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Luteinizing Hormone (LH) is a glycoprotein gonadotropic hormone. It is synthesized by basophilic cells under the influence of the hypothalamic releasing factor in the anterior pituitary gland.

In women, LH stimulates the synthesis of estrogens, regulates progesterone secretion, and supports corpus luteum formation. A critical level of LH triggers ovulation. In men, LH stimulates the synthesis of SHBG (sex hormone-binding globulin) and increases the permeability of seminiferous tubules, leading to an increase in plasma testosterone levels. In men, LH levels tend to rise between the ages of 60-65.

The secretion of hormones occurs in a pulsatile manner and depends on the phase of the menstrual cycle in women. The LH peak occurs during ovulation, followed by a decrease, remaining lower throughout the luteal phase compared to the follicular phase. LH levels also decrease during pregnancy. LH and FSH levels increase postmenopause.

The LH/FSH ratio is an important indicator. Normally, it is 1 before menarche, varies from 1 to 1.5 one year after menarche, and from 1.5 to 2 two years after menarche until menopause.

  • The analysis is performed on a blood sample drawn from a vein.
  • The test should be taken after 8–14 hours of fasting.
  • Three days before the test, physical exertion, psycho-emotional stress, and alcohol consumption should be avoided.
  • If no specific testing date is prescribed by the attending physician, women with a menstrual cycle should take the test on days 2–4 of the cycle.
  • Hirsutism
  • Decreased libido and potency
  • Anovulation
  • Oligomenorrhea and amenorrhea
  • Infertility
  • Dysfunctional uterine bleeding
  • Sexual infantilism
  • Endometriosis
  • Polycystic ovary syndrome
  • Evaluation of hormone therapy effectiveness
  • Delayed or premature sexual development

Causes of Elevated LH Levels:

  • Basophilic pituitary adenoma
  • Endometrial ovarian cyst
  • Turner syndrome
  • Testicular feminization
  • Dysfunctional uterine bleeding
  • Kidney failure
  • Use of certain medications, such as:
    • Releasing hormone
    • Ketoconazole
    • Levodopa
    • Nafarelin
    • Naloxone
    • Phenytoin
    • Pravastatin
    • Tamoxifen
  • Endometriosis
  • Fasting
  • Physical exercise

Causes of Decreased LH Levels:

  • Secondary amenorrhea
  • Pituitary dwarfism
  • Sheehan’s syndrome
  • Simmonds’ disease
  • Marfan syndrome
  • Hyperprolactinemia
  • Atypical form of polycystic ovary syndrome
  • Stress
  • Obesity
  • Surgical intervention
  • Luteal phase deficiency
  • Smoking
  • Use of certain medications, such as:
    • Anabolic steroids
    • Buserelin
    • Carbamazepine
    • Megestrol
    • Oral contraceptives
    • Stanozolol