Lab marker · Also: luteinizing hormone

LH

A pituitary hormone whose mid-cycle surge triggers ovulation.

A pituitary hormone whose mid-cycle surge triggers ovulation.

Also known as: luteinizing hormone

Luteinizing hormone (LH) is made by the pituitary gland. A surge in LH around mid-cycle triggers the release of an egg (ovulation).

The ratio of LH to FSH is one of several data points clinicians may consider when evaluating menstrual irregularity or conditions such as PCOS.

Related terms

FSH

A pituitary hormone that stimulates ovarian follicles and rises as ovarian reserve declines.

Ovulation

The release of a mature egg from the ovary, usually around the middle of the menstrual cycle.

Follicular phase

The first half of the menstrual cycle, when a follicle matures and estrogen rises.

PCOS

A common hormonal condition marked by irregular ovulation, androgen excess, and/or polycystic ovaries.

Source

MedlinePlus: LH Levels Test

← Back to full glossary