Alpha subunit

Clinical Use
1 Detection and monitoring of functionless pituitary tumours.
There is some evidence that functionless pituitary tumours secrete increased quantities of the alpha-subunit common to pituitary glycoprotein hormones.

2 Detection and monitoring of glycoprotein hormone-secreting adenomas e.g. TSH, LH/FSH.

3 Detection and monitoring of malignant gastroenteropancreatic tumours.

Patient Preparation
None. Take blood (5 mL) using a plain vacutainer or syringe.

Sample Preparation
Transfer the blood to a plain tube and allow to clot. Separate the serum and store at -20C. Send serum (2 mL) to the SAS laboratory. Comprehensive clinical and laboratory information should accompany each request – TSH,LH and FSH results as appropriate and indication of renal function.

Reference Range
Adult (Female and Male) < 1.0 IU/L
Post-menopause and mid-cycle < 3.0 IU/L

Raised values for the common a-subunit are also found after the menopause, in renal failure, hypothyroidism, Cushing’s syndrome, pregnancy and in some patients with malignancies of breast or pancreas.

Centres offering this assay
Birmingham University Hospital Endocrine Laboratory,

References
Grossman M, Trautman ME, Poer HS et al. Alpha-subunit and human chorionic gonadotropin-b immunoreactivity in patients with malignant endocrine gastroenteropancreatic tumours. Eur J Clin Invest 1994; 24: 131-6.

Beck-Peccoz P, Persani L. Thyrotropinomas. Endocrinol Metab Clin N Am 2008; 37:123-134.

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