Luteinising Hormone (LH)

Clinical Chemistry

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Description

Human luteinising hormone ( LH ) is a glycoprotein hormone with two dissimilar subunits ( alpha and beta ). LH has a molecular weight of approximately 30,000 daltons. The a-subunit of LH contains 92 amino acid residues and is essentially identical to the a-subunits of follicle stimulating hormone ( FSH ), thyroid stimulating hormone ( TSH ), and human chorionic gonadotrophin ( hCG ). The b-subunit of LH contains 112 amino acid residues and is considerably different from that of FSH and TSH. However, the b -subunits of LH and hCG are very similar. The structural similarities between LH and hCG are responsible for the observed similarity in biological properties. In the menstrual cycle, LH secretion causes secretion of oestrogens and a surge in LH production caused by a switch to positive feedback by oestradiol leads to ovulation. The primary role of LH in the male is to stimulate the production of testosterone by the Leydig cells. LH, through the production of testosterone together with FSH, regulates spermatogenesis in the Sertoli cells of the seminiferous tubules of the testes. Testosterone exerts a negative feedback on the release of LH.

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Indications

Males and females: investigation of infertility and assessment of pituitary function. Females: menstrual irregularities, measure on day 2 of cycle. Males: investigation of gonadal failure ( low testosterone ).

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Sample Type

Serum, SST, Gel, minimum 2mL ( 1mL separated serum ).

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Reference Range

Reference ranges are provided on the report. Alternatively, please contact the laboratory for current ranges.

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Turnaround Time

Within 3 days

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Testing Frequency

As required.

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