Management of Diabetes Insipidus Following Acute Tubular Injury

Diagnosis and Classification

The American College of Physicians recommends initial assessment of serum sodium, serum osmolality, and urine osmolality to confirm diagnosis of DI, characterized by polyuria, polydipsia, and inappropriately dilute urine with high-normal or elevated serum sodium 1
Plasma copeptin levels can help distinguish between central and nephrogenic DI, with levels >21.4 pmol/l suggesting nephrogenic DI and levels <21.4 pmol/l indicating central DI 1, 2
Genetic testing is recommended for suspected nephrogenic DI to confirm diagnosis, particularly in cases with partial AVP insensitivity 3, 1
MRI of the brain with pituitary or sellar cuts should be performed for all patients presenting with DI following acute tubular injury to rule out other causes 4

Free access to fluid is essential in all patients with DI to prevent dehydration, hypernatremia, and associated complications 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, 3
In hospitalized patients with DI, close observation of clinical status, including neurological condition, fluid balance, weight, and electrolytes is necessary 3
Consider placement of a urinary catheter to ensure proper monitoring of diuresis in acute settings 3

Thiazide diuretics combined with a low-salt diet can reduce diuresis by up to 50% 1
Prostaglandin synthesis inhibitors (NSAIDs) may be added to the treatment regimen for symptomatic patients 1, 5
Amiloride should be added to thiazide in patients who develop hypokalemia 1
Low protein diet is recommended to reduce renal osmotic load and minimize urine volume 1

In patients with acute tubular injury who develop DI, careful attention must be paid to volume status as diabetes is an independent risk factor for acute renal failure in the perioperative period 6
Salt supplementation should be avoided in patients with secondary nephrogenic diabetes insipidus following tubular injury, as it could worsen polyuria and risk hypernatremic dehydration 5

Regular assessment of serum electrolytes, urine volume, urine osmolality, and body weight is crucial 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 1
Each patient with DI should have an emergency plan, including a letter explaining their diagnosis with advice regarding intravenous fluid management 1

Avoid salt supplementation in patients with secondary nephrogenic diabetes insipidus as it could worsen polyuria and risk hypernatremic dehydration 5
NSAIDs used for nephrogenic DI are contraindicated during pregnancy and should be used with caution in patients with renal impairment 1