78993-3

LOINC code 78993-3 identifies "Prolactin isoforms panel - Serum or Plasma". The prolactin isoforms panel includes individual tests for monomeric, dimeric, and macroprolactin, as well as fraction terms for each isomer and an interpretation based on all of the results. Monomeric prolactin is the most common form of circulating prolactin. The dimeric form ("big-prolactin") has a molecular weight of ~50 kD, and polymeric form ("big-big prolactin") has a molecular weight of ~ 150 kD). Big-big prolactin, known as macroprolactin, and big prolactin are formed in the circulation after secretion of prolactin from the pituitary. They have a longer half-life than monomeric prolactin and are not biologically active. However, typical prolactin assays do not differentiate between the different forms of prolactin, and the presence of big and big-big prolactin can lead to a false diagnosis of hyperprolactinemia. Methods such as PEG precipitation can separate macroprolactin and big prolactin from monomeric prolactin in order to obtain a more accurate measurement of biologically active prolactin, and chromatography can be used to further characterize the isoforms if necessary. [PMCID: PMC3719302]

This code measures Prolactin isoforms panel in Ser/Plas. It belongs to the PANEL.CHEM class in the LOINC classification.

LOINC (Logical Observation Identifiers Names and Codes) is a universal standard for identifying laboratory and clinical observations. It is maintained by the Regenstrief Institute and used worldwide for health data exchange.