In patients with hyponatremia, what physical findings differentiate syndrome of inappropriate antidiuretic hormone secretion (SIADH) from other hyponatremic states?

Updated: Aug 16, 2019
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
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After the identification of hyponatremia, the approach to the patient depends on the clinically assessed volume status. In SIADH, the patient is typically euvolemic and normotensive. Peripheral and pulmonary edema, dry mucous membranes, reduced skin turgor, and orthostatic hypotension are usually absent. Edema in a hyponatremic patient warrants consideration of another hyponatremic state, such as congestive heart failure (CHF), cirrhosis, or chronic kidney disease.

Prominent physical examination findings may be seen only in severe or rapid-onset hyponatremia and can include the following:

  • Confusion
  • Disorientation
  • Delirium
  • Generalized muscle weakness
  • Myoclonus
  • Tremor
  • Asterixis
  • Hyporeflexia
  • Ataxia
  • Dysarthria
  • Cheyne-Stokes respiration
  • Pathologic reflexes
  • Generalized seizures
  • Coma

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