Many patients with underactive thyroid glands receive either too much or too little thyroid replacement therapy, putting them at risk for drug-related injuries, so-called adverse drug events (ADEs). Monitoring of thyroid replacement therapy, levothyroxine, could prevent or reduce the consequences of ADEs. However, a recent study found that only half of outpatients taking levothyroxine received the recommended monitoring during 1 year of followup, and levothyroxine-related ADEs were more frequent in patients with lower quality monitoring.
In the study, which was supported in part by the Agency for Healthcare Research and Quality (HS11169 and HS11534), Henry T. Stelfox, M.D., of Brigham and Women's Hospital and Harvard Medical School, and his colleagues reviewed the medical charts of 400 outpatients who received levothyroxine therapy between January 2000 and January 2001 at one hospital. Overall, 12 patients experienced levothyroxine-related ADEs. Five patients experienced temporary disability: depression (three), unstable angina (one), and atrial fibrillation (one). Seven patients had symptoms such as heart palpitations, weight loss, headaches, fatigue, and cold intolerance. Nine of the 12 ADEs were considered preventable.
Overall, 56 percent of the patients prescribed levothyroxine received the minimal recommended monitoring. Patients who received the recommended monitoring had fewer levothyroxine-related ADEs (1 vs. 6 percent) than those who did not. The incidence of levothyroxine-related ADEs was higher among Hispanics (14 percent) and blacks (4 percent) than among whites (2 percent) and among patients whose primary language was not English (20 percent) compared with English-dominant patients (3 percent).
For more details, see "An evaluation of the adequacy of outpatient monitoring of thyroid replacement therapy," by Dr. Stelfox, Sofia B. Ahmed, M.D., Julie Fiskio, and David W. Bates, M.D., M.Sc., in the November 2004 Journal of Evaluation in Clinical Practice 10(4), p. 525-530.
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