Plasma and urine electrolyte concentrations and vasopressin levels in patients admitted to hospital for falciparum malaria.

Vasopressin levels, together with plasma and urinary electrolytes, were measured in the acute and convalescent stages of 17 patients with malaria and 11 patients with other febrile illnesses. There was a significantly lower serum sodium in the acute stages of both groups (p less than 0.01 and p less than 0.02). There was no significant difference between the malaria and control groups. There were no significant changes in the vasopressin levels, although one patient with malaria showed evidence of inappropriate vasopressin secretion which returned to normal after treatment. This study suggests the mild hyponatraemia sometimes seen in the acute stages of malaria is not related to inappropriate secretion of vasopressin, although this condition may be of importance in more severe cases of hyponatraemia.