Management of Diabetes Insipidus

Diagnosis and Classification

The American Academy of Nephrology recommends suspecting diabetes insipidus in patients presenting with polyuria, polydipsia, and inappropriately dilute urine (urine osmolality <200 mOsm/kg H₂O) with high-normal or elevated serum sodium 2
Early genetic testing is strongly recommended for suspected nephrogenic diabetes insipidus (NDI) to confirm diagnosis, with a strength of evidence level of high 2, 3
Measurement of serum sodium, serum osmolality, and urine osmolality is recommended as initial biochemical work-up, with plasma copeptin levels helping to distinguish between different types of diabetes insipidus 3, 4
Plasma copeptin levels >21.4 pmol/l suggest nephrogenic diabetes insipidus, while levels <21.4 pmol/l should prompt testing for central diabetes insipidus, based on moderate-quality evidence 4

Free access to fluid is essential in all patients with NDI to prevent dehydration, hypernatraemia, growth failure, and constipation, with a strength of evidence level of high 6, 4
Patients capable of self-regulating should determine their fluid intake based on thirst sensation rather than prescribed amounts, while those who cannot self-regulate should be offered water frequently, based on low-quality evidence 4, 5
When fasting is required (>4h), intravenous 5% dextrose in water at maintenance rate with close monitoring is recommended, with a strength of evidence level of moderate 4

A low salt (≤6 g/day) and protein diet (<1 g/kg/day) with dietetic counseling is recommended to reduce renal osmotic load and minimize urine volume, based on moderate-quality evidence 7, 6
Normal-for-age milk intake (instead of water) is recommended for infants with NDI to ensure adequate caloric intake, with a strength of evidence level of low 6, 8
Tube feeding should be considered in infants and children with repeated episodes of vomiting, dehydration, and/or failure to thrive, based on low-quality evidence 6, 8

Thiazide diuretics and prostaglandin synthesis inhibitors are recommended for symptomatic infants and children with NDI, with a strength of evidence level of moderate 6, 8
Thiazide diuretics can reduce diuresis by up to 50% in the short term when combined with a low-salt diet, based on moderate-quality evidence 8
Amiloride should be added to thiazide in patients who develop hypokalemia, with a strength of evidence level of low 6
Prostaglandin synthesis inhibitors are contraindicated during pregnancy, and should be considered for discontinuation once patients reach adulthood or achieve complete continence, based on moderate-quality evidence 7

Regular assessment of height and weight, especially in children, is recommended, with a strength of evidence level of high 6
Monitoring of basic plasma (Na, K, Cl, HCO₃, creatinine, osmolality) and urine (osmolality) biochemistry is recommended, based on moderate-quality evidence 6
Kidney ultrasound should be performed at least once every 2 years to monitor for urinary tract dilatation and/or bladder dysfunction caused by polyuria, with a strength of evidence level of low 6
Evaluation of treatment efficacy via urine osmolality, urine output, weight gain, and growth is recommended, based on moderate-quality evidence 6

Each patient with NDI should have an emergency plan, including a letter explaining their diagnosis with advice regarding intravenous fluid management, with a strength of evidence level of high 7
Intravenous rehydration with water and dextrose or glucose (e.g., 5% dextrose) is recommended, based on moderate-quality evidence 7
Close observation of clinical status, including neurological condition, fluid balance, body weight, and serum electrolytes, is recommended, with a strength of evidence level of high 7