Ramadan Fasting and Changes in Thyroid Function in Hypothyroidism: Identifying Patients at Risk.

Area of Science:

• Endocrinology
• Metabolic Disorders

Background:

• Ramadan fasting (RF) alters meal timing, potentially affecting medication absorption and thyroid function (TF).
• Hypothyroidism patients on levothyroxine replacement therapy may be susceptible to these changes.

Purpose of the Study:

• To investigate the short- and long-term effects of Ramadan fasting on thyroid function in patients with primary hypothyroidism on levothyroxine.
• To identify factors associated with loss of thyroid control during Ramadan.

Main Methods:

• Retrospective analysis of TF tests in 481 patients before Ramadan (BR), and 1-2 weeks (PR1) and 3-6 months (PR2) post-Ramadan.
• Assessment of serum thyrotropin (TSH), free thyroxine (fT4), and free triiodothyronine (fT3) levels.
• Multivariable regression analysis to determine predictors of thyroid control loss.

Main Results:

• TSH levels significantly increased at PR1 compared to BR (p < 0.001), with a concurrent decrease in fT4 and fT3 (p < 0.001).
• 25.5% of patients with controlled TF at BR showed deterioration at PR1; 61% of those with uncontrolled TF remained so.
• Higher baseline TSH was significantly associated with loss of thyroid control during Ramadan (OR 1.5, p < 0.001).

Conclusions:

• Ramadan fasting can negatively impact thyroid function in levothyroxine-treated hypothyroid patients.
• The effects are generally modest and transient, but a significant minority, particularly those with higher baseline TSH, may experience clinically relevant changes.