According to Dictionary.com, uraemia, or uremia, is when the waste products that are normally expelled through the urine, such as urea, are backing up into the blood. It is from the Greek words "ouron," meaning urine, and "haima," meaning blood.
Dictionary.com also states that uraemia can cause headaches and vomiting, often severe. Wikipedia says that uraemia often accompanies kidney failure and has symptoms like fatigue, weakness, nausea, cramps, itching and hiccups. The diagnostic tests given are typically urine tests, blood tests, radioisotope tests, and platelet and coagulation tests. Having urinary waste products in the blood that have not yet caused symptoms is called azotemia.