Long-term follow-up of patients with Bartter syndrome type I and II

Background. Little information is available on a long-term follow-up in Bartter syndrome type I and II. Methods. Clinical presentation, treatment and long-term follow-up (5.0-21, median II years) were evaluated in 15 Italian patients with homozygous (n = 7) or compound heterozygous (n = 8) mutations in the SLC12Al (n = 10) or KCNJ I (11 = 5) genes. Results. Thirteen new mutations were identified. The 15 children were born pre-term with a normal for gestational age body weight. Medical treatment at the last follow-up control included supplementation with potassium in 13, non-steroidal anti-inflammatory agents in 12 and gastroprotective drugs in five patients. At last follow-up, body weight and height were within normal ranges in the patients. Glomerular filtration rate was <90 mL/min/1.73 m(2) in four patients (one of them with a pathologically increased urinary protein excretion). In three patients, abdominal ultrasound detected gallstones. The group of patients with antenatal Bartter syndrome had a lower renin ratio (P < 0.05) and a higher standard deviation score (SDS) for height (P < 0.05) than a previously studied group of patients with classical Bartter syndrome. Conclusions. Patients with Bartter syndrome type I and 11 tend to present a satisfactory prognosis after a median follow-up of more than 10 years. Gallstones might represent a new complication of antenatal Bartter syndrome.