Diabetes Insipidus (DI)

Definition

Diabetes Insipidus (DI) is a rare disorder of water metabolism characterized by deficient production (central DI) or renal resistance (nephrogenic DI) to antidiuretic hormone (ADH/vasopressin). It results in large volumes of dilute urine and intense thirst.

Types

• Central DI: Pituitary ADH deficiency, such as trauma, tumor, surgery.
• Nephrogenic DI: Renal tubule resistance, such as lithium toxicity, hypercalcemia, hypokalemia.

Signs and Symptoms

Polyuria (3 to 20 L/day), polydipsia, dilute urine (specific gravity less than 1.005), elevated serum osmolality (>295), hypernatremia, dehydration, fatigue, weight loss.

Treatment

Central DI: Desmopressin (DDAVP) nasal spray, SC, or oral. Nephrogenic DI: Address underlying cause; thiazide diuretic paradoxically reduces urine output.

Nursing Interventions

Strict I&O, daily weights, monitor urine specific gravity and serum sodium, encourage fluid intake to match output if patient is alert. Educate on DDAVP administration. Contrast DI (LOW ADH, diluted urine) with SIADH (HIGH ADH, concentrated urine, low serum sodium).

NCLEX Relevance

High-yield cue: polyuria + low urine specific gravity + hypernatremia = DI.