LH
The Test
How is it used?
When is it requested?
LH and FSH may be measured when a boy or girl does not appear to be entering puberty at an appropriate age (either too late or too soon).
What does the test result mean?
Developmental defects:
- Ovarian agenesis (failure to develop ovaries)
- Chromosomal abnormality, such as Turner’s syndrome
- Ovarian steroidogenesis 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 levels will rise.
Low levels of FSH and LH are consistent with secondary ovarian failure due to a pituitary or hypothalamic problem.
In men, high FSH levels are 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 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.
Is there anything else I should know?
