There are several different types of thyroid diseases. The thyroid disease that is most commonly associated with fatigue is an under active thyroid known as hypothyroidism. However sometimes people with an over active thyroid can also experience symptoms of fatigue.
Thyroid lumps or nodules are very common but they almost always need formal assessment by an endocrinologist or thyroid surgeon. Therefore I am not going to focus on thyroid nodules here. If you have a thyroid lump please discuss referral to a specialist with your primary care doctor.
Thyroid dysfunction can develop quite gradually so tell-tail signs can easily be missed. The thyroid can become inflamed which is known as thyroiditis. This can cause severe symptoms along with thyroid discomfort and swelling. Thyroid blood tests can initially appear almost normal in this situation. Primary care doctors sometimes dismiss symptoms if thyroid blood tests are normal but this type of thyroid problem can be very debilitating and the test results can can fluctuate because of erratic thyroid hormone production. Early treatment in thyroiditis can resolve symptoms and restore health and well being.
If your doctor thinks you have a thyroid problem you will almost certainly arrange a thyroid blood test for you. If the test is borderline but you are feeling very unwell with symptoms related to your thyroid (for symptom lists see UpToDate on-line for patients), this might suggest that your thyroid function is fluctuating. Therefore follow-up with repeat thyroid blood tests in a few weeks is needed in this situation and if there is lack of clarity about what to do then a specialist opinion from a thyroid specialist should be sought.
If you have been diagnosed with a thyroid problem you can find very accurate information about your condition on UpToDate on-line for patients (link above).