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A practical method for the detection of macroprolactinaemia using ultrafiltration
Author(s) -
Prazeres Susana,
Santos M. Amparo,
Ferreira H. Gil,
Sobrinho Luís G.
Publication year - 2003
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1046/j.1365-2265.2003.01721.x
Subject(s) - ultrafiltration (renal) , peg ratio , chromatography , polyethylene glycol , chemistry , size exclusion chromatography , prolactin , medicine , endocrinology , biochemistry , hormone , finance , economics , enzyme
Summary objective The aim of this study was to evaluate a method for the estimation of the percentage of big‐big prolactin (bb‐PRL) in serum, based on centrifugal ultrafiltration (UF) and to be used for the detection of macroprolactinaemia. design Serum samples were submitted to gel filtration chromatography (GFC), UF and precipitation with polyethylene glycol (PEG). patients Serum samples obtained from 13 patients with macroprolactinaemia (Group 1) and from 15 hyperprolactinaemic patients without macroprolactinaemia (Group 2) were studied by the three methods. measurements PRL was measured in serum, fractions from GFC, filtrate and retentate obtained after UF (this last measurement was used only to study the ‘recovery’ of PRL after UF and was not necessary for clinical purposes), and supernatant obtained after PEG precipitation. The calculation of the percentage of bb‐PRL, by UF, was made using a simple algorithm. results In Group 1 the percentages (mean and SD) of bb‐PRL as determined by GFC, UF and PEG were, respectively, 73 ± 16, 83 ± 5·3 and 78 ± 7·0. In Group 2, the percentages of bb‐PRL were, in the same order as above, 4·3 ± 8·2, 16 ± 19 and 3·7 ± 11. The difference of the means between Groups 1 and 2 was highly significant ( P << 0·001) for all the three methods. In Group 1 the percentages of bb‐PRL were widely scattered when measured by GFC but closely clustered when measured by either UF or PEG. The opposite occurred in Group 2. conclusions The centrifugal ultrafiltration method for the detection of macroprolactinaemia is simple, inexpensive, requires only two prolactin assays and yields the same results as the polyethylene glycol precipitation method.