Internal Diseases and Therapy · MU Sofia

61. Hemolytic anemias. Hemolysis

Covers the definition of haemolytic anaemia and how to confirm it through four questions: increased breakdown, increased production, intra- versus extravascular site, and the underlying cause. It then walks through hereditary spherocytosis, elliptocytosis, G6PD and pyruvate kinase deficiencies, warm and cold autoimmune haemolytic anaemia with the Coombs test, and non-immune mechanical haemolysis. Includes a labelled blood-film picture of abnormal red cell shapes.

Inside: 1 section · 3 labelled pictures · 14 flashcards · 5 min

Topic 61 of 139 in the MU Sofia syllabus for Internal Diseases and Therapy (Medicine, Years 4 and 5). The free AceMed note covers it in 1 section, about 828 words (5 min of reading), with 14 flashcards.

In this note

  1. Hemolytic anemias. Hemolysis

Hemolytic anemias. Hemolysis

Haemolytic anemia is the premature breakdown of RBCs before their normal lifespan of 120 days. Hemolysis may be intravascular or extravascular (in the reticuloendothelial system i.e. macrophages of liver, spleen and bone marrow). The body will attempt to compensate for hemolytic anaemia with increased hematopoiesis, however if it is unable to do so then anaemia will occur.

To confirm hemolytic anemia, consider the following four questions:

  1. 1. Is there increased RBC breakdown
  2. a. Anaemia with normal or increased MCV
  3. b. Increase in unconjugated bilirubin
  4. c. Increase in urinary urobilinogen (excretion of unconjugated bilirubin)
  5. d. Increase in serum lactic dehydrogenase (LDH) as it is released from RBCs
  6. 2. Is there increased RBC production
  7. a. Increased reticulocyte number (reticulocytes = immature RBCs) - can cause increased MCV and polychromasia
  8. 3. Is haemolysis extra- or intravascular
  9. a. Intravascular features are:
  10. i. Marked increased free plasma haemoglobin (vs moderate increase)
  11. ii. Methaemalbuminaemia - broken down Hb allows haem to combine with albumin
  12. iii. Decreased plasma haptoglobin - is mopped up by free plasma Hb
  13. iv. Haemoglobinuria
  14. v. Hemosiderinuria
  15. b. Extravascular features are
  16. i. Splenic hypertrophy and splenomegaly
  17. 4. Finally ask, why is there hemolysis, some causes include
  18. a. Autoimmune
  19. b. Drug related
  20. c. Paroxysmal cold haemoglobinuria
  21. d. Microangiopathic haemolytic anaemia
  22. e. Infection
  23. f. Paroxysmal nocturnal haemoglobinuria
  24. g. G6PD deficiency
  25. h. Pyruvate kinase deficiency
  26. i. Hereditary spherocytosis
  27. j. Hereditary elliptocytosis
  28. k. Hereditary ovalocytosis
  29. l. Haemoglobinopathies (e.g. sickle cell, thalassaemia

So, now that we’ve done an overview of the haemolytic anemias in general, we need to consider some of the more important ones in a bit more detail. Strap in!

Red cell membrane defects - hereditary spherocytosis

AD, caused by structural proteins of RBC mutation. Most common inherited haemolytic anaemia (1 in 5000) .Affects alpha and beta spectrin, ankyrin, band 3 protein and protein 42 (creative naming!). These mutations lead to increased RBC fragility especially when passing through the spleen leading to extravascular haemolysis. Complications include haemolytic crisis (often with infection), megaloblastic crisis, aplastic crisis. Gallstones is also a common additional complication.

Diagnosis with peripheral blood film, treat with folate replacement and splenectomy where required (usually wait until age 6 for splenectomy).

Red cell membrane defects - hereditary elliptocytosis

Alpha-spectri and protein 41 defect. Also AD, although less common than spherocytosis.

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