Lessons from Wolfram Syndrome: Initiation of DDAVP Therapy Causes Renal Salt Wasting Due to Elevated ANP/BNP Levels, Rescued by Fludrocortisone Treatment.

Initiation of desmopressin acetate (DDAVP) for untreated diabetes insipidus (DI) in Wolfram syndrome (WS) causes abrupt volume expansion resulting in particularly high secretion of Atrial Natriuretic Peptide (ANP) and/or Brain Natriuretic Peptide (BNP), which in turn blocks all stimulators of zona glomerulosa steroidogenesis, resulting in secondary mineralocorticoid deficiency and acute hyponatremia, causing renal salt wasting (RSW). Two sisters, a 19-y-old girl (A) and a 7-y-old girl (B) with WS, presented with severe polyuria-polydipsia due to never treated DI. Both had neurogenic bladder and "B" had severe hydronephrosis secondary to untreated grade III bilateral vesicoureteral reflux. They initiated therapy with oral melt DDAVP which resulted in RSW. ANP was found ×50 and BNP ×2-4 fold elevated. Fludrocortisone 100-200 × 2 µg/d controlled natriuresis and restored electrolytes to normal within 48 h. Fludrocortisone treatment rescues otherwise potentially life-threatening hyponatremia due to RSW and the secondary mineralocorticoid deficiency driven by elevated ANP and/or BNP, caused by sudden volume expansion following DDAVP initiation.

Wiskott-Aldrich Syndrome Misdiagnosed as Immune Thrombocytopenic Purpura: A Case Report.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked immunodeficiency characterized by various clinical phenotypes. We report the case of a 3-year-old immigrant boy presenting with persistent infant-onset thrombocytopenia treated for refractory immune thrombocytopenic purpura. Sequence analysis confirmed the diagnosis of WAS. The patient responded neither to IV infusions of immunoglobulin (Ig) nor a thrombopoietin receptor agonist and is currently planned for stem cell transplantation. Raised awareness is thus vital of this potentially misdiagnosed and lethal disorder. The diagnosis of WAS should be considered in all males with infant-onset immune thrombocytopenic purpura-like features, especially, if mean platelet volume is decreased (<7 fL) and good increment to platelet transfusions are evident.