This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)

Moya, et al., describe an infant male who was screened positive in a post-natal screening program for cystic fibrosis. The screening method was based on detecting raised levels of a pancreatic enzyme (immunoreactive trypsin -- IRT) in serum. During the course of the subsequent investigation it was determined the infant had concentrated serum (high sodium concentration) and dilute urine (a low particle-to-solvent ratio which indicated his urine was not being concentrated), together with a high urine excretion rate of the antidiuretic hormone arginine vasopressin (AVP). A sweat test (for cystic fibrosis) was negative as was DNA analysis for 3 common mutations causing cystic fibrosis. The investigations, therefore, confirmed congenital nephrogenic diabetes insipidus but excluded cystic fibrosis.

The authors point out that NDI was a cause of a false positive screen for cystic fibrosis when using IRT as the screening system. The mechanism for this is unclear and cannot be solely attributed to the dehydration often caused by NDI.