Signs of hyperthyroidism are due to the presence of excess thyroid in blood. Due to this, the patient feels anxious and fidgety even in relaxed conditions. As thyroid is related to skin, the latter is directly affected by the disorder. The skin starts to feel warm, moist and velvety. Hair, on the other hand, becomes fine and silky, and discoloration of fingernails occur, leading to browning. Several nervous system-related signs start to occur, like rapid speech, faint tremors in fingers and tongue and unintentional stares and blinking. Apart from the above, one starts experiencing high blood pressure, arrhythmia and auscultation. Other symptoms related with hyperthyroidism are nervousness, palpitations, insomnia, weakness in muscles, frequent bowl movements, diarrhea, excessive sweating, abnormal weight loss, intolerance towards heat and amenorrhea. 

The second step is to check the functionality of thyroid gland. There are several lab tests that are conducted for this in which thyroid-stimulating hormone (TSH) is measured. As TSH is directly involved in the functioning of thyroid gland, such as regulation of hormone levels, the results related to this hormone helps the doctors in getting an outline of the situation of the thyroid gland, before any further tests are conducted. If the hormone is less than 0.3 mU/L, hyperthyroidism is more likely the reason for various symptoms in the body.

Blood test is the third step, and second most important step, to check for hyperthyroidism, as thyroid hormones are present in the blood through which they are transported to other parts of the body. In this, a blood sample of approximately 3 ml from adult, or 1 ml from child, is taken, avoiding any clotting. Various tests are performed on this sample to determine the amount of red blood cells, hemoglobin and other components present in it. If the result is similar to that of anemia, granulocytosis and lymphocytosis, the patient may be diagnosed with hyperthyroidism. 

This test is conducted to check the amount of other non-blood components, such as calcium and other fluids, in the body. For this, a sample of electrolyte is taken from the body, and tests are conducted. As presence of calcium in the body is directly related with the hormones secreted by thyroid, this metal is an indicator of any abnormality in the field of thyroid hormones. If the results are closer to those shown by hypercalcemia, such as an abnormal increase in the presence of calcium in the body, the patient may be diagnosed with hyperthyroidism. 

After dealing with signs, gland, blood, and electrolytes, liver is brought into picture. In the liver function tests, various markers are used to determine the extent to which the liver is functioning properly. If alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase are found to be higher than normal, the liver is not completely healthy, and the concerned person may be diagnosed with hyperthyroidism. 

Once it is confirmed that the patient is diagnosed with a thyroid-related disorder or disease, he/she is sent for thyroid uptake scan. Thyroid is scanned in order to confirm the lab results based on the thyroid gland. These scans are used to find out specific nodules that are responsible for diseases and disorders. It is by studying these nodules that the doctor finalizes the exact disease prevalent in the region. In this, the patient is asked to gulp a radioactive iodine capsule. This element is then used to scan the gland from inside. Gamma rays are used to capture the images of interior of thyroid gland, and these are compared with ideal gland images and studied extensively. If there are symptoms in the gland that point to hyperthyroidism, hypothyroidism or goitre, they are discovered in these images. 

Unlike thyroid uptake scan, thyroid ultrasound is a harmless, painless way of scanning the thyroid gland. In this, a transducer is run over the neck of the patient. The sound waves emitted from the wand-like instrument help in capturing the images of the thyroid gland. These images are then studied by the concerned doctors before the proper results are derived. As this test happens solely from outside, unlike thyroid uptake scan in which there is an ingested radioactive iodine to compliment the external module, the images recovered may not be as exacting as the previous scan, but in some cases, they are sufficient to separate solid nodules from cystic nodules, which is quite necessary for further tests. 

If a solid, cold nodule, a type of lump in the thyroid, is discovered, further tests are conducted on the nodule to find out its actual nature. Different nodules in thyroids represent different scenarios, ranging from harmless formations to cancerous developments. So, in order to find out the exact type of solid nodule, tests are conducted. In this, two tests are most important.

Fine needle biopsy is the act of removing a small amount of fluid from the nodule in the thyroid gland. This fluid contains the cells that are then studied under a microscope and results are derived. If these results match with the ones prominent in case of hyperthyroidism, the patient may be diagnosed with the disease. This test is painful, as a needle is inserted in the thyroid gland.

CT scans for head and neck are also taken to evaluate for metestatic disease. The results are used to confirm the occurrence of hyperthyroidism. 

Once diagnostics are done, evaluation of hyperthyroidism starts. In this, the tests are conducted to confirm the disease. The first step of evaluation is to check thyroid stimulating hormone (TSH). In this, some lab-based tests are performed, based on which TSH level in the gland is checked. If there is an increase in TSH, a test for free T4 is conducted. 

Thyroxine (T4) is a thyroid hormone. It is measured using radioimmunoassay. Free T4 is then measured from bound serum T4, given that the latter is not affected by Thyroid Binding Globulin (TBG). T4 is measured in two cases in relation with TSH measurements. If the TSH level is suppressed, free T4 tests are conducted to find whether the thyroid is affected by more lethal diseases, such as thyroid cancer, Grave’s disease or goitre. If the TSH level is higher than permissible, free T4 testing is done to find whether the case of hyperthyrodism is primary or secondary. If the presence of T4 is found to be high, that is above 1.9 ng/dl, chances of secondary hyperthyroidism are there. To verify this, an MRI scan of pituitary gland is taken, and the results are then compared with the notes. If it is low or normal, the patient is diagnosed with hypothyroidism, a case in which the thyroid gland secretes lower amount of thyroid hormones than usual. 

The final evaluation to check the disease is to check thyroglobulin present in the thyroid. Thyroglobulin is a protein that is produced by the thyroid gland for use within itself. Its function is to produce the thyroid hormones: thyroxine (T4) and triiodothyronine (T3). It is also the site in the body where iodine is stored. So, by evaluating thyroglobulin, the doctors can find the precise amount of iodine present in the body. If thyroglobulin is found to be lower than permissible limits, it is inferred that the thyroid hormones are coming from outside, as there is not enough thyroglobulin to produce such high amount of hormones. On the other hand, if thyroglobulin levels are found to be higher than usual, three cases can be inferred. First, the body is diagnosed with hyperthyroidism. Second, there is ectopic thyroid hormone production taking place in the body. This case is more prevalent in females. The third case is excess exposure of iodides that can explain the increased amounts of iodine in the gland.