Decreased FSH

Follicle-stimulating hormone (FSH) concentration below the age-, sex-, and phase-specific reference range.

• Adult men

  • Normal range: 1.5 - 12.4 mIU/mL (or IU/L)

• Adult women

  • Follicular phase (Day 2-3): 3.0 - 10.0 mIU/mL

  • Ovulatory peak phase: 4.5 - 22.5 mIU/mL

  • Luteal phase: 1.8 - 5.1 mIU/mL

  • Postmenopause: 25.8 - 134.8 mIU/mL

Causes

• Impaired hypothalamic GnRH secretion

• Pituitary disorders

  • Pituitary tumor/cysts (prolactinoma)

  • Pituitary trauma

    • Surgery

    • Radiation

    • Hemorrhage

    • Ischemia

• Severe stress

• Medications

  • Birth control pills

  • Testosterone replacement therapy

  • Chemotherapy

• Kallmann syndrome

• Pregnancy

• Severe systemic illness

  • Hypothyroidism

  • Poorly managed diabetes

  • Chronic inflammatory disease