Division of Haematology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, South Africa; National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa.
S Afr Med J. 2021 Mar 31;111(4):327-332. doi: 10.7196/SAMJ.2021.v111i4.15313.
Accurate laboratory reference intervals (RIs) are essential to differentiate between health and disease. There are variations in haematological indices within populations relating to gender, age, ethnicity and environment. Iron deficiency is common, has a wide range of clinical morbidities and affects red cell indices. Locally derived RIs for full blood count (FBC) parameters are needed for the Western Cape region of South Africa, after the exclusion of iron deficiency. In addition, information regarding the prevalence of iron deficiency in first-time blood donors would inform blood transfusion services regarding policies to screen for and treat iron deficiency.
To establish locally derived RIs for FBC and white blood cell (WBC) differential count parameters in healthy adults in the Cape Town area, by including first-time blood donors and excluding those with iron deficiency and thalassaemic indices. These new locally established RIs could update those in use by the local National Health Laboratory Service. A secondary objective was to establish the prevalence of iron deficiency in first-time blood donors. This would inform blood donation policies regarding screening and appropriate iron supplementation in high-risk groups prior to blood donation.
This was a prospective, descriptive study with direct convenience sampling. Participants were prospective voluntary blood donors aged between 18 and 60 years, presenting for first-time blood donation. Ethnicity was self-identified. Participants who tested positive for HIV or hepatitis B and/or C viruses were excluded. Prospective participants with iron deficiency, defined by serum ferritin levels below the RI, and those with red cell indices suggestive of an underlying thalassaemia trait were excluded. FBC samples were analysed using a Sysmex XN-1000 cell counter. Statistical non-parametric methods were used to calculate the RIs, according to international guidelines.
Of the 774 participants screened, 82 (11%) had iron deficiency and were excluded. Six hundred and sixty-two patients were included for analysis, 409 (62%) female and 253 (38%) male. The majority of the participants, 348 (53%), were between 20 and 29 years of age, with a mean age of 29 years for females and 28 years for males. Participants comprised a mix of the various ethnic groups residing in Western Cape Province. The mean haemoglobin concentration for females was lower than that for males (p<0.0001). There were significant gender differences for total WBC count, absolute neutrophil count and platelet count, with females having higher counts than males.
Locally established, population-specific RIs are essential for the accurate interpretation of haematological indices. This study established locally derived gender-specific RIs for the Cape Town region, after exclusion of iron deficiency. These new RIs have implications for the accurate diagnoses of cytopenias, cytoses and other blood count abnormalities. Iron deficiency is common in first-time blood donors, and screening for iron deficiency using point-of-care testing should be considered.
准确的实验室参考区间（RI）对于区分健康和疾病至关重要。在不同人群中，与性别、年龄、种族和环境有关的血液学指标存在差异。缺铁很常见，具有广泛的临床病态，并影响红细胞指标。在南非西开普省，需要为全血细胞计数（FBC）参数建立本地衍生的 RI，排除缺铁和地中海贫血指数。此外，首次献血者缺铁患病率的信息将为输血服务提供信息，以便制定针对缺铁的筛查和治疗政策。
通过纳入首次献血者并排除缺铁和地中海贫血指数，建立开普敦地区健康成年人的 FBC 和白细胞（WBC）分类计数参数的本地衍生 RI。这些新的本地建立的 RI 可以更新当地国家卫生实验室服务正在使用的 RI。次要目的是确定首次献血者缺铁的患病率。这将为献血政策提供信息，以便在高风险人群献血前进行筛查和适当的铁补充。
这是一项前瞻性描述性研究，采用直接便利抽样法。参与者为年龄在 18 至 60 岁之间、首次献血的志愿献血者。种族由参与者自行确定。排除 HIV 或乙型和/或丙型肝炎病毒检测呈阳性的参与者。排除血清铁蛋白水平低于 RI 的缺铁患者和提示潜在地中海贫血特征的红细胞指数患者。使用希森美康 XN-1000 细胞计数器分析 FBC 样本。根据国际指南，使用非参数统计方法计算 RI。
在筛选的 774 名参与者中，有 82 名（11%）患有缺铁症，被排除在外。662 名患者被纳入分析，其中 409 名（62%）为女性，253 名（38%）为男性。大多数参与者（53%）年龄在 20 至 29 岁之间，女性平均年龄为 29 岁，男性平均年龄为 28 岁。参与者来自西开普省的各种族群体。女性的平均血红蛋白浓度低于男性（p<0.0001）。总白细胞计数、绝对中性粒细胞计数和血小板计数存在显著的性别差异，女性的计数高于男性。
建立准确的人群特定 RI 对于准确解读血液学指标至关重要。本研究在排除缺铁症后，为开普敦地区建立了基于性别特异性的本地 RI。这些新的 RI 对准确诊断细胞减少症、细胞增多症和其他血液计数异常具有重要意义。缺铁症在首次献血者中很常见，应考虑使用即时检测进行缺铁症筛查。
