A starting dose of 50 mcg of Thyronorm (levothyroxine) is a very standard and appropriate dose for a TSH level of 7.25, which indicates a mildly underactive thyroid. Regarding your cycle, thyroid hormones closely regulate menstruation. An underactive thyroid itself often causes irregular or missed periods. When starting levothyroxine, your body undergoes a temporary hormonal adjustment, which can sometimes delay your period. As your hormone levels stabilize over the next few weeks, your cycle should become regular. Please share these updates with your doctor to monitor your progress.