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Test ID MCRPL Macroprolactin, Serum

Reporting Name

Macroprolactin, S

Useful 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

Specimen Type


Specimen 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.


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL

Collection Instructions: Spin down and separate serum from clot.

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

Reference Values



<18 years: not established

≥18 years: 4.0-15.2 ng/mL


<18 years: not established

≥18 years: 4.8-23.3 ng/mL




<18 years: not established

≥18 years: 2.7-13.1 ng/mL


<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

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

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.


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.

Clinical Reference

1. Fahie-Wilson M: In Hyperprolactinemia, Testing for Macroprolactin is Essential. Clin Chem 2003;49(9):1434-1436

2. Gibney J, Smith TP, McKenna TJ: Clinical relevance of macro-prolactin. Clin Endocrinol 2005 Jun;62:633-643

Report Available

Same day/1 to 3 days

Method Name

TOPRL: Electrochemiluminescent Immunoassay

PEGPR: Polyethylene Glycol (PEG) Precipitation Followed by Electrochemiluminescent Immunoassay


If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.