Diagnosis and Management of Central and Nephrogenic Diabetes Insipidus

Clinical Presentation and Diagnosis

The American College of Radiology recommends measuring sodium serum, serum osmolality, and urine osmolality simultaneously as an initial evaluation, with a combination of inappropriately diluted urine (<200 mOsm/kg H₂O) and high-normal or elevated serum sodium being pathognomonic of diabetes insipidus 1, 2, 3
The European Society of Endocrinology suggests that copeptina plasma levels are the primary differentiating test, with elevated copeptina confirming nephrogenic diabetes insipidus (indicating significantly elevated ADH levels) and low or absent copeptina suggesting central diabetes insipidus 4, 3
The American Academy of Pediatrics recommends genetic testing early in patients with suspected nephrogenic diabetes insipidus, with ~90% of cases being X-linked due to pathogenic variants in AVPR2 (vasopressin V2 receptor) and <10% being autosomal due to variants in AQP2 (aquaporin-2) 1, 2

The American College of Radiology recommends MRI of the sella turcica with contrast using high-resolution pituitary protocols as the preferred study for central diabetes insipidus, with T1 fine-cut sequences identifying the typical hyperintensity of normal neurosecretory granules and evaluating the hypothalamic-neurohypophyseal axis for masses or infiltrative processes 5, 6
The European Society of Radiology suggests that ultrasound of the kidneys should be performed at least every 2 years to monitor urinary tract dilation and secondary bladder dysfunction due to polyuria 3

The American College of Endocrinology recommends desmopresina as the treatment of choice for central diabetes insipidus (including partial), with consideration of alternative routes of administration when the intranasal route is compromised 4, 3
The International Society of Nephrology suggests initiating combined therapy with thiazide diuretics and prostaglandin synthesis inhibitors (NSAIDs) in symptomatic infants and children with nephrogenic diabetes insipidus, with monitoring of fluid balance, weight, and biochemistry being essential 2, 4, 3
The Academy of Nutrition and Dietetics recommends dietary modifications, including a low-salt diet (≤6 g/day) and protein restriction (<1 g/kg/day), to reduce renal osmotic load 3

A normal serum osmolality does not rule out diabetes insipidus, as certain clinical scenarios can present with normal osmolality despite the diagnosis, according to the American Gastroenterological Association 7
Normal osmolality does not rule out other forms of dehydration, particularly volume depletion from gastrointestinal or renal sodium losses, which present with normal or low plasma osmolality, as stated by the Clinical Nutrition Society and the American Gastroenterological Association 7, 8

If a patient presents with polyuria and polydipsia, proceed with full diabetes insipidus evaluation even if initial serum osmolality is normal, as recommended by the American Gastroenterological Association 7