Prolactin, Pituitary Macroadenoma, Serum
Use
Useful for quantifying prolactin in serum specimens where the high-dose hook effect is suspected (e.g., presence of pituitary tumor with symptoms of prolactinoma and lower than expected serum prolactin concentration).
Special Instructions
A pituitary adenoma should be identified via imaging studies before ordering this test. Venipuncture can raise prolactin levels; thus, it's recommended to insert a heparinized scalp vein followed by a 30-minute rest before drawing the sample. Draw samples between 8 a.m. and 10 a.m. to ensure accuracy.
Limitations
Moderate prolactin elevation may occur with large nonfunctioning adenomas due to decreased dopamine levels, which usually inhibit prolactin secretion. Patients on high doses of biotin (>5 mg/day) should have samples taken at least eight hours after the last administration to avoid interference. Samples taken from patients treated with monoclonal mouse antibodies or those with high titers of antibodies to ruthenium or streptavidin may yield erroneous results.
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 2842-3
Result Turnaround Time
3-4 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1.5 mL
Minimum Volume
1 mL
Container
Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.
Collection Instructions
If a red-top tube or plasma tube is used, transfer separated serum or plasma to a plastic transport tube. Venipuncture itself can elevate prolactin level. Therefore, some recommend insertion of heparinized scalp vein followed by a 30-minute rest before sample is drawn. Draw between 8 a.m. and 10 a.m. (levels subsequently increase).
Storage Instructions
Refrigerate.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 14 days |
| Frozen | 14 days |