| Laboratory: | Clinical Biochemistry (SPECIAL CHEMISTRY) | ||||||||||||||||||||||||
| Test Name: |
MACROPROLACTIN - (S)
Test Code:
MPLH
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| Clinical Information: |
Description: Macroprolactin investigations using PEG precipitation include reporting of:
1) Prolactin, Total 2) Prolactin Monomeric – Unprecipitated (measured post-PEG treatment) Macroprolactin – Precipitated (calculated percent) Test Indications: Current Prolactin method is very specific for biologically active monomeric prolactin and macroprolactin investigations are rarely required. Contact Clinical Biochemist to discuss the need for investigations. |
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| Collection Devices: |
Preferred Device:
Acceptable specimen include serum with or without gel
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| Specimen Required: |
Serum: 1.0 mL
Collection Information: Preferred sample collection is 3-4 hours after waking (e.g. physiological peak), but any time of collection is acceptable. Avoid stress during blood collection. Special Processing: Aliquot serum into two tubes (1.0 mL each). One aliquot to be sent to HSC Automated chemistry for prolactin measurements and the second aliquot to be sent to HSC Special Chemistry (MS5) for MPL testing. Specimen Stability: Ambient: 24 hours Refrigerated: 7 days Frozen: 3 months |
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| Referral: |
Shipping & Storage: Store and ship frozen. Send two aliquot tubes (1.0 mL each).
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| Requisition: | |||||||||||||||||||||||||
| Reference Values: |
Prolactin, Total
a Recommended reference interval in patients taking ethinyl estradiol contraceptives is 5-52 µg/L. Prolactin Monomeric, Unprecipitated
Macroprolactin, Precipitated: Greater than 40% of serum prolactin precipitated following incubation with polyethylene glycol (PEG) suggestive of the presence of macroprolactin. Note that elevated monomeric prolactin, even in the presence of macroprolactin, is consistent with hyperprolactinemia. These results should be interpreted in the context of patient presentation and other clinical findings. Monomeric Prolactin (Unprecipitated): Serum treated with 25% aqueous PEG solution to precipitate macro-complexes. Post-centrifugation prolactin is measured using Roche assay. Macroprolactin (precipitated) is calculated by subtracting unprecipitated prolactin from total prolactin and reported as percentage to total prolactin.
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| Availability: |
Within 2 Weeks
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| See Also: | |||||||||||||||||||||||||
| More Information: |
Interpretation & Assay Interferences: Presence of macroprolactin does not exclude possibility of pituitary adenoma. Results should be interpreted in the context of clinical findings.
Drugs and medications are the most common cause of non-tumoral hyperprolactinemia. For example, oral contraceptive pill, anesthetics, antihypertensives, antihistamines (H2), anticonvulsants, antidepressants, cholinergic agonists, dopamine receptor blockers, dopamine synthesis inhibitors, etc. The neuroleptics and anti-psychotic drugs can also cause hyperprolactinemia (e.g. 50-100% of patients on respiradone). |
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