LH Test

LH is often used in conjunction with other tests (FSH, testosterone, oestradiol and progesterone) in the investigation of infertility in both men and women. LH measurements are also useful in the investigation of menstrual irregularities (irregular periods) and to aid in the diagnosis of pituitary gland disorders. In children, FSH and LH are used to diagnose delayed and precocious (early) puberty.

In women: Days 1-5 of the menstrual cycle (during menstruation or bleeding)
In men: Samples can be taken at any time
In children: Samples can be taken at any time. Sometimes sampling for LH and FSH happens after an injection of gonadotrophin releasing hormone (GnRH). This stimulates the pituitary gland to produce LH and FSH.

In women, FSH and LH results can help to tell the difference between primary ovarian failure (failure of the ovaries themselves) and secondary ovarian failure (failure of the ovaries due to disorders of either the pituitary gland or the hypothalamus in the brain). Increased FSH and LH are consistent with primary ovarian failure. Some causes of primary ovarian failure are listed below.

Developmental defects:

• Ovarian agenesis (failure to develop ovaries) 
• Chromosomal abnormality, such as Turner’s syndrome
• Ovarian steroidogenesis (steroid hormone production) defect, such as 17 alpha hydroxylase deficiency

Premature ovarian failure due to: 

• Radiation therapy 
• Chemotherapy 
• Autoimmune disease

Chronic anovulation (failure to ovulate) due to: 

• Polycystic ovary syndrome (PCOS)
• Adrenal disease 
• Thyroid disease 
• Ovarian tumour

When a woman enters the menopause and her ovaries stop working, FSH and LH will rise. Note that LH should not be measured specifically to diagnose the menopause. In women above the age of 45 menopause can usually be diagnosed clinically. In younger women, and for investigation of premature ovarian insufficiency, FSH is the appropriate test.

Low FSH and LH are consistent with secondary ovarian failure due to a pituitary or hypothalamic problem.

In men, LH controls the production of testosterone from the testes and FSH controls the production of sperm. High LH and FSH may be due to primary testicular failure. This can be due to developmental defects in testicular growth or to testicular injury, as indicated below.

Developmental defects: 

• Gonadal agenesis (failure to develop testes) 
• Chromosomal abnormality, such as Klinefelters syndrome

Testicular failure:

• Viral infection (mumps) 
• Trauma 
• Radiation therapy 
• Chemotherapy 
• Autoimmune disease 
• Germ cell tumour

Low levels of LH and FSH are consistent with pituitary or hypothalamic disorders.

In young children, high levels of FSH and LH and development of secondary sexual characteristics at an unusually young age are an indication of precocious (early) puberty. This is much more common in girls than in boys.

LH results can be increased with use of certain drugs, such as cimetidine, clomiphene, digitalis, and levodopa. LH results can decrease with oral contraceptives (the pill), phenothiazines, and other hormone treatments.

The basic test for infertility is measurement of progesterone to check that ovulation is occurring. Other tests for infertility include FSH and LH and other blood tests to assess your reproductive hormone levels. A post-coital test may be carried out where the cervical mucous is examined 2-8 hours after intercourse to check if the sperm are surviving in it. A hysterosalpingogram (image of fallopian tubes) may be done to see whether your fallopian tubes are blocked. Your partner may be asked to give a specimen of semen for analysis.