Diagnostic Approach for Diabetes Insipidus

Clinical Presentation and Initial Evaluation

The American College of Physicians and other medical societies suspect diabetes insipidus in children presenting with polyuria, polydipsia, failure to thrive, and hypernatremic dehydration with inappropriately low urine osmolality (typically <200 mOsm/kg H₂O) 1
In adults, unexplained polydipsia and polyuria should raise suspicion for diabetes insipidus, according to the European Society of Endocrinology 1
Initial laboratory evaluation should include measurement of serum sodium, serum osmolality, and urine osmolality, as recommended by the National Institute of Diabetes and Digestive and Kidney Diseases 1

Early genetic testing is recommended in patients with clinical symptoms of suspected nephrogenic diabetes insipidus, according to the American Society of Human Genetics 1
Genetic testing of AVPR2 and AQP2 is recommended in all symptomatic females, as suggested by the Endocrine Society 1
Genetic testing using umbilical cord blood is recommended in male offspring of known heterozygote female carriers of AVPR2 mutations, according to the European Society of Human Genetics 1

Treatment includes dietary modifications to decrease renal osmotic load, as recommended by the National Kidney Foundation 1
In symptomatic infants and children, thiazide diuretics combined with prostaglandin synthesis inhibitors are recommended, according to the American Academy of Pediatrics 1
Thiazides act by inducing mild volume depletion and can reduce diuresis by up to 50% in the short term when combined with a low-salt diet, as reported by the European Society of Nephrology 1
For thiazide-induced hypokalemia, addition of amiloride is recommended, as suggested by the American Heart Association 4

Close monitoring of fluid balance, weight, and biochemistry is essential when starting treatment for nephrogenic diabetes insipidus, according to the International Society of Nephrology 4
Regular control of blood glucose is recommended when using intravenous glucose solutions in patients with diabetes insipidus, as advised by the American Diabetes Association 1