Full blood count and white cell differential count reference ranges obtained from a healthy urban South African population residing in the Western Cape of South Africa.

BACKGROUND: Research has suggested that individuals of African descent have lower white cell and neutrophil counts than Caucasians. These differences could lead to incorrect clinical decisions, and therefore, ethnic-specific reference ranges are required. The Western Cape region of South Africa is uniquely diverse, comprising Caucasian, Mixed Ancestry and those of African descent. The aim of this study was to compare the full blood count and differential counts across the three major ethnic groups residing in this area and to propose appropriate RIs. METHODS: The study formed part of the international project led by the Committee on Reference Intervals and Decision Limits (C-RIDL), and therefore, the strict guidelines laid out by the committee were followed. Full blood count and differential counts were performed on a Beckman Coulter ACT 5 diff AL analyser within 2-4 hours of collection and were reported as mean (standard deviation), 2.5th and 97.5th percentiles. Comparisons were analysed using Spss v25 and Statistica v13, and a P value of < 0.05 was considered significant. RESULTS: Reference ranges for Caucasian and Mixed Ancestry individuals were similar while white cell (P = 0.016), monocyte (P < 0.001), neutrophil (P = 0.034) and red cell indices were significantly different amongst the three population groups. There were however no statistical and clinical significant differences between the eosinophil, lymphocyte, red cell and platelet counts across the three groups. CONCLUSION: In conclusion, subjects of Mixed Ancestry, in this region, have similar reference intervals to those of European descent, while lower white cell and neutrophil counts in Africans have been confirmed.

A global multicenter study on reference values: 2. Exploration of sources of variation across the countries.

OBJECTIVES: The intent of this study, based on a global multicenter study of reference values (RVs) for serum analytes was to explore biological sources of variation (SVs) of the RVs among 12 countries around the world. METHODS: As described in the first part of this paper, RVs of 50 major serum analytes from 13,396 healthy individuals living in 12 countries were obtained. Analyzed in this study were 23 clinical chemistry analytes and 8 analytes measured by immunoturbidimetry. Multiple regression analysis was performed for each gender, country by country, analyte by analyte, by setting four major SVs (age, BMI, and levels of drinking and smoking) as a fixed set of explanatory variables. For analytes with skewed distributions, log-transformation was applied. The association of each source of variation with RVs was expressed as the partial correlation coefficient (rp). RESULTS: Obvious gender and age-related changes in the RVs were observed in many analytes, almost consistently between countries. Compilation of age-related variations of RVs after adjusting for between-country differences revealed peculiar patterns specific to each analyte. Judged fromthe rp, BMI related changes were observed for many nutritional and inflammatory markers in almost all countries. However, the slope of linear regression of BMI vs. RV differed greatly among countries for some analytes. Alcohol and smoking-related changes were observed less conspicuously in a limited number of analytes. CONCLUSION: The features of sex, age, alcohol, and smoking-related changes in RVs of the analytes were largely comparable worldwide. The finding of differences in BMI-related changes among countries in some analytes is quite relevant to understanding ethnic differences in susceptibility to nutritionally related diseases.

The iron status of a healthy South African adult population.

INTRODUCTION: Iron deficiency is associated with significant morbidity and mortality, can present with or without haematological changes and is a major cause of microcytic anaemia. In South Africa and Africa in general, there is a paucity of studies on the iron status of healthy adult non pregnant females and males >18years of age. The aim of the study was to determine the prevalence of iron deficiency in a healthy South African population. METHODS: A total of 651 healthy adults >18years were included in the study. Blood samples were taken for the determination of iron status, haematological and inflammatory parameters. A ferritin level of <30µg/L was used to define iron deficiency and these subjects were further divided into those with and without anaemia. Diet and menstrual history in females was further investigated. RESULTS: Overall, the prevalence of anaemia was 12.6% and iron deficiency was found in 78% of anaemic subjects. The prevalence of iron deficiency was 39.8% in all participants and females and Black Africans had a very high prevalence of 56.6% and 50.7% respectively. Significant (p<0.05) differences were found in concentrations of ferritin, haemoglobin, iron, transferrin, transferrin saturation, MCV and MCH between the groups. CONCLUSION: Anaemia is a minor health problem but a large proportion of subjects with iron deficiency do not present with anaemia. The prevalence of iron deficiency was high especially in females and Black African participants.

Comparison of LDL-cholesterol estimate using the Friedewald formula and the newly proposed de Cordova formula with a directly measured LDL-cholesterol in a healthy South African population.

BACKGROUND: The accurate determination of low density lipoprotein cholesterol (LDL-c) is pertinent in clinical practice. Most laboratories employ the Friedewald formula, for convenient estimation of LDL-c, despite its shortfalls. Different formulae have been proposed for use, for more accurate but convenient estimation of LDL-c. Here, we compare a new formula recently proposed by de Cordova et al., with that of Friedewald and LDL-c determined by a homogeneous assay. We also assess its performance at very low TG levels against the modified Friedewald formula recommended by Ahmadi et al. METHODS: A database of 587 adults from the 'Establishing Reference Intervals for Selected Analytes in South Africa' study was utilized. Fasting samples were assayed for lipids. LDL-c was determined by the Daiichi method. Performance of the Friedewald and the de Cordova formulae was compared. This was exclusively repeated at very low TG levels (<1.13 mmol/L), this time, including the Ahmadi formula. RESULTS: The Friedewald formula and the de Cordova formula both had high correlations with the direct LDL-c (r = 0.98 and r = 0.97, respectively), although the latter showed an inconsistent bias at different LDL-c levels. The two formulae had a higher correlation (r = 0.98) than the Ahmadi formula (r = 0.92) at very low TG levels. CONCLUSIONS: The Friedewald formula showed better agreement with the direct LDL-c than the de Cordova formula, at various LDL-c levels, in our population. It also performed better than the Ahmadi formula at very low TG levels. We therefore advise that it remains the formula of choice for LDL-c estimation in South Africa.

Penicillium Species Associated with Preharvest Wet Core Rot in South Africa and Their Pathogenicity on Apple.

Symptoms associated with the core region of apple fruits (Malus domestica) can be classified as moldy core (MC), wet core rot (WCR), and dry core rot (DCR). Infections leading to WCR are thought to occur primarily postharvest, although in South Africa preharvest symptoms also have been reported. The first aim of this study was to investigate the causative agent(s) of preharvest WCR by isolating fungi from eight internal positions in asymptomatic, MC, WCR, and DCR fruits. Secondly, the pathogenicity and virulence of all Penicillium isolates were investigated using three apple fruit inoculation methods: surface wounding, deep wounding, and nonwounding. Isolation of fungi from WCR fruits showed that Penicillium was the predominant fungal genus from most isolation positions including the lesion area. Penicillium ramulosum was the predominant species isolated from all fruits. However, in WCR fruits, the incidence (58%) of P. ramulosum was much higher than in MC (6%), DCR (7%), or asymptomatic (7%) fruits. Less frequently isolated Penicillium species included P. expansum and a few other species. Pathogenicity testing using the nonwounding method was best at discriminating highly virulent isolates. P. expansum was the most virulent species, followed by a putative new Penicillium species with closest sequence similarity to P. dendriticum. P. ramulosum isolates, although showing varying degrees of virulence, all had low virulence, causing only small lesions in wounded apple fruits.