You’ll need to have your TSH checked 6 to 10 weeks after a thyroxine dose change. You may need tests more often if you’re pregnant or you’re taking a medicine that interferes with your body’s ability to use thyroxine. The goal of treatment is to get and keep your TSH in the normal range. Babies with hypothyroidism must get all their daily treatments and have their TSH levels checked as they grow, to prevent mental retardation and stunted growth. Once you’ve settled into a thyroxine dose, you can return for TSH tests about once a year.