An unusual case of hyponatraemia in diabetic ketoacidosis.

This report outlines a case of diabetic ketoacidosis associated hyponatraemia in an 18 year old woman with type 1 diabetes who presented to the accident and emergency department and was quickly admitted to the intensive treatment unit. Causes of hyponatraemia include sodium depletion, pseudohyponatraemia, and extracellular hypertonicity. Hypertonicity secondary to hyperglycaemia is thought to be the major cause of hyponatraemia in diabetic ketoacidosis. Indirect and direct sodium measurements were performed until the glucose concentration stabilised. The large difference between the presenting sodium concentrations is consistent with pseudohyponatraemia. However, the causes of pseudohyponatraemia (large increases in total protein, triglyceride, and cholesterol concentrations) were excluded. Analytical error should always be considered when the laboratory results do not agree with the clinical picture. Sometimes, however, even after excluding all known effects, the cause may remain unexplained, as in this case.