Prolactin, Pituitary Macroadenoma, Serum
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Identifying patients with pituitary macroprolactinomas
Quantifying prolactin in specimens where the high-dose hook effect is suspected (eg, presence of pituitary adenoma with symptoms of prolactinoma, and lower than expected prolactin level)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Prolactin, Pituitary Macroadenoma
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 0.6 mL
Collection Instructions: This assay must have its own vial.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Mild OK; Gross reject
Mild OK; Gross OK
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Serum||Refrigerated (preferred)||7 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Prolactin is secreted by the anterior pituitary gland. The major chemical controlling prolactin secretion is hypothalamic dopamine, which inhibits pituitary prolactin secretion.
In normal individuals, the prolactin level rises in response to physiologic stimuli, such as sleep, exercise, nipple stimulation, sexual intercourse, hypoglycemia, postpartum period, and birth. Pathologic causes of hyperprolactinemia include prolactin-secreting pituitary adenoma (prolactinoma), functional and organic disease of the hypothalamus, primary hypothyroidism, section compression of the pituitary stalk, chest wall lesions, renal failure, and ectopic tumors. Prolactinomas are 5 times more frequent in females than males.
Prolactin-secreting macroadenomas (>10 mm in diameter) can sometimes produce exceedingly high serum prolactin concentrations that may paradoxically result in falsely-low prolactin concentrations when measured by immunometric assays. In such situations, very high concentrations of prolactin saturate both the capture and signal antibodies in the assay, block formation of the capture antibody-prolactin-signal antibody "sandwich," and result in falsely-decreased prolactin results (referred to as the high-dose hook effect). With such tumors, serum prolactin levels may be falsely decreased into the normal reference interval, potentially resulting in inappropriate patient management. Dilution of the specimen eliminates the analytic artifact in these cases.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Males: 3-13 ng/mL
Females: 3-27 ng/mL
Significantly increasing concentrations of prolactin, obtained after dilution of the serum, is consistent with high concentrations of prolactin secreted by functional macroprolactinomas.
Serum prolactin levels >250 ng/mL are usually associated with prolactin-secreting tumors, whereas moderately increased levels of serum prolactin are not a reliable guide for determining whether a prolactin-producing pituitary adenoma is present.
Slight nonlinearities detected in the prolactin dilution series may indicate interference by macroprolactin (prolactin bound to immunoglobulin). In these situations, patients are asymptomatic. Apparent hyperprolactinemia attributable to macroprolactin is a frequent cause of misdiagnosis and mismanagement of patients.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not useful for initial patient assessment; order PRL/85670 Prolactin, Serum as the initial screening test.
A pituitary adenoma should be identified by imaging studies prior to ordering this test.
A macroadenoma may be nonfunctional and not secrete prolactin.
Infrequently, a patient may have a nonfunctional macroadenoma but apparent hyperprolactinemia caused by the presence of macroprolactin. To determine this, order MCRPL/87843 Macroprolactin, Serum.
Multiple medications can cause a rise in prolactin levels, including phenothiazines and other anti-psychotic drugs, metoclopramide, opiates, amphetamines, alpha-methyl dopa, estrogen, and cimetidine.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
St-Jean E, Blain F, Comotois R: High prolactin levels may be missed by immunoradiometric assay in patients with macroprolactinomas. Clin Endocrinol 1996 Mar;44(3):305-309
Method Description Describes how the test is performed and provides a method-specific reference
This assay is performed on the Beckman Coulter UniCel DXI 800 instrument using the Access Prolactin assay, a simultaneous 1-step immunoenzymatic sandwich assay. Sample is added to a reaction vessel along with polyclonal goat anti-prolactin (anti-PRL) alkaline phosphatase conjugate, and paramagnetic particles coated with mouse monoclonal anti-PRL antibody. Prolactin in the sample binds to the monoclonal anti-PRL on the solid phase, while the goat anti-PRL-alkaline phosphatase conjugate reacts with a different antigenic site on the sample prolactin. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field, while unbound materials are washed away. The chemiluminescent substrate Lumi-Phos 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the concentration of prolactin in the sample. The amount of analyte in the sample is determined from a stored, multipoint calibration curve. Serial dilutions are prepared and analyzed, in addition to the neat sample, and results are evaluated for linearity. Non-linear results are forwarded to lab director for review and comment. (Assay manual: Beckman Coulter Inc. Fullerton CA, 2010)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 5 a.m.-5 p.m., Saturday; 6 a.m.-6 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Same day/1 day
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
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 Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|PRPM||Prolactin, Pituitary Macroadenoma||2842-3|