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We evaluated, both in toilet-trained and not-toilet-trained children, the impact of cleaning the genital area with plain water on the false positive rate at urine dipstick, and evaluated which factors could be associated to falsely positive findings. We prospectively enrolled 612 patients consecutively attending our nephro-urological outpatient clinic. Firstly, we performed urine dipsticks on urine samples collected from patients whose genital area had not been cleaned before. Then we collected a second sample from the patients with positive urine dipstick, after their genital area had been cleaned with plain water. The urine dipstick was considered falsely positive if we documented its normalization at urine dipstick made on the urine sample collected after cleaning the genital area. We found a falsely positive urine dipstick in 25.5% of the patients, and more in detail in 22.9% of the not-toilet-trained children, and in 26.6% of the toilet-trained children (p = 0.37). The only factors leading to a significant increased RR to have a false positive were non-retractable foreskin (RR = 4.38; 95% CI, 2.15–8.9; p = 0.0001) and female gender (RR = 2.47; 95% CI, 1.77–3.44; p < 0.0001). Conclusion: Cleaning the genital area with plain water should always be performed before collecting urine samples, even if only a urine dipstick without culture is needed.What is Known:• Cleaning the genital area reduces the urine bacterial contamination rate in populations of toilet-trained pediatric patients.• There are no studies assessing the impact of cleaning the genital area on the quality of the urine dipstick, nor on which factors could affect the urine dipstick findings.What is New:• Falsely positive urine dipstick was found in 25.5% of the 612 prospectively enrolled toilet-trained and not-toilet-trained children.• Non-retractable foreskin and female gender significantly increases the relative risk of falsely positive urine dipsticks.

Recently it has been clearly established that partial deficiency of spectrin (SP) evaluated by radioimmunoassay is a common feature of many different forms of hereditary spherocytosis (HS). In this paper the determination of SP density (spectrin/band 3 ratio) in 46 HS patients and in 50 normal controls is presented. The comparison between the membrane SP density of HS subjects and controls showed a statistically significant difference (P less than 0.0005). Moreover no overlap between normal and HS subjects was observed. Membrane spectrin/band 3 ratio has been found related to some clinical features: indeed patients with severe HS showed a smaller SP density than those with milder HS. Our results show that the evaluation of membrane SP density permits a prompt diagnosis of HS and avoids extensive and unnecessary studies for other anaemias.