A 37 year old female with a recent history of dizziness, shakiness and intolerance to heat and sees her GP. Her blood tests come back as normal apart from a thyroid stimulating hormone (TSH) of <0.05 mU/l and free thyroxine (T4) of 30.1 pmol/l.
Normal Ranges of TSH, T4, and T3
The results received from the patient blood tests indicate abnormal levels of these hormones. The reference ranges of these hormones are: TSH has a range of 0.4-4.5 mU/l, free T4 has a range of 9.0-25.0 pmol/l and free T3 has a range of 3.5-7.8 pmol/L http://www.btf-thyroid.org/information/quick-guides/97-thyroid-function-tests. These ranges do vary by small margins depending on the source; however from these ranges it clearly indicates that …show more content…
Hyperthyroidism is caused by over active thyroid, producing excess thyroid hormone; this causes a feedback loop which reduces the amount of TSH which leads to an extremely low or sometimes undetectable level of TSH in Patient samples. The diagnosis would be taken further to find the condition that caused the thyroid to become overactive, there a list of possibilities but the most common being graves’ disease, toxic adenoma and toxic multinodular goiter. http://site.ebrary.com/lib/aston/reader.action?docID=10674910&ppg=13. The patient is also female; this makes them ten times more likely than a man to develop hyperthyroidism and is prevalence within the population is 0.5-2% for women …show more content…
Once this occurs it causes the production of the thyroid hormones within the follicular cells which are then released from the thyroid too carry out the necessary functions. However within the patient the T4 levels are very high this causes a negative feedback to the pituitary gland, preventing release of TSH as no more T4 is needed so therefore no more stimulation of the thyroid gland is