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HelpTest Code MCRPL Macroprolactin, Serum
Reporting Name
Macroprolactin, SUseful For
Determining biologically active levels of prolactin, in asymptomatic patients with elevated prolactin levels
Ruling out the presence of macroprolactin
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| TOPRL | Prolactin,Total,S | Yes, (order PRL) | Yes |
| PEGPR | Prolactin,Unprecipitated,S | No | Yes |
Method Name
TOPRL: Electrochemiluminescent Immunoassay
PEGPR: Polyethylene Glycol (PEG) Precipitation Followed by Electrochemiluminescent Immunoassay
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Patient Preparation: For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.6 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 90 days | ||
| Ambient | 24 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
Reference Values
PROLACTIN, TOTAL
Males
<18 years: not established
≥18 years: 4.0-15.2 ng/mL
Females
<18 years: not established
≥18 years: 4.8-23.3 ng/mL
PROLACTIN, UNPRECIPITATED
Males
<18 years: not established
≥18 years: 2.7-13.1 ng/mL
Females
<18 years: not established
≥18 years: 3.4-18.5 ng/mL
When the percent of the precipitated (complexed) prolactin fraction of the total prolactin is 60% or less, the result is considered negative for macroprolactin.
Day(s) Performed
Monday through Sunday
CPT Code Information
84146 x 2
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| MCRPL | Macroprolactin, S | 78993-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| PROU | Prolactin,Unprecipitated,S | 38926-2 |
| T_PRL | Prolactin,Total,S | 20568-2 |
| RATIO | Prolactin, Percent PEG-precipitated | 51441-4 |
| CMT42 | Interpretive Comment | 48767-8 |
Clinical Information
Prolactin is secreted by the anterior pituitary gland under negative control by dopamine, which is secreted by the hypothalamus. The only physiological function of prolactin is the stimulation of milk production. In normal individuals, the prolactin concentration in blood rises in response to physiologic stimuli such as nipple stimulation, sleep, exercise, sexual intercourse, and hypoglycemia. Certain medications, (eg, phenothiazines, metoclopramide, risperidone, selective serotonin reuptake inhibitors, estrogens, verapamil) may also cause hyperprolactinemia. Pathologic causes of hyperprolactinemia include prolactin-secreting pituitary adenoma (prolactinoma), diseases of the hypothalamus, primary hypothyroidism, section compression of the pituitary stalk, chest wall lesions, renal failure, and ectopic tumors.
Hyperprolactinemia may also be caused by the presence of a high-molecular-mass complex of prolactin called macroprolactin (typically due to prolactin bound to immunoglobulin). In this situation, the patient is asymptomatic. Hyperprolactinemia attributable to macroprolactin is a frequent cause of misdiagnosis and mismanagement of patients. Macroprolactin should be considered if, in the presence of elevated prolactin levels, signs and symptoms of hyperprolactinemia are absent, or pituitary imaging studies are not informative.
Interpretation
When the fraction (percentage) of polyethylene glycol (PEG)-precipitated (complexed) prolactin is 60% or less of total prolactin, the specimen is considered negative for macroprolactin. When total prolactin exceeds the upper reference limit and macroprolactin is negative, other causes for hyperprolactinemia should be explored.
When the fraction (percentage) of polyethylene glycol (PEG)-precipitated (complexed) prolactin is above 60%, the specimen is considered positive for the presence of macroprolactin.
Following polyethylene glycol (PEG)-precipitation, a patient whose unprecipitated prolactin concentration is greater than the upper limit of the unprecipitated prolactin reference interval may have hyperprolactinemia.
See PRL / Prolactin, Serum for interpretation of prolactin levels.
Cautions
Demonstration of the presence of macroprolactin does not exclude the possibility of concomitant presence of pituitary adenoma. Results should be interpreted in conjunction with clinical findings.
Method Description
TOPRL:
The Roche cobas e immunoassay Prolactin II method employs 2 monoclonal antibodies specifically directed against prolactin. A biotinylated monoclonal antibody and a second monoclonal antibody labeled with a ruthenium complex react with prolactin in the sample to form a sandwich complex. After the addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin. Application of a voltage to the electrode then induces chemiluminescent emission, which is measured.(Package insert: Elecsys Prolactin II, V 8.0, Roche 2017)
PEGPR:
Macroprolactin and oligomers can be precipitated by using a 25 % aqueous PEG solution (ratio 1+1). After centrifugation, the supernatant containing monomeric prolactin is used in the Elecsys Prolactin II assay in the same way as a native sample. The dilution effect which occurs during sample pretreatment and the coprecipitation of monomeric prolactin must be taken into consideration. Precipitated prolactin is calculated by subtracting the unprecipitated prolactin value from the total prolactin. The percentage of precipitated prolactin to total prolactin indicates the presence or absence of macroprolactin.(Package insert: Elecsys Prolactin II, V 8.0, Roche 2017)