A client who has active tuberculosis and is taking rifampin reports that his urine and sweat have developed a red-orange tinge. Which of the following actions should the nurse take?

The correct answer is D: Document this as an expected finding. Rifampin, an antibiotic used to treat tuberculosis, can cause red-orange discoloration of urine, sweat, and other bodily fluids as a harmless side effect. This is a well-known and expected consequence of rifampin therapy and does not indicate any serious problem. In this case, the nurse should document this finding in the client's medical record to ensure accurate documentation of the side effect. Increasing fluid intake (choice A) is not necessary for this specific side effect. Dialysis (choice B) is not indicated as the red-orange tinge is not a sign of kidney dysfunction. Checking liver function tests (choice C) is not needed as the discoloration is not related to liver function. By choosing option D, the nurse demonstrates understanding of the expected side effect of rifampin and takes appropriate action to document it.