Alpha subunit

Specimen:

5 mL blood in plain tube.

Method:

Immunoassay.

Reference Interval:

Female

Premenopausal: < 1.0 IU/L

Postmenopausal: < 2.0 IU/L

Levels in pregnancy may be: > 2.0 IU/L

Male: < 0.6 IU/L

Application:

Detection of endocrine tumours secreting only the free α chains of the glycoprotein hormones (LH, FSH, hCG, TSH) are useful for TSHomas which may produce intact TSH and free alpha subunit.

Interpretation:

Some neuroendocrine and pituitary tumours secrete little or no intact hormone, but produce the common α subunit of glycoprotein hormones, at times in massive amounts.

Reference:

Lamberts SW et al. Front Neuroendocrinol 2001; 22(4): 309-339.