A 49 yrs old lady was referred to us as her primary hypothyroidism deteriorated after exacerbation of her ulcerative colitis (UC). She also has coeliac disease. Although on levothyroxine (oral T4) 175 mcg, her thyroid stimulating hormone (TSH) remained above 40 mU/L (0.355.00 mU/L), and free thyroxine (FT4) was <5.15 pmol/L (9.020.0 pmol/L). A step wise increase of oral T4 to 900 mcg proved no benefit. Changing oral T4 tablets to syrup and addition of low dose of liothyronine (oral T3) 20 mcg also made no difference. A trial low dose (20 mcg) of intravenous T3 injection showed improvement clinically while her TSH level remained elevated. Hence, a combination therapy of oral T4 (700 mcg) and high dose of oral T3 (60 mcgs) was attempted. She made remarkable improvement symptomatically and biochemically, her TSH was reduced to 6.6 mU/L and FT4 increased to 8.5 pmol/L. She was further maintained only on oral T3 (40 mcg) daily. Unfortunately, she later had a flare up of her UC during which her TSH increased to 40 mU/L while her FT4 decreased to <5.5 pmol/L. An increase in her oral T3(60 mcg) and T4 (300 mcg) initially, followed by a subsequent reduction of her oral T3 (40 mcg) and oral T4 (200 mcg) managed to maintain her TSH at <0.05 mU/L and FT4 at 13.0 pmol/L. With her UC in remission, her oral T3 is maintained at 40 mcg while her oral T4 is reduced to 100 mcg.
Conclusion: High dose of oral T3 (40 mcg) therapy may be an effective treatment in patients suffering from inflammatory bowel disease (IBD) and/or coeliac disease if they do not respond to high dose of oral T4. During a flare up of IBD, a higher dosage of oral T3 (60 mcg) might even be required.
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.