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Macroprolactin Investigations

Category Biochemistry >> Endocrinology
Test background

Macroprolactinaemia refers to a polymeric form of prolactin in which several molecules form aggregates with circulating IgG. This rarely elicits a biological response due to the inability of such a large molecule to interact with the prolactin receptor, however, it can be detected by immunoassays leading to spurious elevated prolactin results. Macroprolactin investigations use a PEG precipitation procedure to remove macroprolactin so that the remaining bioactive monomeric form of prolactin can be estimated.

Clinical Indications

Differential diagnosis of macroprolactin-associated hyperprolactinaemia with that of prolactinoma, hypothyroidism or drug/stress-induced hyperprolactinaemia. For samples assayed for total prolactin within NWLP laboratories macroprolactin investigations are automatically added for male patients with total prolactin >450 mU/L and female >600 mU/L.

Reference range

Monomeric prolactin reference range:

Male <310 mU/L

Female <420 mU/L

Sample & container required SST (gold top) or serum (red top)
Sample volume 0.5 mL
Transport storage Stable for 7 days at 2-8°C. Samples can be sent by first class post.
Turnaround time 10 days