Gestational age-specific reference intervals for 15 biochemical measurands during normal pregnancy in China

Abstract

Aims Physiological changes that occur during pregnancy can influence biochemical parameters. Therefore, using reference intervals based on specimens from non-pregnant women to interpret laboratory results during pregnancy may be inappropriate. This study aimed to establish the essential reference intervals for a range of analytes during pregnancy. Methods A cross-sectional study was performed in 13,656 healthy pregnant and 2634 non-pregnant women. Fifteen biochemical measurands relating to renal and hepatic function were analysed using an Olympus AU5400 analyzer (Olympus, Tokyo, Japan). All the laboratory results were checked for outliers using Dixon's test. Reference intervals were established using a non-parametric method. Results Alanine aminotransferase, aspartate aminotransferase, albumin, cholinesterase, creatinine, direct bilirubin, gamma-glutamyl transpeptidase, total bilirubin, total bile acid and total protein showed a decrease during the whole gestational period, while alkaline phosphatase and uric acid increased. Urea nitrogen, β-microglobulin and cystatin-C fell significantly during the first trimester and then remained relatively stable until third trimester. Reference intervals of all the measurands during normal pregnancy have been established. Conclusions The reference intervals established here can be adopted in other clinical laboratories after appropriate validation. We verified the importance, for some measurands, of partitioning by gestational age when establishing reference intervals during pregnancy.

New trimester-specific reference intervals for clinical biochemical tests in Taiwanese pregnant women-cohort of TMICS

“…We also compared our RIs for other biochemical parameters with those reported by other studies. Several relevant studies have recently provided RIs for clinical biochemical parameters in pregnant women in China [4,5,12]. Two of those studies found pregnant women in their third trimester had lower Cr compared to non-pregnant women [4,12], similar to our findings.…”

“…There has been no agreement on the effect of pregnancy on serum AST and ALT. Some studies, like ours, report a slight increase in AST and/or ALT levels in the third trimester [26,27], while other studies found slight decreases [4,12], the differences possibly due to racial make up of the populations they studied, underlying liver diseases, or other factors. Some studies of a Chinese population report RBC, Hb, HCT, MCHC, lymphocyte count, and PLT to be lower and WBC and neutrophil counts to be higher in pregnant women [4,5], as we have.…”

“…Most tables of reference intervals for pregnant women focus on thyroid hormones [1][2][3], followed by blood routine [4,5] as well as others including pregnancy associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin, tumor necrosis factor-α (TNF-α) and interferon gamma (INF-γ) [6,7]. There are some sources that provide reference ranges or laboratory values for pregnant women in western countries [8][9][10][11] and there are several papers that provided them for pregnant women in some Asian populations [3][4][5]12]. There are none in Taiwan.…”

Breast cancer risk and serum levels of per- and poly-fluoroalkyl substances: a case-control study nested in the California Teachers Study

“…This poses some complication in the interpretation of the study’s results. Pregnancy-related changes in blood volume and alterations in concentrations of serum albumin [ 70 ] to which PFASs bind, may affect PFAS serum levels. Analyses of NHANEs data have suggested lower PFOS levels in pregnant women [ 71 ].…”

Early pregnancy reference intervals; 29 serum analytes from 4 to 12 weeks’ gestation in naturally conceived and uncomplicated pregnancies resulting in live births

“…Unfortunately, most RIs for pregnant women are available from the late first or early second trimester and onwards [8][9][10][12][13][14] or are extrapolated from a control group of participants in a trial examining a first trimester complication [10]. Accordingly, such values are not ideal for identifying early pregnancy abnormalities and often lack the statistical requirements recommended for establishing RIs by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) [15].…”