Coupon Accepted Successfully!



  1. Carcinomas: Lung, Duodenum, Pancreas, Ovary, Bladder, ureter
  2. Head trauma (closed and penetrating)
  3. Infections: Pneumonia, bacterial or viral, Abscess, lung or brain, Tuberculosis, lung or brain, Meningitis, bacterial or viral, AIDS
  4. Vascular: . CVA (SAH)
  5. Neurologic: Guillain - Barre- syndrome, Multiple sclerosis
  6. Metabolic: Acute intermittent porphyrias
  7. Drugs (MCQ):
    1. Vasopressin or desmopressin,
    2. Chlorpropamide,
    3. Oxytocin,
    4. Vincristine,
    5. Carbamazepine,
    6. Nicotine,
    7. Phenothiazine,
    8. Cyclophosphamide,
    9. Tricyclic antidepressants,
    10. MAOI
    11. Serotonin reuptake inhibitor

Clinical features of SIADH

They are due to hyponatremia which are related to osmotic water shift. It lead to increase intra cellular fluid volume in the brain cell causing swelling of the brain cell which lead to cerebral edema. Patient may be asymptomatic, or may have convulsion (LQ 2012), Coma or death.

Laboratory features of SIADH

  1. Hyponatremia (serum sodium < 135 mEq/L)
  2. Inappropriately elevated urine osmolality (> 100 mosm/kg)
  3. Decreased serum osmolality (< 280 mosm/kg)
  4. B.U.N. and serum uric acid tends to fall because of plasma dilution and increased excretion of nitrogenous products.
  5. Serum potassium and Bicarbonate levels are normal in SIADH.
  6. Increase urinary sodium (More than 30 meq/lil
  7. Water loading test is done
Extra Edge Water loading test

In SIADH there is an abnormal water load test (i.e. inability to excrete at least 90% of a 20 ml/kg water load in 4 h and/or failure to dilute urine osmolality <100 mosm/kg), and there is plasma ADH levels inappropriately elevated relative to plasma osmolality.

Treatment of SIADH

  1. Standard first line therapy is water restriction.
  2. If more rapid correction of hyponatremia is desired, the fluid restriction can be supplemented with i. v. infusion of hypertonic saline (3%).
Important Points
  1. A rapid correction will produce central pontine myelinolysis which is an acute potentially fatal neurological syndrome characterized by quadriparesis, ataxia and abnormal extraocular movements.
  2. To prevent this complication the hypertonic saline should be infused slowly.

Treatment of Chronic SIADH

  1. Hyponatremia can be corrected by with
    1. Demeclocycline
    2. Conivaptan

Recent Advances Conivaptan is a new drug. It is a treatment option for hyponatremia in place of Demeclocycline. (Ref. Hari. 18th ed., Pg - 349, 828).


Certain conditions that interfere with laboratory tests of serum sodium concentration (may lead to an erroneously low measurement of sodium. This is called pseudohyponatremia).
  1. Hyperlipidemia
  2. Hyper paraproteinemia (Multiple myeloma)
  3. Severe hyperglycemia (DKA, NKHOC)


  1. It is a non-peptide inhibitor of antidiuretic hormone (vasopressin receptor antagonist).
  2. It is for hyponatremia (low blood sodium levels) caused by syndrome of inappropriate antidiuretic hormone (SIADH)
  3. Conivaptan inhibits two of the three subtypes of the vasopressin receptor (V1a and V2).
  4. Effectively, it causes iatrogenic nephrogenic diabetes insipidus.

Test Your Skills Now!
Take a Quiz now
Reviewer Name