Polyuria and Polydipsia: Causes Across Renal, Metabolic, and Endocrine Systems

Polyuria (excessive urine output) and polydipsia (excessive thirst) signal underlying disorders:

I. Renal Causes

• Diabetes insipidus: Central (ADH deficiency) or nephrogenic (renal ADH resistance).
• Chronic kidney disease: Polyuria often early sign.
• Acute tubular necrosis: Polyuria during recovery phase.
• Sickle cell anemia: Chronic renal involvement.

II. Metabolic Causes

• Hyperglycemia (diabetes mellitus): Osmotic diuresis from glucosuria.
• Hypercalcemia: Impairs urine concentrating ability.

III. Endocrine Causes

• Cushing’s syndrome: Cortisol excess affects renal function.
• Hyperthyroidism: Increased metabolism → polyuria.

IV. Other

• Psychogenic polydipsia: Compulsive water drinking.
• Medication-induced: Steroids, osmotic diuretics.
• BPH (men): Obstruction → polyuria.

Persistent symptoms require medical evaluation to identify and treat the root cause.