Guest Author - Jim Lowrance
This article is similar in point to my article entitled “Is TSH Always Accurate?” but in this one, I will address other aspects of problems presented by TSH-only testing in some patients.
Many new hypothyroid patients, who are started on thyroid hormone therapy, will have their treatment monitored by TSH testing only. TSH (Thyroid Stimulating Hormone) is not a thyroid hormone but a pituitary gland hormone that reflects the T-4 and T-3 thyroid hormone levels. In most cases it does so accurately but in less common cases, TSH only testing can miss cases of inadequate treatment and cases of over-treatment as well. This happens in patients whose TSH levels do not accurately reflect their thyroid hormone levels. While this is not common, it occurs often enough to demonstrate the need by treating doctors, to order tests of T-4 and T-3, along with TSH, for at least the first two or three blood retests to monitor thyroid hormone therapy.
While I'm not a doctor but rather a well-studied Thyroid Patient Advocate, I have corresponded with 100s of patients over the past five years and I have formed some strong opinions in regard to hypothyroid treatment and the blood retest monitoring of it.
I feel that newly treated hypothyroid patients need to be tested for TSH, Free T-4 and Free T-3, for at least the first couple of blood test repeats/follow-ups to monitor their thyroid hormone replacement therapy. I say this because there are some patients whose TSH levels are not accurate in reflecting their thyroid hormone levels. Some patients must have their TSH suppressed very low before their thyroid hormone levels from the replacement therapy place their T-4 and T-3 at adequate levels for them (above mid-range and higher-normal). I'm an example of TSH that needs suppressed more than the average patient. My latest TSH blood retest result was at 0.001 which for the average patient, would be at seriously hyperthyroid level (over-treatment) but this only puts my Free T-4 at mid-range and my Free T-3 at between mid-range and high-normal, where I need to be to see symptom relief. My doctor knows for a fact that my TSH level does not accurately reflect my thyroid hormone levels.
On the other hand, some patients need a TSH that seems a little high for a treatment level but they experience toxicity (thyroid med induced hyperthyroidism) if their TSH goes below a 2.0.
It's difficult to know which patients may be in these uncommon situations, unless the Free T-4 and Free T-3 are tested along with TSH.
By testing the TSH and thyroid hormones together for the first couple of follow ups after beginning thyroid hormone therapy, it can also detect another uncommon condition called "impaired conversion". This one means that a patient is not converting enough T-3 in the body, from a T-4 only hormone replacement medication. In these cases, TSH may be well suppressed from an adequate T-4 level but the even more active T-3 hormone is staying low. These are the types of patients who need a combination T-4 and T-3 medication or need a T-3 added to the T-4 they are already taking.
The possibility of these type problems are why I feel more thorough lab evaluation is needed to monitor new patients on thyroid hormone therapy. Once it is established that their TSH accurately reflects their T-4 and T-3 levels, their thyroid hormone therapy can afterward be monitored with TSH-only testing.
If the more thorough testing is done and levels are shown to all be adequate or even best-optimized and a patient still experience symptoms, other blood tests may need to be done, to rule out other causes. Tests for anemia (CBC) or pre-anemia states such as lowering iron and/or ferritin levels and tests of B-12 level, glucose (HB A1C), inflammation, other autoimmunity, adrenal hormones, sex hormones etc..., may all need to be done in patients with significant unresolved symptoms.
