The rarity of shortening of the Q-T interval in patients with hypercalcemia.
Shortening of the Q-T interval on the 12-lead ECG is often attributed to hypercalcemia and is sought in critically ill patients to confirm suspected hypercalcemia. In our experience, hypercalcemia of greater than 13 mg/dl (3.25 mM/L) was unaccompanied by ECG changes. The records of the Brooklyn VA Medical Center for a 3-year period were reviewed and yielded 125 patients with hypercalcemia. Of these, 48 (38%) had a serum calcium of greater than 13 mg/dl. Of these 48, 10 (21%) had an ECG recorded at the same time. The mean serum calcium in these patients was 13.6 mg/dl (3.40 mM/L). None had an abnormally short Q-T interval when the interval was corrected for heart rate (Q-Tc). The ionized calcium was estimated and yielded a mean of 2.26 mM/L (normal range = 0.94-1.33 mM/L). No cause for overestimation of ionized calcium was apparent. It is concluded that the Q-T interval is not a useful clue to the presence of hypercalcemia.
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D006934:Hypercalcemia / Q000175:diagnosis* / Q000209:etiology; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood; D012189:Retrospective Studies