Treatment of Diabetes Insipidus
The primary treatment for diabetes insipidus depends on the type: central diabetes insipidus is treated with desmopressin (DDAVP), while nephrogenic diabetes insipidus requires thiazide diuretics combined with prostaglandin synthesis inhibitors and dietary modifications. 1, 2
Types of Diabetes Insipidus and Diagnosis
- Diabetes insipidus should be suspected in patients presenting with polyuria, polydipsia, and inappropriately dilute urine (urine osmolality <200 mOsm/kg H₂O) with high-normal or elevated serum sodium 1
- Measurement of serum sodium, serum osmolality, and urine osmolality is recommended as initial biochemical work-up 1, 3
- Plasma copeptin levels >21.4 pmol/l suggest nephrogenic diabetes insipidus, while levels <21.4 pmol/l indicate central diabetes insipidus 1, 4
- Early genetic testing is strongly recommended for suspected nephrogenic diabetes insipidus to confirm diagnosis 3, 1
Treatment of Central Diabetes Insipidus
Desmopressin (DDAVP) Administration
- Desmopressin is the drug of choice for central diabetes insipidus due to its selective antidiuretic activity 2, 5
- Desmopressin is available in multiple formulations:
- The dose should be adjusted based on adequate duration of sleep and adequate but not excessive water turnover 6, 7
Monitoring and Safety Considerations
- Ensure serum sodium is normal before starting treatment 2
- Measure serum sodium within 7 days and approximately 1 month after initiating therapy, and periodically during treatment 2
- More frequently monitor serum sodium in patients 65 years and older and those at increased risk of hyponatremia 2
- For patients on oral formulations, evening fluid intake should be limited to 200 ml or less with no drinking until morning to prevent water intoxication and hyponatremia 6, 8
Treatment of Nephrogenic Diabetes Insipidus
Fluid Management
- Free access to fluid is essential to prevent dehydration, hypernatremia, and growth failure 1, 3
- Patients capable of self-regulating should determine their fluid intake based on thirst sensation rather than prescribed amounts 1
- When fasting is required (>4h), intravenous 5% dextrose in water at maintenance rate with close monitoring is recommended 1
Dietary Modifications
- 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 1, 4
- Normal-for-age milk intake (instead of water) is recommended for infants with NDI to ensure adequate caloric intake 3, 1
- Tube feeding should be considered in infants and children with repeated episodes of vomiting, dehydration, and/or failure to thrive 3, 1
Pharmacological Treatment
- Thiazide diuretics and prostaglandin synthesis inhibitors are recommended for symptomatic patients with nephrogenic diabetes insipidus 3, 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 3
- Amiloride should be added to thiazide in patients who develop hypokalemia 1
- Prostaglandin synthesis inhibitors are contraindicated during pregnancy 1
Emergency Management
- Each patient with diabetes insipidus should have an emergency plan, including a letter explaining their diagnosis with advice regarding intravenous fluid management 1, 4
- For nephrogenic diabetes insipidus, intravenous rehydration with water and dextrose (e.g., 5% dextrose) is recommended 1
- Close observation of clinical status, including neurological condition, fluid balance, body weight, and serum electrolytes, is essential during acute management 1
Monitoring and Follow-up
- Regular assessment of height and weight, especially in children, is recommended 1
- Monitoring of basic plasma (Na, K, Cl, HCO₃, creatinine, osmolality) and urine (osmolality) biochemistry is necessary 1
- Kidney ultrasound should be performed at least once every 2 years to monitor for urinary tract dilatation and/or bladder dysfunction caused by polyuria in nephrogenic diabetes insipidus 1, 3