Urea

Urea: A nitrogen-containing substance normally cleared from the blood by the kidney into the urine. Diseases that compromise the function of the kidney often lead to increased blood levels of urea, as measured by the blood urea nitrogen (BUN) test. Urea is of major historical significance.
   Urea is used to treat dry/rough skin conditions (e.g., eczema, psoriasis, corns, callus) and some nail problems (e.g., ingrown nails). It may also be used to help remove dead tissue in some wounds to help wound healing. Urea is known as a keratolytic.