur in women to trigger ovulation, but in men, it's a steady signal for testosterone.
  • Some bodybuilders use hCG during or after steroid cycles to prevent testicular atrophy.
  • LH and FSH are often tested in kids to evaluate puberty timing (precocious or delayed puberty).



Key Takeaway Maintaining optimal LH and FSH levels is essential for male reproductive, hormonal, and overall health. Testing is crucial in evaluating hypogonadism, infertility, or hormonal imbalance. Treatment is personalized based on cause, age, and fertility goals.

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