Q: I was hospitalized for kidney failure. I had a severely swollen arm, I.V. antibiotics were used and now my kidneys are functioning normally. I have purple blotches all over my trunk. These started shortly before the hospitalization, they are not fading and seem to be increasing. They are not thick and are neither painful. My last blood test showed normal kidney function. What is the cause of these purple blotches on my skin?

A:Purple blotches on the skin in renal failure suggest a blood platelet abnormality causing purpura. A complete blood cell count by a reliable pathology laboratory would demonstrate the abnormality. Other concerns would be collagen vascular disease causing vasculitis, or HIV infection with Kaposi sarcoma. Blood tests would make these diagnoses available to the physician who orders the appropriate panel of tests.