Abstract

In reading the article “Addisonian Crisis Precipitated by Thyroxine Therapy: A Complication of Type 2 Autoimmune Polyglandular Syndrome,”¹ I was reminded of Dr. John Eager Howard’s warning to us some 35 years ago, when I was a resident at Union Memorial Hospital in Baltimore, about the dangers of thyroid replacement in long-standing hypothyroidism. Since thyroxine is needed to hydroxylate cortisone—thereby enabling the kidney to convert it to a glucronide and excrete it—the serum level of cortisone may fall precipitously with the institution of thyroid therapy, the “asleep” adrenals failing to respond. We were told to be sure the patient received a physiologic dose of cortisone for the first 6 weeks of thyroid replacement. This was apparently well-known in the “dark ages” of the 1960s and 1970s, before the Internet replaced the library for literature searches.