Luteinizing Hormone

Category:

Luteinizing Hormone

Description

Luteinizing hormone (LH) is produced by the pituitary gland. Control of LH production is a complex system involving hormones produced by the gonads (ovaries or testes), the pituitary, and the hypothalamus.

Women’s menstrual cycles are divided into 2 phases, the follicular and luteal, by a mid-cycle surge of follicle-stimulating hormone (FSH) and LH. The high level of LH (and FSH) at mid-cycle triggers ovulation.

In men, LH stimulates the Leydig cells in the testes to produce testosterone.

In children, LH levels rise shortly after birth and then fall to very low. At about 6-8 years, levels again rise before the beginning of puberty.

LH is used together with other tests (FSH, testosterone, estradiol and progesterone) in the study  of infertility in both men and women. LH levels are also useful in the investigation of menstrual irregularities, diagnosis of pituitary disorders or diseases involving the ovaries or testes.
In children, FSH and LH are used to diagnose delayed and precocious (early) puberty.
Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.

Purpose of the test

To meassure the level of Luteinizing Hormone in order to evaluate pituitary function, especially in terms of fertility issues.

It is prescribed when the patient is having difficulty getting pregnant or is having irregular menstrual periods.   Also if doctor sees symptoms of a pituitary or hypothalamic disorder or symptoms of ovarian or testicular disease. Also when a doctor suspects that a child has delayed or earlier than expected sexual maturation.

In women and men, LH (along with FSH) is ordered as part of the workup of infertility and pituitary or gonadal disorders.

Reference range values

Male Adult             1 – 8 U/L
Female
Follicular               1 – 12 U/L
Mid-Cycle Peak    17 - 77 U/L
Luteal                    0 - 15 U/L
Post menopausal  11 - 40 U/L

Abnormal findings

High levels of LH and FSH are seen in primary ovarian failure whose causes can be :
• Ovarian agenesis (failure to develop ovaries) 
• Chromosomal abnormality, such as Turner’s syndrome
• Ovarian steroidogenesis defect such as 17 alpha hydroxylase deficiency
• Radiation
• Chemotherapy
• Autoimmune disease
• Polycystic ovary syndrome (PCOS)
• Adrenal disease 
• Thyroid disease 
• Ovarian tumor
When a woman enters menopause , LH levels will rise.

Low levels of LH and FSH are seen in secondary ovarian failure and indicate a problem in the pituitary or hypothalamus.
In men, high LH levels indicate primary testicular failure. This can be due to:
• Gonadal agenesis 
• Chromosomal abnormality, such as Klinefelters syndrome
• Viral infection (mumps) 
• Trauma 
• Radiation 
• Chemotherapy 
• Autoimmune disease 
• Germ cell tumor
Low levels are consistent with pituitary or hypothalamic disorders.

In young children, high levels of LH and FSH are indication of precocious puberty. Some of the causes may be:
• Central nervous system lesions
• Hormone-secreting tumors
• Ovarian tumors or cysts
• Testicular tumors
On the contrary, low levels of LH and FSH indicate delayed puberty, cause by:
• Gonadal (ovary or testes) failure
• Hormone deficiency
• Turner’s syndrome (chromosomal abnormality in girls)
• Klinefelter’s syndrome (chromosomal abnormality in boys)
• Chronic infections
• Cancer
• Eating disorder (anorexia nervosa)