Updated 2018-07-20
Hypothyroid signs, biomarkers and symptoms should play a greater role in diagnosis and therapy.
As discussed in the reference range section, normal-range levels of hormone in blood are not precise enough an indicator of true euthyroidism due to wide variability among individuals within the statistical range: “the TSH concentration needed to achieve similar concentrations of circulating thyroid hormones differs between individuals.” [52 (p. 1557)]
Because individuals differ genetically and in many other ways, they each need individually-adjusted thyroid hormone levels in blood.
In addition, blood levels are only the tip of the iceberg. As Chaker et al explain in 2017, “Although a normal TSH concentration reflects euthyroidism at the level of the pituitary, this might not necessarily reflect euthyroidism in all tissues.” [100] TSH is an insufficient marker because it is an isolated measure of the satisfaction of the pituitary gland alone – the pituitary gland does not adequately respond to low thyroid hormone levels in peripheral tissues and organs.
Some peripheral stimulation measures indicate the level of thyroid hormone action in bodily tissues, which may differ from what is expected given the level of TSH, T3 and T4 hormone in serum. [101, 102]
Low-cost, measurable clinical signs of hypothyroidism are relevant in screening, diagnosis and therapy. Among the most significant measurable signs are heart rate, body temperature, and the Achilles heel reflex, all of which can be tracked by the patient as well as measured by staff in the doctor’s office. [57, 103, 104, 105, 106, 107]
Laboratory test measures associated with hypothyroidism include cholesterol, cardiometabolic and inflammatory markers, insulin resistance markers, anemia markers, Vitamin E, and even the values found within a complete blood count. [108, 109, 110, 111, 112, 113, 114, 115]
Constitutional symptoms of hypothyroidism are often discredited by the term “nonspecific” because they may also point to problems other than (or secondary to) thyroid hormone deficiency. However, their nonspecific nature and subjectivity does not make them irrelevant in the clinical evaluation of a patient known to have thyroid disease. A 2017 review provides a comprehensive list of “signs” and connects them with “presentation” (symptoms) of peripheral hypothyroidism, such as neurological, psychological, and gastrointestinal impairments, changes in the blood, skin, hair, and kidney function.[100] Therefore, symptoms provide significant data in the context of test results and more directly measurable signs.
Scoring systems such as the “Billewicz diagnostic index,” “Zulewski’s clinical score” already exist and could be updated in the light of more recent research. [116] In this electronic age, each symptom can be quantified and scored through an patient questionnaire, with an option to complete it online before the visit. After the response has been submitted, results could be analyzed and graphed by a computer application before being reviewed by the doctor during the patient’s visit. This data would have the additional benefit of assisting future research on hypothyroidism if a patient research consent form was included in the survey.
This could save a little money on testing. When hypothyroid signs exist, we should order blood tests and those data ought to be considered during the interpretation of blood test results. When the patient is healthy and does not have significant signs of hypo- or hyperthyroidism, we can save our health care dollars and delay testing; we could just measure Free T3 occasionally to check on “true” euthyroid status.
Next page: Rationale: Free T3 testing
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