Paediatrics: Deficiency anaemias

Deficiency anaemias

Iron deficiency

Commonest nutritional deficiency. Occurs in 10–30% of those at high risk:

·  Preterm, LBW infants, multiple births;

·  After exclusive breastfeeding >6mths, delayed introduction of iron-containing solids, excessive cow’s milk (protein enteropathy);

·  Adolescent females (growth spurt and menstruation);

·  Low iron-containing diet due to poverty, fad diets, or strict vegans.

Causes

·  Dietary: commonest cause, e.g. prolonged and exclusive consumption of cow’s or breast milk with late introduction of iron containing solids.

·  Infancy and early childhood: low level of dietary iron, e.g. high milk intake (low iron), GI blood loss, e.g. cow’s milk protein enteropathy.

·  i Demand due to rapid growth: e.g. following prematurity or puberty.

·  Malabsorption: e.g. coeliac disease, IBD.

·  Rarely blood loss: e.g. Meckel’s diverticulum, oesophagitis. Bleeding may be occult into cysts, tumours or s to drugs, e.g. NSAIDs.

·  Intestinal parasites: e.g. hookworm (in less developed world).

Presentation

·  Most cases are subclinical. Onset of symptoms of anaemia is usually insidious. Profoundly iron deficient toddlers usually adapt to their anaemia and tolerate surprisingly low Hbs.

·  Pallor, lethargy, poor feeding, breathlessness (only in severe anaemia).

·  May also develop symptoms associated with iron deficiency, including neurological effects of listlessness and irritability (infants), mood changes, reduced cognitive and psychomotor performance (can occur at levels of mild/moderate deficiency before anaemia develops), and rarely, pica (eating unusual items, e.g. soil, chewing on pencils).

Diagnosis 

Iron deficiency anaemia is a sign not a diagnosis—always look for underlying cause (usually dietary or GI disease).

·  FBC: Hb d, MCV & MCH & MCHC ‘fall’ (below normal range for age), platelets often raised.

·  Blood film: microcytic, hypochromic anaemia.

·  Serum ferritin ‘fall’ (indicative of iron stores): it may be low before anaemia. Check C-reactive protein, as ferritin may be falsely raised due to acute phase reaction (d serum iron and ‘rise’total iron binding capacity (TIBC) confirms iron deficiency).

Treatment 

Give 5mg/kg elemental iron/day (as oral ferrous salt) given in 2–3 divided doses (max dose of 200mg/day). Response in reticulocyte count is usually within 5–10 days. Continue for 3mths after Hb normalizes to replenish body stores. If indices don’t improve once Hb normalized, screen for thalassaemia trait.

Prevention in high risk groups

Iron supplementation in preterm infants.

·Encourage iron-containing diet, e.g. iron fortified formulas and breakfast cereals, meat, green vegetables, beans, egg yolk, foods rich in vitamin C (i iron absorption).

·Avoid prolonged cow’s milk consumption to detriment of solids intake.

Macrocytic anaemia

Vitamin B₁₂ deficiency 

Vitamin B₁₂ (cobalamin) usually sourced from animal products. Vegan or other diets lacking meat most at risk. Alternatively, can have defective absorption due to intrinsic factor deficiency (congenital autosomal recessive (AR) or juvenile autoimmune pernicious anaemia), defective B₁₂ transport (transcobalamin II deficiency), intestinal disease causing malabsorption (ileal resection, IBD, coeliac disease), or bacterial over-growth in small bowel.

Folate deficiency

A common nutritional deficiency worldwide. Causes include:

·Malnutrition (marasmus, kwashiorkor), goat’s milk feeding.

·Malabsorption, e.g. coeliac disease, IBD, other small intestinal disease;

·Increased requirements, e.g. rapid growth, chronic haemolytic anaemias (give daily folic acid prophylactically), hypermetabolic states (infection, hyperthyroidism), severe skin disease.

·Drugs, e.g. phenytoin, valproate, trimethoprim, nitrofurantoin.

·Disorders of folate metabolism: Lesch–Nyhan syndrome; orotic aciduria.

Presentation for folate or vitamin B₁₂ deficiency

·Insidious onset of pallor, fatigue, anorexia, glossitis, developmental delay, and hypotonia.

·In severe cases, subacute combined degeneration of cord (rare in children): paraesthesia of hands/feet, ataxic gait, loss of vibration sense.

Diagnosis of macrocytic anaemias

·Macrocytic anaemia: Hb d, MCV ‘rise’(above the normal range for age, i.e. >82 aged 1yr, >90 aged 6–12yrs or >125fL as a newborn).

·WBC d, hypersegmented neutrophils, platelets d, bilirubin i.

·d Serum B₁₂ or ‘fall’ folate level (red cell folate level is more reliable than serum folate, which reflects recent intake).

·Bone marrow, if indicated, shows megaloblastic appearance.

·Rarely, intrinsic factor autoantibodies or test of B₁₂ absorption, e.g. Schilling test.

Treatment

Improve diet. Depending on whether vitamin B₁₂ or folic acid is deficient:

·B₁₂ deficiency: IM hydroxocobalamin (1mg)—usually response is within 1wk. Watch K⁺ level as it may drop. Treat 3 times/wk until Hb normal; then give 2–3-monthly if the underlying problem persists (important to identify cause).

·Folate deficiency: daily oral folic acid (500micrograms/kg). Response is prompt (within few days).

·  look for underlying cause (usually GI).

·  never treat with folic acid alone unless serum B12 level is known to be normal, as subacute combined degeneration of the cord can be precipitated.