Laboratory: Clinical Biochemistry  (HSC ONLY - AUTO)
Test Name:
Test Code: MPLH
Clinical Information:
Alternate Name(s): Monomeric prolactin
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.
Note: Stress during blood collection, many commonly used drugs (see more info below), including oral contraceptives, may cause hyperprolactinemia. Conditions such as kidney disease, primary hypothyroidism, adrenal insufficiency and PCOS have been implicated in increased levels of prolactin. Prolactin can be elevated in a number of physiological states: pregnancy, breast feeding, exercise, sleep, and foods high in proteins.
Macroprolactin investigation should only be requested on samples with elevated prolactin in asymptomatic patients.
Patient preparation instructions: Multivitamins (45–125 µg biotin) or biotin-only supplements up to 1 mg per day do not interfere with this test. Samples should not be taken from patients receiving therapy with high biotin doses (i.e. >5 mg/day) until at least 8 hours after the last dose.
Collection Devices:
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).
Specimen Stability: 
Ambient: 24 hours
Refrigerated: 7 days
Frozen:  3 months

Shipping & Storage: Store and ship frozen. Send two aliquot tubes (1.0 mL each).
Referred Out Location: Send specimen to Health Sciences Centre - MS5 for investigation by Clinical Biochemist
Reference Values:
Fraction of Macroprolactin Interpretation
<0.20 Normal
0.20 - 0.40 Borderline
>0.40 Abnormal

Approximately 0-40% of monomeric prolactin is coprecipitated with PEG.
Method of Analysis: Polyethylene glycol (PEG) precipitation pre-treatment, electrochemiluminescence immunoassay (Roche)
By Prior Arrangement Only
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).