Reference Intervals for Serum Biochemistry Analytes for Pregnant Mothers of Taita-Taveta County, Kenya

Reference intervals for pregnant women for blood analytes which are known to change with the trimester of pregnancy are rare. Most clinical laboratories in Africa including Kenya use reference intervals for non-pregnant women developed using western populations to interpret laboratory results for pregnant women which is inappropriate; important pathological changes may be missed, and normal changes may be interpreted as pathological conditions. The aim of this study was to develop trimester specific reference intervals for fifteen serum biochemistry analytes for pregnant women of Taita-Taveta County, Kenya. This was a cross-sectional study involving 296 healthy pregnant women randomly recruited in their second and third trimester attending Moi Subcounty Hospital antenatal clinics from the 16th week after meeting the inclusion criteria, between May 2015 and December 2017. Five millilitres of venous blood was drawn from each participant into plain vacutainer tubes, allowed to clot and then centrifuged to obtain serum. The levels of the serum biochemistry analytes were measured using Clinical Chemistry Autoanalyzer (Integra 400) and reported using SI units. Reference intervals spanning the 2.5 and 97.5 percentiles of each of these analytes were calculated using Clinical Laboratory Standards Institute (CLSI, 2010) guidelines on the obtained non-parametric dataset. Trimester independent reference intervals for total protein, albumin, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, blood urea nitrogen, potassium, chloride, and calcium were established. Trimester dependent reference intervals for alkaline phosphatase, total bilirubin, direct bilirubin, creatinine, uric acid, and sodium were established. In conclusion, trimester specific reference intervals were developed for serum biochemistry analytes for pregnant women of Taita-Taveta County, Kenya different from those reported in literature. These developed reference intervals can be adopted for accurate diagnosis of pathological conditions during pregnancy for this population.