Clinical course of 63 children with hereditary spherocytosis: a retrospective study years). The median follow-up time was 4.6 years. The main reasons for referral to a specialist service were anemia of undetermined etiology in 16 patients (25%) and anemia that was unresponsive to iron supplementation in 8 (12.7%). The predominant clinical manifestations at diagnosis were splenomegaly in 44 patients (69.8%), anemia in 40 (63.5%) and jaundice in 24 (38%). A positive family history was recorded for 36 patients (57%; 95% confidence interval: 44.9-69.4%), twenty-two patients (35%) were considered the first case in the family and for five children information was not recorded. Eleven fathers (17.5%) and 14 mothers (22.2%) had positive red cell osmotic fragility tests of which three fathers and three mothers were asymptomatic. The baseline morphologic examination of peripheral blood smears of 51 patients showed that 23 patients (45%) had spherocytic red cells and the median Hb concentration was 10.0 g/dL. In 51 patients the median reticulocyte count was 6.3%, the indirect bilirubin concentration for 34 patients was 1.9 mg/dL and median lactate dehydrogenase (LDH) concentration was 667 IU for 13 patients. Clinical characteristics according to the severity of clinical presentation are presented in Table 1. Sixteen (25.4%), 34 (54%) and 13 (20.6%) patients were classified as mild, moderate and severe, respectively. There was no significant difference regarding gender, family history and number of splenectomized patients between the three groups. However, age at diagnosis was significantly different. Patients classified as severe, had a median age at diagnosis of 0.5 years, whereas those classified as mild or moderate were approximately 10 and 5 years old, respectively (p-value = 0.001). During the follow-up, 17 patients (27%) developed cholelithiasis as identified by gallbladder ultrasonography. The median age at diagnosis of gallstones was 10 years old (range: 4.8-18.3 years). Of these patients, 10 (15.9%), with a mean age of 12 years old, were submitted to cholecystectomy. There was no significant difference between groups regarding the probability of cholelithiasis. As estimated by survival analysis, the probabilities of cholelithiasis at 10 years for children with mild, moderate and severe HS were 15%, 24% and 10%, respectively. At 20 years, with a much smaller number of patients followed for this period, the probability was 40%, 80% and 10% for patients with mild, moderate and severe disease, respectively (Figure 1). Other frequent complications were splenic sequestration and aplastic crisis in 14 (22.2%) and 3 (4.8%) patients, respectively. Thirty-five patients (55.6%) under- went blood transfusions during follow-up. There were no deaths during the follow-up. The need of transfusions was significantly more common for patients classified with severe disease (p-value = 0.004). Twenty-two patients (36%) underwent splenectomy with the main indication for the procedure being spleen sequestration in 9 (14%) patients. The median age at Rev Bras Hematol Hemoter. 2012;34(1):9-13 Figure 1 – Probability of having cholelithiasis according to the severity of the presentation splenectomy was 7 years (range: 9.8 months-21 years). The probability of splenectomy at 10 years of age for mild, moderate and severe disease was 9%, 38%, and 55%, respectively (p-value = 0.005). The median age for the severe group was about 6 and a half years old and the moderate, 12 years old (Figure 2). Figure 2 – Probability of having been submitted to splenectomy according to the severity of the presentation Discussion The commonest cause of anemia in children, worldwide, is iron deficiency. Hemolysis is a relative uncommon cause. In pediatrics, hemolytic anemia is commonly associated with hemoglobinopathies, erythro- enzymopathies or red cell membrane disorders, such as HS. HS has been reported in all ethnic groups, however, few cases have been reported in Black populations.(1,3,13) The incidence of HS is unknown in Brazil. Although HS is a relatively common cause of hemolytic anemia, there have been few clinical studies regarding its clinical course and management. The diagnosis of HS is generally straightforward, based on a combination of the clinical examination and family history, and on physical and laboratory examinations.(1) In the current study the median age at diagnosis was about 5 years, ranging from 5 months to 21 years. As reported in the literature, the diagnosis of HS is often made in childhood 11