Hemolytic uremic syndrome: epidemiological and clinical features of a pediatric population in Tuscany.

We retrospectively analyzed etiological, pathological and clinical features of the patients with hemolytic uremic syndrome (HUS) observed in the Pediatric Nephrology Unit at AOU Meyer of Florence. From January 1997 to December 2008, 22 cases were identified, with an annual incidence of 0.05 cases per 100,000 inhabitants, and 0.34 cases per 100,000 children <15 years old. 60% of the patients were D+ and 40% were D-, with an age distribution from 12 days to 13 years. Twenty patients (90%) had oligoanuria, lasting 6.4 ± 4 days for D+ patients versus 11.8 ± 4 days for D- patients. The development of chronic kidney disease positively correlates with the initial blood pressure value, the length of oligoanuria, and hospitalization. Microbiological investigations showed an association of D+HUS with different strains of Shiga toxin-producing Escherichia coli in 54% of the cases. D-HUS was associated with complement factor H deficiency in one patient. In the other cases, the triggering factors were pertussis, urinary tract infections and upper airway infections. While clinical and prognostic features correspond with literature data, in Tuscany the annual incidence is lower, and the percentage of D-HUS patients is higher than that observed in other studies.