Test Catalog

Test ID: LH    
Luteinizing Hormone (LH), Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

An adjunct in the evaluation of menstrual irregularities


Evaluating patients with suspected hypogonadism


Predicting ovulation


Evaluating infertility


Diagnosing pituitary disorders

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Luteinizing hormone (LH) is a glycoprotein hormone consisting of 2 non-covalently bound subunits (alpha and beta). The alpha subunit of LH, follicle-stimulating hormone (FSH), thyrotropin (formerly known as thyroid-stimulating hormone: TSH), and human chorionic gonadotropin (hCG) are identical and contain 92 amino acids. The beta subunits of these hormones vary and confer the hormones' specificity. LH has a beta subunit of 121 amino acids and is responsible for interaction with the LH receptor. This beta subunit contains the same amino acids in sequence as the beta subunit of hCG, and both stimulate the same receptor; however, the hCG-beta subunit contains an additional 24 amino acids, and the hormones differ in the composition of their sugar moieties. Gonadotropin-releasing hormone from the hypothalamus controls the secretion of the gonadotropins, FSH, and LH, from the anterior pituitary.


In both males and females, LH is essential for reproduction. In females, the menstrual cycle is divided by a midcycle surge of both LH and FSH into a follicular phase and a luteal phase. This "LH surge" triggers ovulation thereby not only releasing the egg, but also initiating the conversion of the residual follicle into a corpus luteum that, in turn, produces progesterone to prepare the endometrium for a possible implantation. LH is necessary to maintain luteal function for the first 2 weeks. In case of pregnancy, luteal function will be further maintained by the action of hCG (a hormone very similar to LH) from the newly established pregnancy. LH supports thecal cells in the ovary that provide androgens and hormonal precursors for estradiol production. LH in males acts on testicular interstitial cells of Leydig to cause increased synthesis of testosterone.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


< or =4 weeks: Not established

>1 month-< or =12 months: < or =0.4 IU/L

>12 months-< or =6 years: < or =1.3 IU/L

>6-< or =11 years: < or =1.4 IU/L

>11-< or =14 years: 0.1-7.8 IU/L

>14-< or =18 years: 1.3-9.8 IU/L

>18 years: 1.3-9.6 IU/L



< or =4 weeks: Not established

>1-< or =12 months: < or =0.4 IU/L

>12 months-< or =6 years: < or =0.5 IU/L

>6-< or =11 years: < or =3.1 IU/L

>11-< or =14 years: < or =11.9 IU/L

>14-< or =18 years: 0.5-41.7 IU/L



Follicular: 1.9-14.6 IU/L

Midcycle: 12.2-118.0 IU/L

Luteal: 0.7-12.9 IU/L

Postmenopausal: 5.3-65.4 IU/L

Interpretation Provides information to assist in interpretation of the test results

In both males and females, primary hypogonadism results in an elevation of basal follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels.


Postmenopausal LH levels are generally above 40 IU/L.


FSH and LH are generally elevated in:

- Primary gonadal failure

- Complete testicular feminization syndrome

- Precocious puberty (either idiopathic or secondary to a central nervous system lesion)

- Menopause

- Primary ovarian hypodysfunction in females

- Polycystic ovary disease in females

- Primary hypogonadism in males


LH is decreased in:

- Primary ovarian hyperfunction in females

- Primary hypergonadism in males


FSH and LH are both decreased in failure of the pituitary or hypothalamus.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No clinically significant cross-reactivity has been demonstrated with follicle-stimulating hormone (FSH), thyrotropin (TSH), or human chorionic gonadotropin (hCG).


Some patients who have been exposed to animal antigens, either in the environment or as part of treatment or imaging procedures, may have circulating anti-animal antibodies present. These antibodies may interfere with the assay reagents to produce unreliable results.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Kaplan LA, Pesce AJ: The gonads. In: Kazmierczak SC, ed. Clinical Chemistry: Theory, Analysis, and Correlation. 3rd ed. Mosby-Year Book, Inc; 1996:894

2. Dumesic DA: Hyperandrogenic anovulation: a new view of polycystic ovary syndrome. Postgrad Ob Gyn. 1995;15:1-5

3. Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018