Doctoral Degrees (Chemical Pathology)

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Browsing Doctoral Degrees (Chemical Pathology) by Author "Omuse, Geoffrey Amuka"

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    Reference intervals for common chemistry and haematology laboratory tests in a healthy Kenyan population: variation with age, sex, BMI and comparison with a South African
    (2020-12) Omuse, Geoffrey Amuka; Erasmus, Rajiv; Ichihara, Kiyoshi; Premji, Zulfiqarali; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology. Chemical Pathology.
    ENGLISH ABSTRACT: Introduction Laboratory results play an important role in assessment of one’s health status including detection of sub-clinical disease. Reference intervals (RIs) have been shown to vary across different populations due to various reasons including ethnic and racial differences, differences in reference populations and statistical approaches used in deriving the RIs. The International Federation of Clinical Chemistry committee on reference intervals and decision limits has been carrying out a global study aimed at harmonizing RIs. Kenya is the only country in East Africa that participated in this study and therefore the derived RIs will serve as a reference point for laboratories in the region. It is also important to identify what factors cause variations in RIs and whether partitioning based on age or sex will make them more specific. We subsequently compared our RIs with those from South Africa also derived as part of the global RI study. Methods Recruitment of study participants in Kenya was carried out between January and October 2015 in several counties after obtaining informed consent. Inclusion of participants was limited to healthy adults aged 18-65 years stratified into 4 age groups: 18-29, 30-39, 40-49 and 50-65 years. Haematology tests were performed at the PathCare laboratories in Nairobi, Kenya while all other analysis was done at the PathCare reference laboratory in Cape Town, South Africa. For purposes of the global RI study, all participating laboratories received a panel of sera that had assigned values to enable recalibration of reference values (RVs) and alignment across different countries. RIs were determined using both parametric and non-parametric methods before and after applying the latent abnormal values exclusion (LAVE) method. Results Out of 596 volunteers, 533 met the inclusion criteria: 260 (48.8%) males and 273 (51.2%) females. The prevalence of metabolic syndrome (MetS) was 25.6% and less than 1% of participants had reduced estimated glomerular filtration rate (eGFR). Sex-specific RIs were required for uric acid, creatinine, total bilirubin (TBil), total cholesterol (TC), transaminases, transferrin, transferrin saturation and immunoglobulin-M. Age-specific RIs were required for glucose and triglyceride for both sexes, and for urea, magnesium (Mg), TC, HDL-cholesterol ratio, alkaline phosphatase (ALP), and ferritin for females. Kenyan RIs were comparable to those of other countries participating in the global study with a few exceptions such as higher ULs for TBil and c-reactive protein (CRP). South African RIs for uric acid, TC, low density lipoptotein cholesterol, alanine transaminase, lactate dehydrogenase, ALP, albumin, Mg, thyroid stimulating hormone and prostate specific antigen were lower than the Kenyan RIs. Conclusion Kenyan RIs for several analytes were established using a harmonized protocol from well-defined reference individuals. Given the rigour with which the study was conducted, the derived RIs will provide a useful reference for laboratories in sub-Saharan Africa that are looking for RIs for common haematology and biochemistry tests. For most analytes, harmonization of RIs between Kenyans and South Africans of African ancestry was not possible as they could result in misclassification of individuals as either diseased or healthy given the differences seen.