March 15, 2013

Hyperprolactinemia and Macroprolactinemia

Hyperprolactinemia due to big big prolactin is differently detected by commercially available immunoassays.
-B Cavaco, S Prazeres, et al.
J Endocrinol Invest. 1999 Mar;22(3):203-8.

"Macroprolactinemia, i.e. sustained hyperprolactinemia where the predominant circulating form of prolactin (PRL) is of large molecular weight, is a common phenomenon comprising up to one-fourth of all cases of hyperprolactinemia."

"we suggest that the routine measurement of PRL should be done with methods that are only minimally affected by the presence of macroprolactin."

Hyperprolactinemia or pseudohyperprolactinemia?

Reporting of Post–PEG Prolactin Concentrations: Time to Change
-T Smith, M Fahie-Wilson
Clinical Chemistry March 2010 vol. 56 no. 3 484-485

Measurement of serum prolactin levels can be exagerated by the presence of biologically inactive "big prolactin" or "macroprolactin", aka "big big prolactin".

"The polyethylene glycol (PEG) precipitation test is widely used to detect pseudohyperprolactinemia caused by big prolactin and/or macroprolactin. Current best practice recommends that all sera with increased total prolactin concentrations be subfractionated by PEG precipitation to measure the bioactive monomeric prolactin concentration, a more clinically meaningful variable."