How Was Your Thyroid Checked? Why TSH Alone Is Not Enough

Again and again I see patients that come to me presenting with symptoms that may be related to thyroid disorders, but upon questioning I find out that they have not been fully assessed by their medical doctor. Often a TSH (thyroid stimulating hormone) test is done and they are told that because their TSH value is “normal” their thyroid must be normal. Many people with thyroid conditions go untreated for this reason.  A TSH value alone is not enough, especially if you are experiencing symptoms that indicate hypothyroidism.

TSH values do not accurately reflect the functional state of the thyroid. Most North American labs indicate a normal TSH reference range to be between 0.5 and 5.5. But, in 2001, the American Association of Clinical Endocrinologists made the following statement, “Even though a TSH level between 3.0 and 5.0 is in the normal range, it should be considered suspect since it may signal a case of evolving thyroid under activity.” Basically, this means that they believe values above 3 need to be investigated.

The February 2002 issue of the Journal of Clinical Endocrinology and Metabolism noted that amongst a disease-free population (those who do not have any indication of thyroid antibodies) the mean TSH level is 1.5. Taking into account all the preceding information, I recommend that any TSH value above 2 in combination with symptoms suggestive of hypothyroidism should be investigated further with a comprehensive thyroid panel.

To clarify even further whether a thyroid panel needs to be ordered, I recommend incorporating two other diagnostic systems. Together, these components make up a 3 Part Screening Method for Thyroid Disease:

1. Order TSH as part of an initial metabolic lab panel and use the optimal range as noted below

2. A thorough case history, including specific questions to assess the functional status of the thyroid

3. Basal body temperature analysis – your body temperature reflects your metabolism, which is largely determined by the hormones secreted by the thyroid; therefore looking at the average basal body temperature over the course of a few days can provide additional information about the health of the thyroid gland

Combining all three screening tools will provide enough information to make it very clear whether or not a complete thyroid panel needs to be ordered.

A complete thyroid panel would include the following tests (optimal reference ranges are included):

TSH: 1.2 – 2.0 µIU/mL

free T3: 2.3 – 4.2 pg/ml

free T4: 0.7 – 2.4 ng/dl

total T4: 6.0 – 12.0 mcg/dl

reverse T3: 14.9 – 26.1 ng/dl

TPO (anti thyroglobulin antibody)

These additional tests provide information on hypo and hyper thyroidism, altered peripheral conversion of T4 into T3, and whether the individual is suffering from an auto-immune condition that affects the thyroid. By knowing exactly what area or reaction along the pathway is out of balance we can better individualize and focus treatment.

Take home message: if you are experiencing symptoms that may be related to a thyroid disorder (covered in a previous post) do not settle for being diagnosed by TSH alone, especially if your TSH value falls outside of the optimal range

Do you suffer from hypothyroidism? What has been your biggest challenge? Share your story and post a comment.