Final answer:
In a client with adrenal insufficiency, a nurse should expect to find symptoms such as hyponatremia and not hypernatremia, making a decreased serum sodium level the likely finding. Signs like moon face and weight gain are associated with Cushing's syndrome, which is not the case in adrenal insufficiency.
Step-by-step explanation:
A client with adrenal insufficiency, also known as Addison's disease, typically presents with a number of symptoms resulting from the hyposecretion of corticosteroids. These symptoms include hyponatremia (low blood sodium levels), hypotension (low blood pressure), hyperkalemia (high blood potassium levels), hypoglycemia (low blood sugar levels), as well as non-specific symptoms such as weight loss, fatigue, and anemia.
Therefore, of the options provided, the finding a nurse should expect when assessing a client with adrenal insufficiency would most likely be hyponatremia, represented by a decreased serum sodium level. A serum sodium of 150 mEq/L, mentioned as option D, is indicative of hypernatremia, which associates with the opposite condition of hyperfunctioning adrenal cortex or Cushing's syndrome. The correct serum findings in adrenal insufficiency would be lower than normal sodium levels, which are typically less than 136 mEq/L.