Etiology

1. Central diabetes insipidus (CDI)

2. Nephrogenic diabetes insipidus (NDI)

Central diabetes insipidus

• caused by insufficient or absent hypothalamic synthesis or secretion of antidiuretic hormone (ADH) from the posterior pituitary

• Primary (∼ ⅓ of cases)

  • Most cases are idiopathic.

  • The hereditary form is rare.

  • Autoimmune etiology of primary CDI has been suggested [2][3]

• Secondary (∼ ⅔ of cases)

  • Brain tumors (especially craniopharyngioma) and cerebral metastasis (most common: lung cancer and leukemia/lymphoma)

  • Neurosurgery: usually after the removal of large adenomas

  • Traumatic brain injury, pituitary bleeding, subarachnoid hemorrhage

  • Pituitary ischemia (e.g., Sheehan syndrome, ischemic stroke)

  • Infection (e.g., meningitis)

• Rare: caused by defective ADH receptors in the distal tubules and collecting ducts

• Types

  • Hereditary (mutation in ADH receptor): very rare

  • Acquired

    • Adverse effect of medications (lithium, demeclocycline)

    • Hypokalemia, hypercalcemia

    • Renal disease (e.g., autosomal dominant polycystic kidney disease, renal amyloidosis)

    • Pregnancy

NDI is a result of drug interference with the renal action of ADH.

Both lower responsiveness to ADH and sodium reabsorption.

Due to transient ADH resistance in the 2nd half of pregnancy; called gestational diabetes insipidus