Different alterations of glomerular filtration rate and their association with uric acid in children and adolescents with type 1 diabetes or with overweight/obesity.

BACKGROUND: Hyperfiltration (HF) occurs early in diabetes or obesity (OB)-associated renal disease. Alterations of glomerular filtration rate (GFR) in childhood OB remain unclear. OBJECTIVES: To compare the prevalence of GFR alterations and its association with uric acid in children and adolescents with type 1 diabetes (T1D) vs overweight (OW)/OB. METHODS: Cross-sectional study of 29 youths (aged: 13 ± 2 years) with T1D (disease duration: 7 ± 3 years) and 165 with OW/OB (aged: 11 ± 3 years). Patients with an albumin-creatinine ratio >3.39 mg/mmol were excluded. GFR was estimated with creatinine-cystatin C Zappitelli equation. HF and low GFR were defined by a GFR > 135 and <90 mL/min.1.73 m2 , respectively. RESULTS: HF was higher in children with T1D vs OW/OB (28% vs 10%, P < .005). Children with OW/OB also showed a 10% of low GFR. In patients with T1D, HbA1c (ß = .8, P < .001), and systolic blood pressure (ß = 11.4, P < .005) were independent predictors of GFR (R2 = .65). In OW/OB, HF cases were almost limited to prepubertal children and low GFR to pubertal ones. GFR in OW/OB was associated with age (ß = -2.2, P < .001), male sex (ß = -11.6, P < .001), and uric acid (ß = -.05, P < .001) in adjusted models (R2 = .33). CONCLUSIONS: GFR alterations were different between youths with T1D and with OW/OB. Higher uric acid, older age, and puberty were related to lower GFR values in OW/OB children. Longitudinal studies will determine if low GFR is consequence of a rapid GFR decline in pediatric patients with OW/OB.

Effects of Pubertal Status and Inflammation on the Use of Ferritin to Define Iron Deficiency in Children With Overweight or Obesity.

BACKGROUND AND AIMS: A worldwide increase in childhood overweight (OW) and obesity (OB) has been reported. OB is an inflammatory state which affects iron metabolism and the sensibility of the tests to detect iron deficiency (ID). Our aim was to evaluate the adequacy of current ferritin cut-offs to define ID in children with OW/OB. METHODS: This cross-sectional study included 152 children (54% girls) aged (median [Q1-Q3]) 11 (8-13) years with OW/OB. Complete blood count and iron metabolism were evaluated. Low ferritin, transferrin saturation (TSat), and anemia were defined by age- and sex-specific cut-offs recommended by National Guidelines. Iron intake was assessed in a subgroup (n = 80) by a 24-hour dietary recall. Analyses were made according to pubertal development and ferritin tertiles. RESULTS: The overall prevalence of low ferritin, TSat, and anemia was 2.6%, 23.8%, and 5.2%, respectively. Among pre-pubertal children (n = 87), the frequency of low TSat rose across ferritin tertiles (P < .05), whereas it decreased among pubertal children (n = 65; P < .005). Cases of anemia among pre-pubertal children were found in the highest ferritin tertile, whereas 4/6 anemia cases in pubertal children were found in the lowest ferritin tertile (<39 µg/L). Pubertal children within the lowest ferritin tertile + low TSat (n = 11) showed lower hemoglobin (-9%; P < .005) and hematocrit (-8%, P < .01) than those in the same tertile + normal TSat (n = 16). The overall prevalence of children with ferritin < 39 µg/L + low TSat was 9.2%. CONCLUSIONS: Higher ferritin cut-off values are required to define ID in children with OW/OB. Such cut-off remains to be validated in larger, multi-ethnic cohorts of children with OW/OB.