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Test Code MCRPL Macroprolactin, Serum

Performing Laboratory

Mayo Medical Laboratories in Rochester

Reporting Name

Macroprolactin, S

Specimen Type

Serum


Specimen Required


Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 1 mL

Collection Instructions: Spin down and separate serum from clot.

Additional Information: Twelve hours before this blood test, do not take multivitamins or dietary supplements containing biotin or vitamin B7 that are commonly found in hair, skin and nail supplements and multivitamins.


Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

NA

Other

NA

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Frozen  180 days

Specimen Minimum Volume

0.6 mL

Day(s) and Time(s) Performed

Monday through Friday 5 a.m. – 12 a.m., Saturday 6 a.m. – 6 p.m.

Specimen Retention Time

3 months

Analytic Time

Same day/1 day

Reference Values

TOTAL PROLACTIN

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

 

Percent of the precipitated (complexed) prolactin fraction of the total prolactin <50% (considered negative for macroprolactin)

 

Unprecipitated prolactin levels are expected to be within the total prolactin reference range.

Useful For

Determining biologically active levels of prolactin, in asymptomatic patients with elevated prolactin levels

 

Ruling out the presence of macroprolactin

Method Name

TOPRL: Electrochemiluminescent Immunoassay

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

Test Classification

This test has been cleared or approved by the U.S. 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 In Process

 

Result ID Test Result Name Result LOINC Value
PROU Prolactin,Unprecipitated,S 38926-2
T_PRL Prolactin,Total,S 2842-3
RATIO Percent 51441-4
CMT42 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 level rises in response to physiologic stimuli such as nipple stimulation, sleep, exercise, sexual intercourse, and hypoglycemia. 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 percentage of the precipitated prolactin (complexed) fraction of total prolactin is <50%, 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 percentage of the precipitated (complexed) prolactin fraction of total prolactin is ≥50%, the specimen is considered positive for the presence of macroprolactin.

 

Following macroprolactin precipitation, a patient whose unprecipitated prolactin level is greater than the upper limit of the total prolactin reference range may have hyperprolactinemia.

 

See PRL/8690 Prolactin, Serum for interpretation of prolactin levels.

Cautions

Twelve hours before this blood test, do not take multivitamins or dietary supplements containing biotin or vitamin B7 that are commonly found in hair, skin and nail supplements and multivitamins.

 

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.

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;62:633-643

Method Description

The instrument use for testing is the Roche Cobas 6000. An equal volume of 25% polyethylene glycol (PEG) is added to a serum prolactin sample causing the biologically inactive form of prolactin (macroprolactin) to precipitate. Following centrifugation, prolactin is measured in the supernatant (containing unprecipitated prolactin), as well as in an aliquot of the native sample. Precipitated prolactin is calculated by subtracting the unprecipitated prolactin value from the total prolactin. The percentage of precipitated prolactin to total prolactin indicated the presence or absence of macroprolactin.(Package insert: Elecsys and Modular Prolactin II, Roche 2005)

Profile Information

Test ID Reporting Name Available Separately Always Performed
TOPRL Prolactin,Total,S Yes, (order PRL) Yes
PEGPR Prolactin,Unprecipitated,S No Yes