ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 P380 | DOI: 10.1530/endoabs.63.P380

The Effect of Ramadan fasting on thyroid hormone levels in patients on levothyroxine treatment

Fatma Dilek Dellal1, Berna Ogmen2, Didem Ozdemir2, Fatma Neslihan Cuhaci2, Sefika Burcak Polat2, Reyhan Ersoy2 & Bekir Cakir2

1Endocrinology Department, Ataturk Training and Research Hospital, Ankara, Turkey; 2Faculty of Medicine, Endocrinology Clinic, Yildirim Beyazit University, Ankara, Turkey.

Aim: Contradictory results in limited number of studies were reported about the effects of Ramadan fasting on thyroid hormones. We aimed to evaluate the thyroid functions in Ramadan, and compare late evening or pre-sahour use of levothyroxine in patients being treated for hypothyroidism.

Methods: Patients taking levothyroxine for hypothyroidism who were seen in the last one week before Ramadan (8–15 May 2018) and had normal thyroid functions were recruited. Patients were offered to take levothyroxine at 22.30–23.00 pm before sleep (Group-1) or between 01:30 and 03:00 am at least 30 min before sahour (Group-2).

Results: Basal thyrotophin (TSH) was 2.01±1.05 μIU/ml and significantly increased at the end of Ramadan (3.09±3.38 μIU/ml, P=0.008). Free-triiodothyronine (FT3) decreased while free-thyroxine (fT4) increased (P<0.001, P=0.028). Eighteen patients were in Group-1 and 44 were in Group-2. There was unsignificant increase in TSH and FT4 in Group-1 (P=0.160, P=0.425), while both increased significantly in Group-2 (P=0.022, P=0.008). FT3 decreased in Group-1 and 2 (P=0.016, P<0.001). At the end of Ramadan, TSH increased in 39(%63.9), decreased in 22 (%36.1) and did not change in 1 patient. Anti-thyroid peroxidase antibody was positive in 65.5% of patients with increased TSH and in 35.3% of patients with decreased TSH (P=0.047).

Conclusion: Although mean TSH increased significantly,about one third of patients had lower TSH indicating for the need to evaluate every patient individually and follow closely during this month. Use of levothyroxine in late evening seems to maintain more stable thyroid hormones compared to pre-sahour. Clinical studies with larger sample sizes will be helpful to determine the optimal time for levothyroxine use during Ramadan.

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