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Laboratory Medicine

Test Directory / Prolactin


Brown clotted serum, gel barrier

Common AbbreviationsPRL
Tube typeBrown clotted serum, gel barrier
Clinical IndicationConsistently elevated serum prolactin levels in the absence of pregnancy or postpartum lactation are indicative of hyperprolactinemia. This is the most common hypothalamic-pituitary dysfunction encountered in clinical endocrinology. Hyperprolactinemia often results in galactorrhea, amenorrhea and infertility in females and impotence and hypogonadism in males. Renal failure, hypothyroidism, and prolactin-secreting pituitary adenomas are common causes of abnormally elevated prolactin levels.
Specimen TypeBlood
Sample typeSerum
Minimum Volume0.5mL If requesting more than 10 tests please send an additional brown clotted serum sample.
Special PrecautionsNo special requirements
Stability 5 days at 20 - 25°C, 14 days at 2 - 8°C and 6 months at -20°C
Turnaround TimeInpatient: 48 hours Outpatient/ GP: 48 hours
Reference IntervalMales: 86 - 324 IU/L Females: 102 - 496 IU/L (Quoted by the manufacturer)
LimitationsAnalysis should not be performed on haemolysed, icteric or lipaemic samples. The assay is unaffected by biotin < 164 nmol/L or < 40 ng/mL. No interference was observed from rheumatoid factors up to a concentration of 1100 IU/mL. Samples should not be taken from patients receiving therapy with high biotin doses (i.e. > 5 mg/day) until at least 8 hours following the last biotin administration. In vitro tests were performed on 16 commonly used pharmaceuticals. No interference with the assay was found. In rare cases, interference due to extremely high titres of antibodies to analyte specific antibodies, streptavidin or ruthenium can occur. These effects are minimized by suitable test design. A number of publications report the presence of macroprolactin in the serum of female patients with various endocrinological diseases or during pregnancy. Differing degrees of detection of the serum macroprolactins relative to monomeric prolactin by various immunoassays have also been described. This could lead to a false diagnosis of hyperprolactinaemia depending on the immunoassay used. In case of implausible high prolactin values a precipitation by polyethylene glycol is recommended in order to estimate the amount of the biological active monomeric prolactin.
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