USMLE

Luteinizing Hormone (LH)

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Endocrine & Hormones
  1. Leptin
  2. Ghrelin
  3. Protein Hormones
  4. Steroid Hormones
  5. Insulin
  6. Diabetes
  7. Glucagon
  8. Epinephrine
  9. Cortisol
  10. Thyroid Hormones
  11. Calcitonin
  12. Parathyroid Hormone (PTH)
  13. Anterior Pituitary
  14. Prolactin
  15. Luteinizing Hormone (LH)
  16. Follicle-Stimulating Hormone (FSH)
  17. Growth Hormone (GH)
  18. Posterior Pituitary

Summary

Luteinizing hormone, or LH for short, is a protein hormone produced by the anterior pituitary gland. The anterior pituitary gland produces LH in response to upstream stimulation by GnRH, coming from the hypothalamus. Downstream, LH targets the testes and ovaries to stimulate the production of sex hormones: testosterone and estrogen. Both testosterone and estrogen play important roles in sexual development and reproduction.

Key Points

  • Luteinizing Hormone (LH)
    • Type: Peptide
    • Origin: Anterior Pituitary
    • Trigger: Stimulation by GnRH from hypothalamus
      • GnRH = Gonadotropin Releasing Hormone
    • Target: Testes and Ovaries
      • Effect: Stimulates release of
        • Testosterone from testes
        • Estradiol/Estrogen from ovaries
        • Testosterone and Estradiol are androgens involved in reproduction as well as the development of secondary sex characteristics (i.e. body hair, breast and genital growth, etc)
    • Feedback:
      • Estradiol usually inhibits LH release through negative feedback
      • Exception: Luteal Surge
        • During ovulation, Estradiol increases LH release through positive feedback
          • This causes spikes in both Estradiol and LH, which in turn causes ovulation.