This blood test is often ordered during a patient's yearly physical exam to check on how well their kidneys are functioning. This test may also be ordered when a patient is acutely ill or when a doctor suspects kidney problems. The following symptoms often lead to a doctor performing a creatinine blood test: fatigue, loss of appetite, difficulty sleeping, concentration problems, decreased output of urine, trouble urinating, urinating more often, high blood pressure, pain in the mid-back, brown or foamy urine, blood in the urine, and swelling of the eyes, ankles, face, thighs, abdomen or wrists. These symptoms often indicate kidney dysfunction therefore this blood test will be performed to diagnose the problem or to rule out kidney dysfunction as the cause.