ANAEMIA

Conditions characterised by inadequate blood haemoglobin (Hb) levels. It is quite common in tropical settings, and often  caused by multiple factors. Children and young women are particularly at risk.

Normal haemoglobin levels by age

CATEGORY NORMAL
VALUE
MILD
ANAEMIA
MODERATE
ANAEMIA
SEVERE
ANAEMIA
Men >15
years
>13 g/dL 11-12.9 g/
dL
8-10.9 g/
dL
<8 g/dL
Women >12 g/dL 11-11.9 g/
dL
8-10.9 g/
dL
<8 g/dL
Pregnant
women
>11 g/dL 10-10.9 g/
dL
7-9.9 g/dL <7 g/dL
Child 12-
14 years
>12 g/dL 11-11.9 g/
dL
8-10.9 g/
dL
< 8 g/dL
Child
5–11
years
>11.5 g/
dL
11-11.5 g/
dL
8-10.9 g/
dL
<8 g/dL
Child 6
months–
5 years
>11 g/dL 10-10.9 g/
dL
7-9.9 g/dL <7 g/dL

From WHO/NMH/NHD/MNM/11.1

Reference range in newborns and infants

AGE NORMAL RANGE
Birth >13.5 g/dL
2 weeks >12.5 g/dL
1-6 months > 9.5 g/dL

Adapted from Medscape Sept 2016 haemoglobin concentration

Causes

Decreased production of red blood cells

  • Nutritional iron, and/or folic acid/vitamin B12 deficiency
  • Depressed bone marrow function (leukaemia, aplasia)
  • Infections (HIV, TB, visceral leishmaniasis)

Increased destruction of red blood cells (haemolysis)

  • Malaria
  • Drug side effects (dapsone, cotrimoxazole, AZT)
  • Congenital disorder, e.g. sickle cell anaemia

Loss of red blood cells

  • Acute and chronic blood loss (e.g. haemorrhage after trauma, hookworm infestation, pregnancy, abortion, heavy menstrual loss, schistosomiasis, massive or chronic GI bleeding)

Clinical features

Commonly

  • Pallor of conjuctivae, mucous membranes, palms, soles
  • Fatigue, dizziness, palpitations, headache, anorexia, sometimes weight loss, low exercise tolerance
  • Signs of heart failure if severe: oedema in lower limbs, dyspnoea, tachycardia, heart murmurs
  • If due to acute blood loss: postural hypotension, decreased cardiac out put, tachycardia, sweating, restlessness and thirst
  • Look for signs of specific pathology, e.g., splenomegaly, malaria, nutrition deficiency, haemolytic jaundice, etc.

Investigations

  • Complete blood count (CBC) with differentials, Mean Corpuscolar Volume (MCV), platelets, and a peripheral
    smear
  • Evaluate Hb levels according to the patient’s age
  • Classify anaemia according to MCV
    • Microcytic (small RBCs): usually iron deficiency, thalassemias, sideroblastic anaemia
    • Macrocytic: vitamin B12 or folate deficiency, thyroid disease, chronic alcohol abuse, antifolate medications
    • Normocytic: acute loss, renal failure, bone marrow infiltration or suppression, chronic disease, haemolytic anaemias
  • Other tests according to suspected cause: reticulocyte count, screen for sickle cell, stool for ova, parasites and
    occult blood, and blood slide/RDT for malaria parasites
Note
  • Anaemia is not a final diagnosis: careful history, physical examination and laboratory tests are essential to
    determine the cause

Management

General principles

  • Determine and treat the cause
  • Consider need of blood transfusion according to:
    • Level of haemoglobin
    • Clinical condition (haemodynamic status of patient, presence of heart failure, ongoing blood loss)