Endocrine Abstracts

Background: It is well documented that some patients with hypothyroidism continue to be symptomatic despite normalisation of TSH levels with T4 mono-therapy. The Royal College of Physicians 2008 statement recommends that T4 alone should be used for the treatment of hypothyroidism with no recommendation for additional T3 therapy. However, the Internet has many reports of symptomatic benefit on combination therapy and patients may present to the outpatient clinic requesting T3 therapy. We reviewed the case-notes of those patients in our local population whom had symptoms of hypothyroidism despite normalisation of TSH with T4 alone and went on to try combination T4/T3 therapy.

Results: 12 patient notes were reviewed: 1 male, 11 female, mean age 48.7 ± 10.2 years. Causes of hypothyroidism were primary hypothyroidism (6), thyroidectomy (3), thyroiditis (2) and secondary hypothyroidism (1). A variety of doses of combination therapy were prescribed from 100mcg T4 and 10mCg T3, through to lone T3 180mcg/day. 7 patients had some symptomatic benefit, 1 patient had an initial benefit but subsequently stopped it due to side effects. Combination therapy had no symptomatic benefit in 4 patients. 2 of the patients on long-term combination therapy experienced palpitations.

Conclusion: This data shows that the majority of patients (58%) reported symptomatic benefit and preferred to remain on combination therapy despite the possible risk of complications. The objective measurement of symptomatic benefit in these individuals is difficult to evaluate and observed benefit may be due to induced throtoxicosis rather than T3 therapy. Long-term combination therapy creates new challenges of management including monitoring of thyroid function tests and evaluating possible complications of T3 therapy. We would advocate careful discussion of the risks and benefits of combination therapy, in those patients that request it, and a low threshold for withdrawing therapy in any experiencing symptoms of thyroid hormone toxicity.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.