Comparison Between Variable Time Regimen of Dosing L-Thyroxine for Treatment Hypothyroid Fasting Ramadan

Inclusion Criteria: \- All included patients will be euthyroid, and stable on the same L T4 dose for at least 3 months before the start of Ramadan. Exclusion Criteria: * Exclusion criteria will be thyroid cancer patients requiring suppressive therapy, central hypothyroidism, pregnancy, coronary heart disease, arrythmia, chronic heart failure, liver cirrhosis, renal failure, acute medical, or surgical illness at the time of evaluation to avoid acute and chronic non thyroidal illness syndromes.