Endocrine Abstracts

We report a case of a female patient who presented aged 37yr with tiredness, weight gain and oligomenorrhea. Biochemically she was diagnosed with primary hypothyroidism with a TSH 10.9 mu/L and free-T4 8.2 pmol/L (10.5–22.0); she was commenced onto Thyroxine 50 mcg once a day (OD). Six months later her thyroid function tests improved with a TSH 2.2 mu/L and free-T4 13.0 pmol/L, however she felt her symptoms had worsened. The dose of thyroxine was increased to 75 mcg OD. However, despite the free-T4 rising to 19.7 pmol/L with a TSH of 0.86 mu/L the patient felt very unwell and did not tolerate this dose. In the intervening 3 years the thyroxine dose remained between 25 mcg–50 mcg OD, but she still had been complaining of lethargy that was severely affecting her work, social and family life. She presented to our centre with a multitude of symptoms on Thyroxine 25 mcg OD. Investigations revealed a TSH 3.0 mu/L (0.4–4.0), free-T4 11.9 pmol/L (10.3–24.5) and free-T3 3.2 pmol/L (2.3–6.5). Other causes of tiredness were investigated; she had a 9am cortisol 447 nmol/L, 25-OH vitamin-D 90 nmol/L (51–163), negative coeliac screen and a fasting glucose 4.2 mmol/L. She was given a trial of Tertroxin (T3) initially at 20 mcg on alternate days which was increased to 20 mcg OD, resulting in a TSH of 1.5 mu/L. Her symptoms dramatically improved and she commented, “my life has returned back to me for the first time in 10 years.” Although investigators have disputed the benefit of combination T4/T3 therapy (1), there is a subgroup of patients that benefit from this treatment (2,3). Our patient could not tolerate thyroxine, despite her normal TSH, so T3 was the only available option. T3 therapy dramatically improved her general wellbeing and “gave her life back”. T3 should be considered in patients with primary hypothyroidism whose symptoms do not respond to thyroxine treatment.

References

1. Grozinsky-Glasberg S et al. Thyroxine-triiodothyronine combination therapy versus thyroxine monotherapy for clinical hypothyroidism: meta-analysis of randomized controlled trials. JCEM 2006;91:2592–2599.

2. Bunevicius R et al. Effects of thyroxine as compared with thyroxine plus triiodothyronine in patients with hypothyroidism. NEJM 1999;340:424–429.

3. Nygaard B et al. Effect of combination therapy with thyroxine (T4) and 3,5,3′-triiodothyroxine versus T4 monotherapy in patients with hypothyroidism, a double-blind, randomised cross-over study. EJE 2009;161:895–902.

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.