What would be the appropriate nursing diagnosis for this client?
A client recently diagnosed with syndrome of inappropriate antidiuretic hormone (SIADH) complains of headache, weight gain, and nausea.

Excess fluid volume related to increased water retention

The client exhibits signs of excess fluid volume. Syndrome of inappropriate antidiuretic hormone (SIADH) is the release of excess ADH by the pituitary gland, which results in hypervolemic hyponatremia and clinical manifestations of headache, weight gain, and nausea.