Tolvaptan is successful in treating inappropriate antidiuretic hormone secretion in infants

Aim: Using fluid restriction to treat the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in infants is potentially hazardous, as fluid intake and caloric intake are connected. Antagonists for the type 2 vasopressin receptor have demonstrated efficacy in adult patients with SIADH, but evidence in children is lacking. We reviewed our experience from two cases in the UK.

Methods: This was a retrospective review of the clinical data on two patients diagnosed with SIADH in infancy and treated with tolvaptan, an oral vasopressin receptor antagonist.

Results: Persistent hyponatraemia was noted in both patients in the first month of life and eventually led to SIADH diagnoses. Initial salt supplementation in one patient resulted in severe hypertension, treated with four antihypertensive drugs. Tolvaptan was commenced at two and four months of age, respectively, and was associated with normalisation of plasma sodium values and blood pressure without the need for antihypertensive treatment. There was transient hypernatraemia in one patient, which was normalised with a dose reduction. Tolvaptan was administered by crushing the tablet and mixing it with water.

Conclusion: Tolvaptan provided effective treatment for SIADH in both infants and could be administered orally.