This ECG is from a 22 year old female with chronic renal failure. Her serum potassium level was 6.5 mM and her serum calcium was 7.0 mg/dl. The tracing shows changes consistent with both hyperpotassemia and hypocalcemia, There is prolongation of the ST segment seen best in the frontal plane leads and in leads V4-V6. This is a manifestation of the hypocalcemia. The T wave is symmetrical, tented and peaked. This reflects the mild hyperpotassemia. An electrocardiogram with these features is pathognomonic of chronic renal failure.