Q: What is the difference between viral thyroiditis and Hashimoto's thyroiditis? Initial TSH was 0.01, which rose to 17, six weeks later. Free T4 is stable at 0.58. Should treatment by thyroid replacement medication be given for hypothyroidism in either case? What is the dangerous level for TSH or free T4?

A:Hashimoto's thyroiditis is an autoimmune thyroid disease. This means that in blood there are antibodies, which destroy the thyroid gland. Most of these patients have hypothyroidism and that needs life-long treatment. These conditions can be differentiated by doing Anti-TPO test, which will be positive in Hashimoto’s thyroiditis. Viral thyroiditis is a nonspecific thyroid inflammation related to viral agents (not very well defined) and may be reversible. Usually thyroid replacement is needed when TSH is above 10. But before starting treatment, one needs to take into account other tests like Lipid profile, Creatinine level, Haemoglobin and ECG.