Thanks for the query. As per the history, you have been taking Tablet Thyronorm (50 mcg) for 2 years. I would like to know your age and whether you have got your Thyroid profile done in this span. Increased heart rate, tremor and palpitation may be an effect of hyperthyroid state alongwith heat intolerance. On the other hand cold intolerance may be an effect of Hypothyroidism. I would also like to enquire about your menstrual history (irregularities are often noted with thyroid dysfunction) and whether there has been any significant change in you weight over the past few months (weight loss is associated with hyperthyroidism and weight gain with hypothyroidism). Your symptoms are more in favour of a hyperthyroid state. At this stage, I would advise you to go for a complete Thyroid profile check up. If there is any abnormality, you would need to consult your physician for dose adjustment of Thyronorm. Hope this helps you.