A nurse is assessing a client who had a craniotomy and has developed syndrome of inappropriate antidiuretic hormone (SIADH). Which of the following manifestations should the nurse anticipate?

Choice A reason: Increased hunger is not associated with SIADH, which involves excessive antidiuretic hormone causing water retention. Hunger is more related to metabolic or hypothalamic disorders. SIADH affects fluid and electrolyte balance, primarily leading to hyponatremia, not appetite changes, making this choice incorrect. Choice B reason: Hypernatremia is not expected in SIADH. Excessive antidiuretic hormone causes water retention, diluting serum sodium and leading to hyponatremia. Hypernatremia occurs in conditions like diabetes insipidus with water loss, not SIADH’s water excess, making this an incorrect manifestation. Choice C reason: Hyponatremia is a hallmark of SIADH, as excessive antidiuretic hormone increases renal water reabsorption, diluting serum sodium (below 135 mEq/L). This can cause neurological symptoms like confusion, especially post-craniotomy, where brain injury may trigger ADH release, making this the expected finding. Choice D reason: Weight loss is not typical in SIADH, which causes water retention, leading to weight gain from fluid accumulation. Weight loss occurs in conditions like diabetes insipidus with water loss, not SIADH’s fluid retention, making this an incorrect manifestation for the condition.