The evaluation of the syndrome of inappropriate antidiuretic hormone begins with a history and physical examination.

Physical findings in someone with the syndrome of inappropriate ADH may include:

• Decreased deep tendon reflexes
• Weakness or fatigue
• Confusion

Tests are necessary to make the diagnosis of the syndrome of inappropriate ADH. Usually, a low concentration of sodium in the bloodstream is discovered during an evaluation for another condition.

Tests that may be used to evaluate the syndrome of inappropriate ADH include:

• Urinalysis
• Serum sodium level
• Plasma levels of antidiuretic hormone