A 20 years old female presenting with anemia, mild jaundice for 2 years, peripheral smear showing spherocytes, the best investigation to be done is:
Answer is C (Coomb's test) Presence of anemia and jaundice together with spherocytes. in peripheral smear is consistent with a diagnosis of both hereditary spherocytosis and auto immune hemolytic anemias. The onset of symptoms at 40 years of age ours an acquired etiology and suggests a presumptive diagnosis of Acquired Autoimmune Hemolytic anemias. Neveheless, mild cases of Hereditary spherocytosis may also first present in young adults and even later in life (Harrison) Coomb's test is the single best investigation for such patients as it can clinch the diagnosis of Autoimmune Hemolytic anemias and establish the distinction between the two probable diagnosis. According to Harrison text: `Hereditary spherocytosis must be distinguished primarily from the spherocytic hemolytic anemias associated with RBC antibodies' Coomb's test is positive in immune spherocytic hemolytic anemias and it is negative in hereditary spherocytosis "The diagnosis of immune spherocytosis is readily established by a positive coomb's test" - Harrison "Coomb's test is negative in hereditary spherocytosis" CMDT 06 Osmotic fragility test will be positive in both hereditary spherocytosis and immune spherocytic hemolytic anemias. "Increased osmotic fragility merely reflects the presence of spherocytes and does not distinguish hereditary spherocytosis from other spherocytic hemolytic disorders such as autoimmune hemolytic anemia" - CMDT 06/491 Coomb's test is the single best next investigation here as it will establish the distinction. Note: Presence of spherocytes in the peripheral blood smear does not necessarily imply hereditary spherocytosis Causes of spherocytosis in peripheral smear / Spherocytic hemolytic anemia Hereditary spherocytosis Immunohemolytic anemias (Autoimmune hemolytic anemias) In association with hemolysis induced by splenomegaly in patients with cirrhosis Clostridial infections Ceain snake envenomations G6PD deficiency (few spherocytes)
Reticulocyte count
Osmotic fragility test
Coombs test
Bone marrow aspiration