Definition
- Diabetes insipidus (DI) is a disease characterized by excretion of a large volume of hypotonic urine that is devoid of taste from dissolved solutes that is caused by the absence of or inadequate response to vasopressin or antidiuretic hormone (ADH)
Pathophysiologic Mechanisms
Central (Hypothalamic or Neurohypophyseal) DI
- Inability to secrete and produce vasopressin in the neurohypophyseal system
- Damage to the pituitary gland and hypothalamus may be due to diseases, head injuries, neurosurgery, infection or genetic or autoimmune disorders
Nephrogenic DI
- There is inappropriate renal response to vasopressin
- Kidney function may be impaired by drugs and by chronic disorders like polycystic kidney disease, sickle cell disease, kidney failure, partial ureteral block, hypokalemia, hypocalcemia, low protein diet and genetic disorders
Primary Polydipsia
- Abnormal increase in fluid intake
Other
- Transient DI of pregnancy due to increased metabolism of vasopressin
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Central DI
- Idiopathic
- Familial
- Autosomal dominant
- Cerebral malformations
- DI, diabetes mellitus (DM) and optic atrophy deafness (DIDMOAD) syndrome
Nephrogenic DI
- Familial
- Genetic: Autosomal recessive or X-linked recessive inheritance
- Osmotic diuresis eg DM
- Metabolic eg hypercalcemia, hypokalemia
- Trauma, tumor, aneurysm, hemorrhage
- Idiopathic
- Granuloma eg tuberculosis (TB), sarcoidosis, histiocytosis
- Infections eg cytomegalovirus (CMV), toxoplasmosis, meningitis
- Drugs eg aminoglycosides, Amphotericin B, Cisplatin, Colchicine, Demeclocycline, Lithium, Methoxyflurane, Vinblastine
Primary Polydipsia
- Habitual, compulsive
- Psychological disturbances
- Schizophrenia, mania, obsessive-compulsive disorder
- Drugs eg Lithium, Carbamazepine, Phenothiazine
- Hypothalamic lesion
- May be iatrogenic/healthcare worker-induced (recommendation of a high-fluid intake)
- Chronic renal disease
- Post-obstructive uropathy
- Renal medulla solute washout
Signs and Symptoms
Adults
- Polyuria
- Polydipsia
- Nocturia (3-18 L)
- Hydronephrosis
- Bladder enlargement
- Highly variable urine output
- Predilection for drinking cold liquids
Infants and Children
- Poor feeding
- Failure to thrive
- Irritability
- Blunted appetite
- Nocturia
- Neonates suck strongly during feeding but may vomit immediately after that
- Constipation, hard stools
- Slow growth