Many patients believe that their thyroid is “fine”, as when it was tested the results were “normal”. However, what most clients don’t understand is that the routine test for thyroid function doesn’t actually involve testing your thyroid hormones at all, but instead gauges your thyroid function by testing a pituitary hormone called TSH (or Thyroid Stimulating Hormone).
TSH (or Thyroid Stimulating Hormone) is the hormone released by your pituitary gland to stimulate thyroid gland hormone production. When stimulated by TSH, the thyroid gland produces T4 (inactive thyroid hormone) which is then converted to T3 (active thyroid hormone) in the liver. T3 is involved in stimulating a vast array of processes throughout the body, including the processes regulating your metabolism, energy and mental function.
If your TSH levels are outside the reference range, then further investigations are conducted. However, if your results fall into the upper or lower end of the reference range, this can mean that your thyroid function is sub-optimal and therefore not so “normal”.
As a general overview, abnormal TSH levels indicate the following:
- High TSH levels – may indicate an underactive thyroid. Your thyroid needs more TSH stimulation by the pituitary gland to do its job, with high TSH levels generally seen in Hypothyroidism or Hashimoto’s Thyroiditis.
- Low TSH levels – may indicate an overactive thyroid. Your thyroid requires less TSH stimulation by your pituitary gland, with low TSH levels usually seen (although not always) in Hyperthyroidism or Grave’s Disease.
These examples are generalisations, as sometimes TSH can be high when thyroid function is overactive and visa versa. That is why comprehensive testing is essential, if you have symptoms of possible thyroid imbalance.