Determination of the renal threshold for glucose excretion in Familial Renal Glucosuria.

BACKGROUND/AIMS: Familial Renal Glucosuria (FRG) is characterized by the presence of persistent isolated glucosuria in the absence of hyperglycemia. Mutations in SLC5A2, the gene coding for the sodium-glucose co-transporter 2 (SGLT2), are responsible for FRG. Phenotype/genotype correlations in FRG have mostly relied on the quantification of Urinary Glucose Excretion (UGE), which is dependent on both the filtered glucose load and the renal glucose reabsorptive capacity. In the current work, the renal threshold for glucose excretion (RTG) was determined in an FRG cohort, with the purpose of characterizing the impact of SGLT2 mutations on renal glucose transport. METHODS: From January to December of 2013, eight FRG individuals with identified SLC5A2 mutations were enrolled. Patients were given a Mixed-Meal Tolerance Test during which blood glucose and UGE were measured over a 4 h period and the data was used to calculate RTG, according to a recently validated protocol. RESULTS: In patients with homozygous mutations, RTG values were very low, with a mean (SD) of 0.95 (1.17) mmol/l, compared to commonly reported values of approximately 10-11.1 mmol/l in healthy subjects. In subjects with heterozygous mutations, mean (SD) RTG values were 4.91 (1.23) mmol/l, which are approximately one-half of the values in subjects without mutations. CONCLUSIONS: In FRG, mutations in SLC5A2 lead to reductions in RTG and increases in UGE. Because determination of RTG is not influenced by the filtered glucose load, the calculated RTG values provide a more refined measure of the impact of mutations on renal glucose transport than can be obtained from UGE alone.

[Reference values for bone strength assessed by quantitative ultrasound early after birth in term and preterm neonates]. / Valores de referência de robustez óssea avaliados próximo ao nascimento por ultrassonografia quantitativa em recém-nascidos de termo e pré-termo.

AIM: To obtain reference values for bone strength assessed early after birth for term and preterm neonates in Portugal. METHODS: Speed of sound (SOS) (m/s) was measured using the quantitative ultrasound method in a systematic sample of appropriate-for-gestationalage term and preterm neonates, within the first two and five days after birth, respectively. Homogeneity of values between genders and between gestational age groups was assessed. RESULTS: A sample of 158 neonates was enrolled, 34 full-term and 124 preterm (26-41 weeks of gestation), birth weights of 595g-4195g, 84 males (53.2%) and 20 twins (10.8%). The mean of the SOS significantly increases with gestational age. Reference values of SOS for gestational age groups are provided as 10th, 25th, 50th, 75th and 90th centiles without gender distinction. CONCLUSION: Reference values for SOS early after birth are made available for term and preterm appropriate-for-gestational age neonates, reflecting the intrauterine bone status, a baseline for follow-up studies on bone strength in Portugal.