Alpha-Subunit Pituitary Tumor Marker, Serum
Use
The Alpha-Subunit Pituitary Tumor Marker is used as an adjunct in the diagnosis of pituitary tumors and in the follow-up of treated pituitary tumor patients. It is particularly useful in the differential diagnosis of thyrotropin-secreting pituitary tumor versus thyroid hormone resistance, as well as constitutional delay of puberty versus hypogonadotrophic hypogonadism. This test measures the free alpha subunit, which may be overproduced by pituitary adenomas and provides clinical insight into pituitary endocrine activity.
Special Instructions
This test should not be ordered on pregnant patients due to physiological elevations in serum free alpha-subunit levels during pregnancy. Clinical interpretation of results can be influenced by improper specimen collection, handling, and interfering substances such as TSH cross-reactivity in cases of elevated thyrotropin and elevations due to kidney failure or ovarian hyperstimulation.
Limitations
False-positive elevation in serum free alpha-subunit may occur if blood specimens are drawn within 24 hours of ovulation or in patients with kidney failure. The test should be interpreted with caution in patients with elevated TSH due to potential cross-reactivity. The test is not suitable for use in pregnant patients as it results in physiological elevations of serum free alpha-subunits. Additionally, thyrotropin-releasing hormone and gonadotropin-releasing hormone testing should be conducted in specialized clinical settings.
New York Approved
Methodology
Immunoassay (CLIA)
Biomarkers
LOINC Codes
- 14170-5
- 14170-5
Result Turnaround Time
2-8 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.35 mL
Container
Plastic vial
Collection Instructions
Centrifuge and aliquot serum into a plastic vial
Storage Instructions
Store frozen for up to 90 days or refrigerated for up to 7 days.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 7 days |
| Frozen | 90 days |