A nurse is providing teaching to a client who has chronic rheumatoid arthritis and a new prescription for hydroxychloroquine. The nurse should instruct the client to obtain which of the following diagnostic studies routinely?

Furosemide is a loop diuretic commonly used to treat fluid volume excess by promoting diuresis. One of the expected outcomes of furosemide administration is an increased urinary output as excess fluid is eliminated from the body. Therefore, if the medication has been effective, the nurse would expect to see an increased urinary output as a result of the diuretic effect.

Increased respiratory rate (B) is not an expected outcome of furosemide administration. It may occur in some cases due to increased fluid elimination and potential electrolyte imbalances, but it is not the primary indicator of the medication's effectiveness.

Decreased blood pressure (C) is a possible outcome of furosemide administration due to the diuretic effect and subsequent reduction in fluid volume. However, it is not the most specific indicator of the medication's effectiveness in this case.

Increased pulse (D) is not a typical finding associated with the effectiveness of furosemide. In fact, furosemide can sometimes cause a decrease in heart rate due to its impact on fluid and electrolyte balance.

The nurse should report a creatinine level of 2 mg/dl to the provider as a potential adverse effect of captopril. Captopril is an angiotensin-converting enzyme (ACE) inhibitor commonly used to treat congestive heart failure and hypertension. One of the side effects of ACE inhibitors, including captopril, is the potential to cause kidney problems, leading to an increase in serum creatinine levels.

An increase in serum creatinine may indicate impaired kidney function, and it is essential to monitor kidney function regularly in clients taking ACE inhibitors. Elevated creatinine levels can suggest reduced glomerular filtration rate (GFR) and impaired kidney function, which may require adjustments in medication dosage or further evaluation and management.

Let's go through the other options:

A. Absolute neutrophil count (ANC) 4.000/ mm^3: An absolute neutrophil count of 4.000/ mm^3 is within the normal range, so it is not an adverse effect of captopril that requires immediate reporting.

B. Brain natriuretic peptide (BNP) 90 ng/L: A brain natriuretic peptide (BNP) level of 90 ng/L is used to assess heart failure severity. While BNP levels can be helpful in managing congestive heart failure, a BNP level of 90 ng/L is not an adverse effect of captopril that requires immediate reporting.

C. Sodium 140 mEq/l: A sodium level of 140 mEq/L is within the normal range, so it is not an adverse effect of captopril that requires immediate reporting.