Determination of Reference Intervals for 10 Serum Proteins Measured by Rate Nephelometry, Taking into Consideration Different Sample Groups and Different Distribution Functions

Abstract

Summary: Reference intervals were established for 10 serum proteins (IgA, IgG, IgM, transferrin, haptoglobin, complement C3, complement C4, otj-acid-glycoprotein, <Xi-antitrypsin, <X2-macroglobulin) measured by rate nephelometry. The reference individuals -200 blood donors -were divided into 5 subgroups: men aged 19 -39 and 40 -60 years, women aged 19 -39 and 40 -60 years and women aged 19-48 years using oral contraceptives. Where possible, two or more subgroups were combined to give reference sample groups. Criteria for this procedure are given.The reference limits of the sample groups were estimated by parametric methods. Assuming that for a specified serum protein the type of distribution is the same in each subgroup, the data were standardized with estimated group specific parameter values and combined into one big sample. This permitted an improved determination of the underlying type of distribution. As a possible form of distribution we also considered the normal distribution truncated on the left side at c > 0. In some cases, after determination of an optimal c, this unusual distribution fitted the data significantly better than the generally used normal or log-normal distribution. Bestimmung von Referenzbereichen für 10 kinetisch nephelometrisch gemessene Serumproteine unter Berücksich-tigung verschiedener Stichprobengruppen und Verteilungsfunktionen

Circulating alpha1-antitrypsin in the general population: Determinants and association with lung function

“…Gender differences in AAT levels were even present in the situation of severe AAT deficiency although the results were not adjusted for hormone intake [23]. While previous reports on the association between use of oral contraceptives and AAT in the blood exist [24,25], our study extends this association to postmenopausal hormone intake. Our findings are compatible with an effect of estrogens or progesterone on hepatic AAT metabolism, which may be mediated by an inhibition of cytochrome P-450 activities [26].…”

Reference distributions for immunoglobulins A, G, and M: A comparison of a large cohort to the world's literature

“…A total of 109 publications were identified as containing immunoglobulin measurements on healthy individuals (9-117). Thirty-two studies reported only an arithmetic mean and insufficient data to estimate a reliable central estimate (13,18,(21)(22)(23)25,27,29,33,37,39,40,44,45,49,54,55,57,58,62,63,65,67,70,80,86,87,92,93,108,115,117). Twenty-two studies did not state a reference material and/or an assay method and were also excluded (11,12,14 1B).…”

Reference distributions for the positive acute phase proteins, ?1-acid glycoprotein (orosomucoid), ?1-antitrypsin, and haptoglobin: A comparison of a large cohort to the world?s literature

“…Five studies did not include the age of the study subjects (16,17,27,29,43), and two had multiple reasons for exclusion (15,33). The remaining 16 studies (4)(5)(6)13,14,19,21,23,24,(30)(31)(32)36,48,51,57) provided acceptable central estimates. Of these, 12 also provided acceptable reference ranges (4)(5)(6)19,21,24,(30)(31)(32)36,48,51).…”

“…A total of 27 publications were identified that contained information on α 1 -antitrypsin in apparently healthy individuals (4)(5)(6)8,11,13,17,18,(20)(21)(22)(23)(24)(25)(26)(37)(38)(39)(40)(41)45,49,(51)(52)(53)56,63). Four studies did not include adequate data on a reference material or an assay methodology (8,18,39,49).…”

“…Two studies did not include age (16,27), and one study had multiple reasons for exclusion (42). The remaining 12 studies (4)(5)(6)13,21,23,24,37,41,48,51,58) provided acceptable central estimates. Of these, eight studies provided acceptable reference ranges (5,6,21,24,37,41,51,58).…”