Hyponatremia may be seen in all of the following conditions except -

Vasopressin, secreted from posterior pituitary, is the principal regulator of tonicity,with its release largely stimulated by increase in plasma tonicity. Diabetes insipidus manifests clinically with polyuria and polydypsia and can result from either vasopressin deficiency or vasopressin insensitivity at the level of kidney.As a result, hypernatremia occurs. Page 1881 & 1882, Nelson textbook of pediatrics 19th edition