Letter to Editor about "Hypothyroidism and Ramadan Fasting"

Document Type : Letter to the Editor


Research Institute for Endocrine Sciences Shahid Beheshti University of Medical Sciences, Tehran, Iran


We have found that refeeding with a mixed diet or with carbohydrate, even though hypocaloric, reverses the changes in serum T3 and rT3 caused by fasting. This finding complements those of other studies that demonstrate the importance of dietary carbohydrate in the modulation of serum T3. Alteration in various parameters during Islamic (Ramadan) fasting is completely different from experimental fasting. From a physiological standpoint, Islamic fasting provides a unique model of intermittent daily fasting for one month. It is also distinct from regular voluntary or experimental fasting in that the faster does not drink during fasting hours. Therefore, one may assume that physiological changes occurring during Islamic fasting would differ from those observed during an experimental fast. No significant alterations in serum concentrations of T4, T3, TSH, and TSH   response to intravenous injection of TRH were found to occur in fasting males during Ramadan. In women, serum T4 and T3 concentrations may decrease in the last days of Ramadan however, the being mainly due to alterations in protein binding, as free thyroid indices remain unchanged (8, 9). A small increase in serum T4 in the last days of Ramadan has been reported by some studies, but not substantiated by others (7-10, 11). Serum T3 may decrease in pre-menarche girls without increase in serum TSH. 


  1. Hadjzadeh M, Pakdel R, Hayatdavoudi P Nematy M, Hypothyroidism and Ramadan Fasting. J Fasting Health 2014; 2: 80-83.

  2. Portnay GI, O'Brian JT, Bush J, Vagenakis AG, Azizi F, Arky RA, Ingbar SH, Braverman LE. The effect of starvation on the concentration and binding of thyroxine and triiodothyronine in serum and on the response to TRH. J Clin Endocrinol Metab 1974; 39: 191-4.

  3. Spaulding SW, Chopra IJ, Sherwin RS, Lyall SS. Effect of caloric restriction and dietary composition of serum T3 and reverse T3 in man. J Clin Endocrinol Metab 1976; 42: 197- 200.

  4. Carlson HE, Drenick EJ, Chopra IJ, Hershman JM. Alterations in basal and TRH-stimulated serum levels of thyrotropin, prolactin, and thyroid hormones in starved obese men. J Clin Endocrinol Metab 1977; 45: 707-13.

  5. Azizi F. Effect of dietary composition on fasting-induced changes in serum thyroid hormones and thyrotropin. Metabolism 1978; 27: 935-42.

  6. Azizi F. Islamic Fasting and Health. Ann Nutr Metab 2010; 56: 273-282.

  7. Azizi F, Amir Rasouli H. Evaluation of certain hormones and blood constituents during Islamic fasting month. J Med Assoc Thailand 1986; 69: (Suppl): 57A

  8. Sulimani RA. Effect of Ramadan fasting on thyroid function in healthy male indi viduals. Nutr Res 1988; 8: 549-552.

  9. Azizi F, Nafarabadi M, Amini M. Serum thyroid hormone concentration in healthy women during month of Ramadan. Emirates Med J 1994; 12: 140-3.

  10. Ahmadinejad Z, Ziaee V, Rezaee M, Yarmohammadi Y, Shaikh H, et al. The effect of Ramadan fasting on thyroid hormone profile: A cohort study. Pakistan J of Bilog Sciences 2006; 9: 1999-2002.

  11. Sajid KM, Akhtar M, Malik GQ. Ramadan fasting and thyroid hormone profile. J Pak Med Assoc 1991; 41: 213-6.

  12. Bahrayni SH, Vakili R, Nematy M, Norouzy A, Hashemy I, Ebrahimi M, et al. The effect of Ramadan Fasting on thyroid hormones in 9- 13 years old pre-menarche girls. J Fasting Health 2013; 1: 46-52.

  13. Karoli R, Fatima J, Chandra A, Mishra PP. Levothyroxine replacement and Ramadan fasting. Indian J Endocrinol Metab 2013; 17: 318-19.

  14. Campbell NR, Hasinoff BB, Stalts H, Rao B, Wong NC. Ferrous sulfate reduces thyroxine efficacy in patients with hypothyroidism. Ann Intern Med 1992; 117:1010-3.

  15. Sherman SI, Tielens ET, Ladenson PW.Sucralfate causes malabsorption of Lthyroxine. Am J Med 1994; 96:531-5.

  16. Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. JAMA 2000; 283:2822-5.

  17. Siraj ES, Gupta MK, Reddy SS. Raloxifene causing malabsorption of levothyroxine. Arch Intern Med 2003; 163:1367-70.

  18. Liel Y, Harman-Boehm I, Shany S. Evidence for a clinically important adverse effect of fiber-enriched diet on the bioavailability of levothyroxine in adult hypo- thyroid patients. J Clin Endocrinol Metab 1996; 81: 857-7.

  19. Benvenga S, Bartolone L, Pappalardo MA, Russo A, Lapa D, Giorgianni G, et al. Alteredintestinal absorption of L-thyroxine caused by coffee. Thyroid 2008; 18: 293-301.

  20. Bach-Huynh TG, Nayak B, Loh J, Soldin S,Jonklaas J. Timing of levothyroxine administration affects serum thyrotropin concentration. J Clin Endocrinol Metab 2009; 94:3905-12.

  21. Biondi B, Wartofsky L. Treatment With Thyroid Hormone. Endocrine Reviews, June 2014, 35(3):433512.

  22. Bolk N, Visser TJ, Kalsbeek A, van Domburg RT, Berghout A. Effects of evening vs morning thyroxine ingestion on serum thyroid hormone profiles in hypothyroid patients. Clin Endocrinol (Oxf) 2007; 66: 43-8.

  23. Rajput R, Chatterjee S, Rajput M. Can levothyroxine be taken as evening dose? Comparative evaluation of morning versusevening dose of levothyroxine in treatment of hypothyroidism. J Thyroid Res 2011; 2011: 505239.

  24. Raza SA, Ishtiaq O, Unnikrishnan AG, Khan AK, Ahmad J, Ganie MA, Azad K, Baruah M,Pathan MF. Thyroid diseases and Ramadan.Indian J Endocrinol Metab 2012; 16: 522-4.