Spherocytosis is a a blood disorder
Pathophysiology
1) disorder of red blood cell membrane 2) instability occurs with loss of membrane lipid, which decreases the surface area 3) this causes affected RBCs to be less deformable
Signs and Symptoms
1) hemolytic anemia 2) splenomegaly 3) intermittent jaundice with the most severe episodes in neonatal period 4) symptoms worsened by stress, fatigue, cold, pregnancy, other illnesses (esp. viral infections) 5) can range from asymptomatic to a fulminant hemolytic anemia
Characteristic Test Findings
Laboratory – 1) abnormal osmotic fragility test 2) mild anemia 3) usually with normal MCV despite reticulocytosis 4) increased serum bilirubin 5) can range from asymptomatic to a fulminant hemolytic anemia
Histology/Gross Pathology
1) hallmark – microspherocytes seen on peripheral blood smear 2) cells become increasing spherical as they age 3) after splenectomy, erythrocyte life span improves but never becomes completely normal
Associated Conditions
1) gallstones (almost 100% of cases 2) hemosiderosis (from transfusion-induced iron overload) 3) immune hemolytic anemia 4) G6PD deficiency 5) heterotopic bone marrow in renal pelvis
Biochemistry
1) cause is a deficiency in one of more of the red blood cell cytoskeleton proteins spectrin, ankyrin, band 3, or protein 4.2 (palladin) 2) each specific defect results in a slightly different clinical picture
Inheritance/Epidemiology
1) most common of hereditary hemolytic anemias of northern European descent (1/5000) 2) inheritance is autosomal dominant (50%), autosomal recessive (25%), and sporadic (25%)
Treatment
1) mainstay is splenectomy (except in autosomal recessive form) 2) every attempt is made to avoid splenectomy in children because of overwhelming postsplenectomy sepsis (especially with pneumococcus)
Tips for USMLE
if the patient is 18 years of age with a severe attack of gallstone cholecysitis, a hemoglobin of 10/6 g/dL, and scattered spherocytes on peripheral blood smear, think spherocytosis
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