PRIMARY ADRENAL INSUFFICIENCY DURING LENVATINIB OR VANDETANIB AND IMPROVEMENT OF FATIGUE AFTER CORTISONE ACETATE THERAPY.

Context Two tyrosine kinase inhibitors (TKIs), lenvatinib and vandetanib, are often used to treat advanced radioiodine-refractory differentiated thyroid cancer (RAI-R DTC) and medullary thyroid cancer (MTC), respectively. Fatigue is a common adverse event during treatment with these and other TKIs and a common cause of drug discontinuation or dosage reduction.