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