A nurse is providing teaching to a client who has a new prescription for warfarin. Which of the following findings requires a referral for further care?

Choice A reason: Starting work in a parking garage while on warfarin does not inherently indicate a need for referral unless specific risks (e.g., injury prone to bleeding) are present. Without additional concerns, this situation is routine, making it incorrect for requiring further care. Choice B reason: Increased urinary frequency with bumetanide, a diuretic, is an expected side effect, not requiring referral unless severe or accompanied by electrolyte imbalances. This is a normal response, so it does not warrant further care, making it incorrect. Choice C reason: An induration 48 hours after a Mantoux test suggests a positive tuberculosis result, requiring referral for chest X-ray and further evaluation. This finding indicates potential latent or active TB, a significant health concern, making it the correct choice for referral. Choice D reason: Being 1 day postoperative after knee replacement is expected, with routine monitoring for complications like infection or thrombosis. Without specific issues, this does not require referral beyond standard postoperative care, making it incorrect.