Diabetes Insipidus: Diagnosis, Management, and Treatment Recommendations

• Diabetes Insipidus Overview:
  • Diabetes insipidus involves polyuria, urine hypotonicity, and hypernatremia.
  • Quantitative criteria for diagnosis include urine output greater than 200 mL/hr, urine osmolality less than 150 mOsm/kg, and plasma sodium greater than 145 mEq/L.
• Central Diabetes Insipidus:
  • Caused by a lack of antidiuretic hormone (ADH) due to injury to the anterior hypothalamus, pituitary stalk, or posterior pituitary gland.
  • Common causes in acute critically ill patients include surgery for pituitary tumors, cerebral trauma, intracranial hypertension, and brain death.
• Clinical Presentation and Complications:
  • Patients with untreated diabetes insipidus usually develop urine outputs of 10–15 L/day and may experience dehydration and hypernatremia.
  • Symptoms of hypernatremia include confusion, lethargy, coma, and seizures.
• Differential Diagnosis:
  • The intake of diuretic drugs, hyperglycemia, fluid overload, and fluid mobilization are considerations.
  • The administration of diuretics, hyperglycemia-induced osmotic diuresis, and hypervolemia can mimic diabetes insipidus symptoms.
• Diagnostic Differentiation:
  • Copeptin has been identified as a useful biomarker for differentiating primary polydipsia and various forms of diabetes insipidus.
  • Its role is particularly significant in chronic states of hypotonic polyuria and during diagnostic tests.
• Treatment Options:
  • Management of central diabetes insipidus includes reduction of excessive urine output and correction of water deficit.
  • Vasopressin or its synthetic analog desmopressin acetate are effective for treating polyuria.
• Vasopressin and Desmopressin:
  • Vasopressin has antidiuretic, vasoconstrictive, and oxytocic effects, while desmopressin primarily retains antidiuretic action.
  • Desmopressin is recommended for prolonged effects and is appropriate for various routes of administration.
• Lypressin and Hemostatic Effects:
  • Lypressin is an ADH analog used intranasally, but its effectiveness is limited by a short duration of action.
  • Desmopressin is also known to increase factor VIII and von Willebrand factor levels and is used in patients with coagulation disorders and significant bleeding during surgical procedures.
• Central Diabetes Insipidus Management:
  • Desmopressin initial dose: 10–20 μg intranasally, repeat every 30–60 minutes until urine output <100 mL/hr. Total appropriate dose: 10–60 μg. Repeated when urine output >200 mL/hr. Dosage must be reduced if urine output excessively decreased. Subcutaneous route seldom used. Systematic administration not recommended in ICU cases.
  • Desmopressin injection: Intravenously if intranasal route not available. Initial dose: 2–20 μg, repeated as 2- to 4-μg boluses. Vasopressin therapy risks include arterial hypertension, myocardial infarction, and mesenteric infarction.
• Management of Diabetes Insipidus Complications:
  • Desmopressin may interfere with anticoagulant drugs. Excessive antidiuretic agents can result in oliguria, hyponatremia, and water intoxication. Patients with chronic diabetes insipidus may continue drinking large amounts of water even if urine output is limited.
• Treatment of Acute Diabetes Insipidus:
  • Provide a sufficient amount of water to match urine output until polyuria is controlled. Correct the deficit of free water. Monitor diuresis and ongoing urinary losses hourly.
• Nephrogenic Diabetes Insipidus:
  • Characterized by renal insensitivity to ADH. Treatment includes low-sodium, low-protein regimen, thiazide diuretics, and nonsteroidal anti-inflammatory drugs such as indomethacin.
• Key Clinical Points:
  • Diabetes insipidus is characterized by polyuria, urine hypotonicity, and hypernatremia. Central diabetes insipidus results from a lack of ADH; nephrogenic diabetes insipidus results from renal insensitivity to ADH. Clinical signs are related to dehydration and hypernatremia.
• Differential Diagnosis and Polyuria Control:
  • ICU patients generally are unable to compensate for excessive urine losses by drinking. The differential diagnosis includes administration of diuretics, mannitol, and iodinated agents. Polyuria is controlled with desmopressin and water deficit is corrected with enteral water or intravenous 5% dextrose in water.
• Responsible Water Infusion:
  • Infuse water at rates of 1–2 L/hr through a functional gastrointestinal system. Otherwise, isotonic dextrose should be infused intravenously. Plasma electrolytes should be monitored every 4 hours until normal natremia is restored.
• Monitoring and Hyperglycemia Treatment:
  • Monitor diuresis hourly and compensate ongoing urinary losses. Correct water deficit over a few hours. Monitor blood glucose closely and treat hyperglycemia aggressively using intravenous insulin.