T wave lability: a clue for separating the good from the bad, when ugly.

Non-specific T wave abnormalities have challenged both the clinician and the insurance medical director for decades. Distinction between pathologic and physiologic T wave changes often requires costly and time-consuming diagnostic studies. The literature is reviewed on the subject of T wave manipulation by the oral administration of both potassium and glucose, introducing the concept of T wave lability. Based on this concept, a simple technique is suggested which, in many cases, can safely, expeditiously and inexpensively distinguish between organic and functional T wave changes. When employed in the investigation of asymptomatic insurance applicants with unexplained T wave abnormalities but no known cardiovascular or renal disease, this technique appears to be sufficiently reliable to classify the risk posed by non-specific T wave changes without resorting to a sophisticated, lengthy and costly cardiovascular investigation.