By Dr Jasmine Ramiah — Clinical Haematology
The blood count that counts.
Introduction: The South African Reality
Anaemia is one of the most common presentations encountered in South African clinical practice. National statistics postulate that approximately one-third of women of reproductive age and up to 40% of young children experience anaemia. South Africa has an estimated 7.8 million people living with HIV and remains among the highest tuberculosis (TB) burden countries globally. The prevalence of anaemia in people living with HIV ranges between 20% and 60% depending on the stage of disease whilst more severe anaemia is noted in active TB. It is well documented that the presence of anaemia adversely impacts on prognostication, morbidity and mortality in both diseases.
The aetiology of anaemia is multifactorial and may be related to infection, chronic inflammation, nutritional deficiency, renal dysfunction, medication toxicity profiles, and marrow suppression often coexist.
In honour of World Anaemia Awareness Day on the 13th of February, this article aims to increase awareness whilst providing a structured, pragmatic approach, essential in frontline care.
Step 1: Classification by MCV — A Practical Framework
Microcytic anaemia (MCV <80 fL) most commonly reflects iron deficiency or anaemia of chronic inflammation and in rare instances an inherited haemoglobinopathy. The cause of iron deficiency includes pregnancy, menorrhagia, gastrointestinal blood loss, parasitic infection, dietary or nutritional host factors. Inflammation- mediated iron sequestration is highly prevalence in chronic illnesses such as TB and HIV.
Normocytic anaemia (MCV 80–100 fL) is frequently associated with chronic disease, renal impairment, early iron deficiency, haemolysis, acute blood loss, TB, advanced HIV, opportunistic infections, lymphoma, and antiretroviral toxicity.
Macrocytic anaemia (MCV >100 fL) should prompt evaluation for substrate deficiencies such as vitamin B12 or folate deficiency, liver disease, hypothyroidism, alcohol use, medication effects, and bone marrow pathology such as myelodysplastic syndrome (MDS).
Step 2: Distinguish Iron Deficiency from Inflammation
Iron deficiency represents true depletion of iron stores and impaired haemoglobin synthesis. The iron stores are most accurately reflected on a bone marrow aspirate biopsy suing a Perls Stain to grade the iron stores, this is regarded as the gold standard of testing as serum iron studies are labile and subject to analytical variables. Anaemia of inflammation is pathological driver by cytokine-mediated hepcidin elevation, which reduces intestinal iron absorption and traps iron within macrophages by blocking the release of iron through ferroportin at the baso-lateral membrane of the gastro-intestine.
Ferritin is the most useful initial serum marker but is also an acute phase reactant therefore highly labile. Ferritin <30 µg/L strongly suggests iron deficiency. In inflammatory states, ferritin <100 µg/L may still indicate deficiency. The transferrin saturation is a useful parameter in addition to the serum ferritin which is <20% supports iron deficiency. Low serum iron with low transferrin and normal or elevated ferritin suggests an anaemia of inflammation and underlying chronic illness should be investigated for such as HIV and or TB coupled with judicious utility of inflammatory markers as substantiating evidence.
Step 3: Apply Judicious Transfusion Thresholds
As a golden rule, the decision to transfuse should always be a clinical one rather than based didactically on numerical values. In a haemodynamically stable, non-bleeding adults, transfusion is generally considered when haemoglobin falls below 7 g/dL. Once again the clinical comorbidities influence management for example in patients with cardiovascular disease or significant symptoms, a threshold around 8 g/dL may be more appropriate. Urgent transfusion is indicated in haemodynamic instability note by clinical manifestations such as chest pain, syncope, or severe dyspnoea.
Step 4: Recognise Referral Triggers
Urgent referral or consultation with a haematologist is warranted for haemoglobin <6 g/dL, pancytopenia, suspected haemolysis, abnormal blood film suggestive of malignancy, persistent unexplained macrocytosis, transfusion dependency, or failure to respond to appropriate iron therapy.
Clinical Pearls
- In high HIV/TB settings, anaemia is often multifactorial, it is therefore recommended that one treats infection and deficiency concurrently.
- The serum ferritin value can be falsely reassuring in inflammatory states, therefore interpretation in conjunction with inflammatory markers and transferrin saturation may provide assistance.
- The reticulocyte count may provide diagnostic clues for example; a low reticulocyte count suggests underproduction; a high count suggests haemolysis or blood loss.
- Do not transfuse numbers, transfuse symptomatic or haemodynamically unstable patients.
- Failure to respond to iron within 2–4 weeks requires reassessment in conjunction with a haematologist.
- Severe anaemia in TB or advanced HIV is a prognostic red flag requiring urgent evaluation.
Conclusion: Treat the Cause, Not Just the Count
The prevalence of anaemia in South Africa’s high HIV/TB environment is increasingly common, complex, and prognostically significant bearing adversely on morbidity and mortality. A structured MCV-guided framework, coupled with a detailed clinical evaluation and ancillary investigations such as iron studies, rational transfusion practice, and clear referral thresholds enable safe and effective management in resource-limited settings. Addressing anaemia is not merely correction of numbers but rather is central to improving survival and strengthening health systems.