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Three new equations for calculating the estimated basal serum creatinine (ebSCr) in hospitalized children have been developed: the simplified acute kidney injury (AKI) baseline creatinine (ABC) equation which considered only age in the formula; the equation including age and minimum creatinine (Crmin) within the initial 72 h from hospitalization (ABC-cr); and the equation including Crmin and height, weight, and age as squared values (ABC-advanced). We aimed to test the diagnostic performance of the ABC, ABC-cr and ABC-advanced equations in diagnosing AKI in 163 prospectively enrolled children with type 1 diabetes mellitus (T1DM) onset. We considered measured basal serum creatinine (mbSCr), the creatinine measured 14 days after T1DM onset. AKI was defined by the highest/basal serum creatine (HC/BC) ratio > 1.5. On the basis of the mbSCr, the AKI was diagnosed in 66/163 (40.5%) patients. This prevalence was lower than the prevalence of AKI diagnosed on the basis of ABC ebSCr (122/163 patients; 74.8%) (p < 0.001) and similar to the prevalence of AKI diagnosed on the basis of ABC-cr ebSCr (72/163 patients; 44.2%) (p = 0.5) and to the prevalence of AKI diagnosed on the basis of ABC-advanced ebSCr (69/163; 42.3%) (p = 0.73). AKI determined using ABC ebSCr, ABC-cr ebSCr and ABC-advanced ebSCr showed, respectively, 63.5% (kappa = 0.35; p < 0.001), 87.7% (kappa = 0.75; p < 0.001), and 87.1% (kappa = 0.74; p < 0.001) agreement with AKI determined using mbSCr. Using the HC/BC ratio calculated on the basis of mbSCr as gold standard, for Bland–Altman plots the HC/BC ratio calculated on the basis of ABC formula presented higher bias and wider limits of agreement compared with the HC/BC ratio calculated on the basis of ABC-cr and ABC-advanced formulas. In the receiver–operating characteristics (ROC) curve analysis the HC/BC ratio calculated on the basis of ABC ebSCr presented lower area under the ROC curve (AUROC) (AUROC = 0.89; 95%CI: 0.85–0.95; p < 0.001) compared with HC/BC ratio calculated on the basis of ABC-cr (AUROC = 0.94; 95%CI: 0.91–0.98; p < 0.001) or ABC-advanced ebSCr (AUROC = 0.914; 95%CI: 0.91–0.97; p < 0.001). In both Bland–Altman plots and ROC curve analysis, the ABC-cr and ABC-advanced formulas performed similarly. In conclusion, the ABC-cr and ABC-advanced formulas present very good diagnostic performance toward AKI identification in a population of children with T1DM onset.

Summary: Gyrate atrophy of the choroid and retina is an autosomal recessive chorioretinal dystrophy which leads to a slowly progressive loss of vision. The primary defect is due to a deficiency of the enzyme ornithine δ-aminotransferase, which is responsible for markedly elevated levels of ornithine in plasma and other body fluids. Although several therapeutic regimens have been proposed, the reduction in ornithine accumulation obtained by reducing the intake of its precursor arginine (semisynthetic low-arginine diet) is the one most practised. In this clinical and molecular study we report a patient with hyperornithinaemia and gyrate atrophy of the choroid and retina who had been diagnosed when she was 3 years 9 months old. She also presented mild mental retardation, delayed language development and speech defects. The patient has recently been found to be homozygous for the new Gly91Arg amino acid substitution of the enzyme ornithine δ-aminotransferase. This mutation lies in a region of the mature protein that is considered crucial for the mitochondrial targeting activity. In this patient, a 28-year treatment with a completely natural low-protein diet (0.8 g/kg per day of natural protein) has been able to significantly reduce ornithine plasma levels, and to greatly delay the natural progression of the chorioretinal changes. This study suggests that, in the long-term treatment of gyrate atrophy, the efficacy in slowing the progression of chorioretinal changes and the palatability of a completely natural low-protein diet make this treatment a potentially viable alternative in patients refusing the semisynthetic diet.