ESPN 53rd Annual Meeting

ESPN 2021


 
Long-term follow-up of patients with Bartter syndrome type III
Leire Gondra Sangroniz 1 Leire Madariaga Domínguez 2 Alejandro García Castaño 5 María Herrero Goñi 3 Mireia Aguirre Meñica 3 Ana Vinuesa Jaca 3 Nélida García Pérez 1 Sara Gomez Conde 4

1- CRUCES UNIVERSITY HOSPITAL. IIS BIOCRUCES BIZKAIA HEALTH RESEARCH INSTITUTE. UNIVERSITY OF THE BASQUE COUNTRY
2- CRUCES UNIVERSITY HOSPITAL. IIS BIOCRUCES BIZKAIA HEALTH RESEARCH INSTITUTE. UNIVERSITY OF THE BASQUE COUNTRY. CIBERER. CIBERDEM
3- CRUCES UNIVERSITY HOSPITAL. IIS BIOCRUCES BIZKAIA HEALTH RESEARCH INSTITUTE
4- IIS BIOCRUCES BIZKAIA HEALTH RESEARCH INSTITUTE
5- IIS BIOCRUCES BIZKAIA HEALTH RESEARCH INSTITUTE. UNIVERSITY OF THE BASQUE COUNTRY
 
Introduction:

Bartter Syndrome Type III (BSIII) is a clinically heterogeneous hereditary salt-losing tubulopathy. Approximately 25% of patients develop chronic kidney disease (CKD) over time. The aim of this study is to describe a cohort of patients with BSIII and to identify possible factors associated with the long-term prognosis.

Material and methods:

Clinical presentation, treatment, long-term follow-up (1-46, median 12.5 years) and molecular findings were evaluated in 53 patients. To study the phenotype/genotype correlation patients were classified into two groups according to the residual current in ClC-Kb channel (≤ 20% or > 20%).

Results:

Among 53 patients, 85% were Spanish. Median age at diagnosis was 0.67 (0.5-3) years. At diagnosis, 34% had antenatal/neonatal BS phenotype 54% classic BS, and 12% Gitelman Syndrome phenotype. Fifty percent were born prematurely (32-37 weeks). In 55% cases homozygous p.Ala204Thr and in 19% heterozygous p.Ala204Thr mutation was found. All of them except two were Spanish. At last follow-up, 72% patients had normal growth, 15% had nephrocalcinosis and in 22% CKD was detected. One patient required hemodialysis. Severe hypokalemia and metabolic alkalosis at diagnosis were related with long-term growth retardation and CKD (p<0.05). Moreover, CKD was associated with older age at diagnosis (p=0.038). All patients with CKD except three had homozygous p.Ala204Thr mutation (30% of patients with this mutation). There were no significant differences in the long-term renal prognosis depending on the clinical phenotype at diagnosis. No genotype/phenotype correlation was found in long-term prognosis.

Conclusions:

Older age and severe hypokalemic alkalosis at diagnosis are related with CKD, therefore, chronic hyperaldosteronism is a relevant risk factor for renal impairment in patients with BSIII. In addition, patients with homozygous p.Ala204Thr mutation have a very variable long-term prognosis, suggesting that patients’ genotype is probably not a relevant factor implicated in the long-term prognosis.