To look for Myoglobin protein in Urine.Urine myoglobin levels reflect the degree of muscle injury and, since myoglobin is toxic to the kidneys, reflect the risk of kidney damage. This test measures a protein called myoglobin in your urine. The test can help find out if your muscle tissue has been injured. Myoglobin is found in your heart and skeletal muscles. There it captures oxygen that muscle cells use for energy.