Chapter 6: Haemolytic Anaemias

Under physiological conditions, red cells maintain a lifespan of approximately 120 days before being removed by macrophages in the reticuloendothelial system. When destruction outpaces the bone marrow’s ability to compensate—even though the marrow can ramp up production to roughly six to eight times its normal rate—anaemia develops. The text categorizes these conditions into hereditary intrinsic defects and acquired extrinsic environmental factors. Clinical presentations often involve a triad of pallor, fluctuating jaundice, and an enlarged spleen, sometimes complicated by the development of pigment gallstones or aplastic crises triggered by viral infections like parvovirus. Laboratory diagnosis relies on identifying markers of increased cell turnover, such as elevated unconjugated bilirubin, absent serum haptoglobins, and significant reticulocytosis, alongside specific morphological clues on a blood film like microspherocytes or fragmented cells. Key hereditary conditions discussed include membrane protein deficiencies like hereditary spherocytosis and metabolic disorders such as glucose-6-phosphate dehydrogenase (G6PD) deficiency, which leaves cells susceptible to oxidant-induced damage from certain drugs or foods. Acquired causes are broadly split between immune-mediated types—where autoantibodies (warm or cold) or alloantibodies target red cells—and non-immune triggers including mechanical trauma from artificial heart valves, microangiopathic syndromes, and infections like malaria. Treatment is highly specific to the underlying cause, frequently involving the avoidance of triggers, pharmacological interventions like corticosteroids or monoclonal antibodies, and in some cases, surgical removal of the spleen to prolong red cell survival.