Alpha subunit (ASU)

Chemical Pathology

Notes

Please note: this test is only requestable by the endocrine consultants.

The measurement of alpha subunit of TSH may be helpful in distinguishing between a TSH-secreting pituitary adenoma and thyroid hormone resistance in patients with a high TSH and FT4. TSH-secreting adenomas are rare and make up 1% of pituitary tumours.

Sample requirements

For adults, blood taken into a 6mL red top tube

Storage/transport

Do not store. Send at ambient temperature to the laboratory on the day of sample collection.

Required information

Relevant clinical details including reason for the request.

Turnaround times

Samples are sent for analysis to Queen Elizabeth Hospital, Birmingham with results expected back within 2 weeks.

Reference ranges

 Adult (male & female) < 1 IU/L

Post-menopausal & mid cycle <3 IU/L

Note: In pregnancy there is 0.1% cross-reactivity with hCG.

Further information

To learn more access Supra Regional Assay Service  

Page last updated: 12/02/2015