**2.4 Hemolysis**

Cholelithiasis is a well-known complication in pediatric patients with hemolytic anaemias like sickle cell disease, hereditary spherocytosis etc. The prevalence rate of gall stones in sickle cell disease ranges from 30 to 70% which increases progressively with age and is usually not seen before the age of five [13]. The prevalence of pigment gallstones in sickle cell disease is around 10% in children under 10 years of age, which increases to 40% in those aged 10–18 years, and 50% in adults [14–16]. The prevalence of gallstones in hereditary spherocytosis is 10–20% in children, while it raises to 40% in adult population [17, 18]. Incidence of gall stones in thalassemia is low as compared to sickle cell disease [19, 20]. Thalassaemic who also has Gilbert's syndrome genotype shows higher prevalence of gall stones [21, 22]. Whenever a child or adult with sickle cell disease experiences an episode of abdominal pain, cholelithiasis or biliary colic should be considered as differential diagnosis along with vaso-occlusive crisis. In sickle cell disease mutated red blood cells in the oxygenated form do not cause any problems, however in the deoxygenated form, they acquire sickle-like shape due to bond formation between replaced amino acid and globin molecules. This change in shape of red blood cells is reversible by reoxygenation however, changing shape again and again ruptures the cell membrane, which leads to hemolysis [23]. The bilirubin which is produced by hemolysis, further conjugated in the liver and excreted in the intestine as urobilinogen which is further absorbed and excreted multiple times through the enterohepatic circulation of bile.in hemolysis the abundance of urobilinogen in the bile leads to precipitation which may become calcified, which if continuous leads to gall stone formation [24].
