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Macroprolactin

Source Blood
Mnemonic CMISC
Specimen Requirements

1 x 3 mL or 4.5 mL light green (mint) top PST tube. Gold top SST tube also acceptable.

0.5 mL plasma or serum

Specimen Handling
Additional Information

Hyperprolactinemia may be caused by the presence of a high molecular mass complex of prolactin called macroprolactin. In this situation, the patient is asymptomatic. Hyperprolactinemia attributable to macroprolactin is a frequent cause of misdiagnosis and mismanagement of patients. Macroprolactinemia should be considered if, in the presence of elevated prolactin levels, signs and symptoms of hyperprolactinemia are absent.

Prolactin is measured before and after Polyethylene Glycol precipitation of macroprolactin. Results are expressed as % recovery after this precipitation.
Testing Location Chemistry-DSC
Testing Frequency Daily
Alternate Name(s)
Reference Interval

<= 40% recovery is indicative of macroprolactin
>= 60% recovery is indicative of absence of macroprolactin
40 – 60% recovery indicates a grey zone