MYXEDEMA COMA - RESPONSE OF THYROID-HORMONES WITH ORAL AND INTRAVENOUS HIGH-DOSE L-THYROXINE TREATMENT

Myxoedema coma is a medical emergency with high mortality. In this study, clinical response and plasma variations of thyroid hormones were analysed in 7 patients, 6 presenting with myxoedema coma and one with myxoedema ileus. These patients were treated with intravenous or oral 1-thyroxine (1-T4). 1000-mu 1-T4 iv were administered in two patients. Within 3 h, plasma T4 and triiodothyronine (T3) reached a peak upper normal range, then diminished slowly during 5-9 days. The 5 remaining patients were treated with 500-mu-g 1-T4 po on the first day, then 100-mu-g 1-T4 daily by mouth. Plasma T4 and T3 increased slowly, remaining in hypothyroid range but clinical response (assessed on mental status, pulse rate and body temperature) occurred within 24-72 h. Cortisone therapy was used in 3 patients. Two patients died of myocardial infarction, or septicemia, one while receiving cortisone therapy and i.v. 1-T4, another one treated only by oral 1-T4. This study suggests: 1) oral absorption of 1-T4 is variable, but clinical response occurs quickly even in myxoedema ileus; 2) the intravenous route involves high peaks of plasma T4 and T3; 3) peripheral conversion of T4 to T3 allows gradually T3 delivery to organ systems, even if only 1-T4 is used and 4) initial and daily dosage determinations need further studies.