Gonadotropin Alpha subunit

Diagnostic Use

Free Alpha Subunit measurement may assist in the diagnosis of some pituitary tumours. Overall, 5-30% of pituitary adenomas may show elevation in serum ASU and not exclusively TSH secreting adenomas.

Free Alpha Subunits may also help to differentiate TSH secreting adenoma (where elevated) from thyroid hormone resistance, both conditions where TSH may be inappropriately high for the level of thyroid hormones in the circulation.

Please note this test is NOT the same as Gonadotrophins (LH and FSH). All requests will be vetted by our Chemical Pathologist prior to analysis.

Department

Endo/Steroid Lab

Delphic Registration Code

ASU

Synonyms

Alpha subunit
ASU
hCG Alpha

Turnaround Time

16 weeks

Test Code

6502

Specimen Type

• Serum
• Plasma

Specimen Requirements

Tube/Container Type:

Preferred

• Serum (Red Cap)
• SST II (Gold Cap)

Acceptable

• Lithium Heparin - Gel (Green Cap)

Preferred Sample Volume (ml)

4

No of Samples Required

1

Additional Specimen Information

Separate immediately. Store frozen.

Aliquot Instructions

Sample Type

• Serum
• Plasma

Minimum Volume (ml)

0.5

Transport to Lab

Frozen
If overnight - Frozen

Additional Referral/Aliquot Information

Minimum 0.5 mL Plasma or Serum, preferably 1 mL Plasma or Serum. Freeze.

Interpretation

To use as a tumour marker for some pituitary adenomas, including non-functioning pituitary adenomas whereby hormone levels are not increased.

To help differentiate TSHoma from thyroid hormone resistance.

Please note ASU elevation may be seen in women close to the time of ovulation and post-menopause (where elevated LH, FSH).

Pregnancy is also associated with marked elevations, paralleling hCG elevation – ASU should not be ordered on pregnant patients.

Cross-reactivity (of ASU) may also be seen in hypothyroid patients with elevated TSH.

Marked ASU elevation may also be seen in patients with end-stage renal failure.

 

Reference Intervals

Males             Pre-menopausal      Post-menopausal                      

0-0.7 IU/L            0-0.6 IU/L                    0-1.3 IU/L

Test Method

IRMA (Beckman Coulter)

Contact Canterbury Health Laboratories on +64 3 364 0484 or email LabInfo@cdhb.health.nz

Billing Code

6502

Contact Information

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