To better clarify the genetic inheritance of primary tubular hypomagnesemia-hypokalemia with hypocalciuria, or Gitelman's syndrome (GS), we studied eight families (10 patients aged 11 to 22 years; 16 parents; 9 siblings) in which at least one offspring had GS (plasma magnesium < 0.65 mmol/liter; plasma potassium < 3.6 mmol/liter; high magnesium and potassium fractional excretions; molar urinary calcium/creatinine < 0.10). Two families each had two offspring of different sex with GS, who all had tetanic episodes and/or marked weakness during childhood or adolescence, whereas in three other families two mothers and three offspring presented GS and one father and two other offspring had hypomagnesemia and hypocalciuria but normal plasma potassium. The mean plasma magnesium and potassium levels of the patients of the first two families were significantly lower (P < 0.05) than those of the other three families. Intralymphocytic but not intraerythrocytic magnesium and potassium were significantly lower (P < 0.05) in patients compared to controls. We hypothesize that there are two different types of genetic transmission of GS, one autosomal recessive and one autosomal dominant with high phenotype variability. It seems that this genetic heterogeneity is associated with a different clinical expression with frequent tetanic episodes and lower plasma potassium and magnesium levels in the autosomal recessive form.

The anthropometry-bioimpedance analysis-nutrition (ABN) score is a recently proposed objective method of assessing malnutrition in children on chronic peritoneal dialysis (CPD) that uses nine parameters based on anthropometry, skinfold thickness and bioimpedance analysis. The aim of this prospective, cross-sectional study was to apply it to children treated with CPD in seven Italian paediatric nephrology centres, with a score of < 10.33 (the 3rd percentile in a population of 264 healthy children) classifying the children as malnourished. The other considered parameters were age, age at the start of dialysis and duration of dialysis; serum haemoglobin, urea, creatinine, total protein, albumin, transferrin, bicarbonate and C-reactive protein; residual urine output; urinary and peritoneal creatinine clearance; and daily protein and energy intake. The study enrolled 43 patients (mean age 10.2 +/- 4.2 years), 21 of whom (48.8%) had an ABN score of < 10.33: 15 with mild, five with moderate, and one with severe malnutrition. The malnourished patients started CPD at a younger age (P < 0.05) and had a longer duration of dialysis (P < 0.01), and a significant worsening in nutritional status was observed in those treated for more than 12 months of dialysis; they also had significantly lower serum albumin, creatinine and haemoglobin levels. In conclusion, protein-calorie malnutrition is common in children receiving CPD. A younger age at the start of dialysis and a longer duration of treatment are clear risk factors, and counterbalance the long-term viability of CPD in paediatric age.

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