Mifepristone Increases Thyroid Hormone Requirements in Patients With Central Hypothyroidism

A Multicenter Study

Francisco J. Guarda; James Findling; Kevin C.J. Yuen; Maria Fleseriu; Lisa B. Nachtigall


J Endo Soc. 2019;3(9):1707-1714. 

In This Article



Consecutive patients (N = 5) with a diagnosis of CD and concomitant CH were selected for inclusion in this series from four different pituitary centers if they had an increase in levothyroxine dose requirement demonstrated during therapy with mifepristone.

Patients receiving mifepristone for hyperglycemia associated with ACTH-dependent hypercortisolemia were included if they had documented CH treated with levothyroxine prior to the initiation of mifepristone, laboratory data on thyroid function tests before and during therapy with mifepristone, and increased requirements of levothyroxine during treatment with mifepristone. Increased requirement was defined as a decrease in FT4 to low or borderline low levels despite a stable or even increasing levothyroxine dose. Exclusion criteria included baseline thyroid test results unavailable for analysis and/or primary (rather than central) hypothyroidism documented prior to mifepristone initiation.


A longitudinal analysis was performed with FT4 levels measured at consecutive outpatient care visits over a period of up to 54 months. Each patient was evaluated by a neuroendocrinologist at the respective centers and, if criteria were met, clinical records were reviewed and data recorded following Health Insurance Portability and Accountability Act regulations. Informed consent was waived as retrospective database have been approved by institutional review boards.


FT4 assays were assessed by standard techniques at each center, with normal values for each assay stated in the results section: at Massachusetts General Hospital and Medical College of Wisconsin, Roche Diagnostics Chemiluminescent assay;[14] at Oregon Health and Science University, Siemens Vista Chemiluminescent Immunoassay;[15] at St. Joseph's Hospital and Medical Center, Abbott Laboratories Chemiluminescent Microparticle Immunoassay.[16] rT3 was measured at Mayo Clinic, using liquid chromatography-tandem mass spectrometry (LC-MS/MS).


Mean, range, and standard deviations are reported for normally distributed data. Median and interquartile range (IQR) are reported for nonnormally distributed data. Values are shown as the median and IQR unless otherwise indicated.