Increased levothyroxine requirements in critically ill patients with hypothyroidism

R. Imberti, M. Ferrari, R. Albertini, V. Rizzo, C. Tinelli

Research output: Contribution to journalArticlepeer-review

Abstract

Aim. An increased thyroxine requirement has been described in hypothyroid patients who have chronic gastritis as well as in patients who are treated with drugs that modify the acidic environment of the stomach. Patients with acute critical illnesses are generally treated with calorically dense enteral solutions and antacids, both of which influence the gastric acidic environment. In this study, we evaluated levothyroxine (L-thyroxine) requirements in hypothyroid patients admitted to our ICU. Methods. The medical records of nine patients with pre-existing hypothyroidism who did not have gastrointestinal diseases and who were admitted to our ICU between 2003 and 2008 were retrospectively reviewed. Serum TSH, FT 4, and FT 3 levels were measured at the time of admission and every four to eight days thereafter. After the second measurement of these parameters, patients' L-thyroxine doses were adjusted to maintain their TSH concentrations at baseline levels. Results. At the time of ICU admission, the median [interquartile range] TSH, FT 4, and FT 3 values of the included patients were 1.52 [0.79-3.8] mU/L, 6.5 [4.9-9.3] pg/mL, and 1.0 [4 levels decreased significantly. To restore patients' TSH levels to those at the time of admission, the L-thyroxine dose was increased in 8/9 patients by an average of 54.4±31.6% (P=0.001). At the time of ICU discharge, patients' TSH and FT 4 levels had returned to near their levels at the time of admission. All patients' serum FT 3 levels remained low throughout the entire duration of their ICU stay. Conclusion. To maintain TSH levels in the normal range, it may be necessary to increase the L-thyroxine dose of critically ill patients with hypothyroidism. Our findings also suggest that during the first several days of a critical illness, the hypothalamic-pituitary-thyroid axis is not suppressed in hypothyroid patients.

Original languageEnglish
Pages (from-to)500-503
Number of pages4
JournalMinerva Anestesiologica
Volume76
Issue number7
Publication statusPublished - Jul 2010

Keywords

  • Critical illness
  • Euthyroid sick syndrome
  • Hypothyroidism
  • Levo-thyroxine

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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