title: Benefit of combined triiodothyronine (LT(3)) and thyroxine (LT(4)) treatment in athyreotic patients unresponsive to LT(4) alone.
abstract: Despite some reports, the usefulness of levothyroxine (LT(4)) and levotriiodothyronine (LT(3)) combination therapy in hypothyroidism remains controversial. The objective of this paper is to study a benefit of additional LT(3) in athyreotic patients who failed to normalize TSH on LT(4) alone even with hyperthyroid serum T(4) values. In a survey of 200 athyreotic patients treated between 2006 and 2009, about 7% failed to normalize serum TSH levels following treatment with LT(4), though serum T(4) values in the hyperthyroid range were achieved. These patients (characterized by serum T(4)≥160 nmol/L and TSH≥5.0 mIU/L), were additionally treated with 10 μg b. i. d LT(3). LT(3) and LT(4) combination therapy resulted in decreased serum TSH levels into the normal range (12.8 vs. 1.22 mIU/L; p<0.01) and reduced LT(4) dose (153.3 vs. 117.5 μg; p<0.01) required for normalization of serum T(4) values (170.6 vs. 123.3 nmol/L; p<0.01). Serum T(3) values were higher (1.3 vs. 2.26 nmol/L; p<0.01) than those during monotherapy with LT(4). Our results indicate a subpopulation of athyreotic patients that could significantly benefit from combined LT(4) + LT(3) therapy in restoring normal TSH and thyroid hormone patterns. Further research should be undertaken to provide a genetic basis for these findings.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Sisters of Mercy University Hospital Center, Zagreb, Croatia.
authors.forename: D
authors.initials: D
authors.lastname: Solter
authors.forename: M
authors.initials: M
authors.lastname: Solter
mesh_terms: D000328:Adult; D004338:Drug Combinations; D005260:Female; D005500:Follow-Up Studies; D020249:Hormone Replacement Therapy / Q000379:methods; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D013974:Thyroxine / Q000008:administration & dosage*; D017211:Treatment Failure; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000008:administration & dosage*
chemical_list: D004338:Drug Combinations; D014284:Triiodothyronine; D013974:Thyroxine