Clinical features

Congenital infections: all rare with adequate antenatal care. Most infants with herpes simplex will be symptomatic with DIC and hepatic dysfunction—haemolysis is not a major finding. Haemolytic anaemia is also mild in CMV and rubella infections but 50% infants with toxoplasmosis will be anaemic (may be severe).

Post-natal infections: viral, bacterial and protozoal (congenital malaria can be delayed for some days or weeks or it can be acquired early in life). Anaemia can be severe and associated with DIC.

MAHA 2° to toxic damage to the endothelium is rare in the neonate outside the context of DIC and sepsis, and is seen in burns and (classically) in the Kasabach-Merritt syndrome—a visible or covert giant haemangioma with haemolysis, RBC damage and profound thrombocytopenia.

Drugs/chemical exposure are more likely to cause Heinz body haemolysis in premature babies or those with G6PD deficiency. Incriminating agents include sulphonamides, chloramphenicol, mothballs, aniline dyes, maternal intake of diuretics and, in the past, water-soluble vitamin K analogues. Vitamin E (a potent antioxidant) has a number of RBC stabilising activities. Now rare due to dietary supplements, deficiency used to be seen occasionally in premature infants, following oxygen therapy and diets rich in polyunsaturated fatty acids. Clinical findings included haemolysis, pre-tibial oedema and CNS signs. Acanthocytosis/pyknocytosis of the RBC is characteristic, and this may have been the main cause of infantile pyknocytosis.

Infantile pyknocytosis: indicates the diagnostic feature of this uncommon acquired disorder. Haemolysis with increased numbers (>6-50%) of pyknocytes (irregularly contracted RBCs with multiple projections) in the peripheral blood. Cause unknown, though may be associated with vitamin E deficiency. Anaemia may be severe and present at birth, and is most striking at ~3 weeks (Hb <5g/dL reported). Exchange transfusion occasionally required but the condition spontaneously remits by ~3 months. Its self-limiting nature and ill-understood pathology means that it may not be a distinct clinical entity.

Metabolic disorders—rare. Laboratory investigation

Criteria set out above will establish the diagnosis of haemolytic anaemia. A +ve DAT points to an immune process—probably Rh/ABO disease. If non-immune, further tests to look for a congenital abnormality.

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