Management of Diabetes Insipidus
The management of diabetes insipidus (DI) requires a tailored approach based on whether it is central or nephrogenic in origin, with central DI treated primarily with desmopressin replacement therapy and nephrogenic DI managed through fluid access, dietary modifications, and medications to reduce urine output. 1, 2, 3
Diagnosis
- Suspect DI in children presenting with polyuria, polydipsia, failure to thrive, and hypernatraemic dehydration with inappropriately low urine osmolality (<200 mOsm/kg H₂O) 1
- Suspect DI in adults with unexplained polydipsia and polyuria 1
- Initial biochemical workup should include serum sodium, serum osmolality, and urine osmolality 1
- Measure plasma copeptin levels (>21.4 pmol/l suggests nephrogenic DI; <21.4 pmol/l suggests central DI or primary polydipsia) 1
- Genetic testing is recommended for suspected congenital nephrogenic DI, particularly testing for AVPR2 and AQP2 genes 1
- Response to desmopressin administration helps differentiate central DI (positive response) from nephrogenic DI (no response) 2, 4
Management of Central Diabetes Insipidus
Pharmacological Management
- Desmopressin (DDAVP) is the first-line treatment for central DI 2, 4, 5
- Available formulations:
- Dosing should be individualized based on patient response, with careful titration to avoid hyponatremia 5, 7
- Subcutaneous administration is preferred for infants or patients with postoperative/posttraumatic brain injury being monitored for transient DI 6
Fluid Management
- Allow ad libitum access to fluid to prevent dehydration 1, 2
- Patients capable of self-regulating should rely on their thirst sensation rather than prescribed fluid amounts 1
- For patients who cannot self-regulate fluid intake (infants, cognitive impairment), offer water frequently 1
Monitoring
- Regular monitoring of serum electrolytes, urine volume, osmolality, and body weight 2
- Watch for signs of water intoxication and hyponatremia, the major complication of desmopressin therapy 5
- Ultrasound of the urinary tract every 2-3 years to detect potential complications 2
Management of Nephrogenic Diabetes Insipidus
Fluid Management
- Ensure ad libitum access to fluid to prevent dehydration, hypernatraemia, growth failure, and constipation 1
- For patients requiring fasting (>4h), provide intravenous 5% dextrose in water at maintenance rate with regular blood glucose monitoring 1
Dietary Management
- For infants, provide normal-for-age milk intake instead of water to ensure adequate caloric intake 1
- Implement careful spacing of oral feeds to reduce vomiting episodes 1
- Consider tube feeding (nasogastric or gastrostomy) for patients with repeated vomiting, dehydration, or growth failure 1
- Consult with a dietitian experienced in NDI for nutritional guidance 1
Pharmacological Management
- Combination of thiazide diuretics and prostaglandin synthesis inhibitors (COX inhibitors) is recommended for symptomatic patients 1
- Thiazide diuretics reduce urine output by inducing mild volume depletion, most effective when combined with a low-salt diet 1
- Consider adding amiloride for patients who develop thiazide-induced hypokalemia 1
- Close monitoring of fluid balance, weight, and biochemistry is essential when starting drug treatment 1
Special Considerations
- Desmopressin is ineffective and not indicated for nephrogenic DI 4
- Drug treatment for nephrogenic DI is often discontinued with increasing age as patients develop better self-management strategies 1
- Patient education is crucial to avoid water intoxication and hyponatremia, particularly for those on desmopressin 6
- Management is particularly challenging in adipsic patients (lack of thirst) and young children during intercurrent illness 7