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Posted by Tree Frog
on May 27, 2000 at 09:03:56:
May 21, 2000
Thyroid Testing Update
A just published review, by a Scottish biochemist, of the current standard practice of thyroid function testing brings to light many problems associated with conventional medicine's approach.
For example, there is no data on the relative importance of biochemical thyroid function tests and clinical symptoms and signs in assessing thyroid dysfunction. According to the author "We do not know how important the thyroid function tests are for making a diagnosis of thyroid dysfunction". In addition, he states the fact that the clinical aspects of assessing thyroid dysfunction are being sidelined is a cause for concern." In other words, doctors are ignoring their patient's symptoms as long as their blood work comes back in the "normal" range. However, the blood hormone levels may not always yield a correct diagnosis, with both false positive and false negative results.
Secretion of thyroid stimulating hormone (TSH) is influenced by many factors other than the negative feedback inhibition by thyroxine (T4) or triiodothyronine (T3). Levels of TSH are very often the sole parameter by which doctors diagnose hypothyroidism. According to the report, "symptoms are not considered a criterion by some authorities…the clinical features of hypothyroidism seem to have been relegated to the status of historical curiosities."
Another confounding factor is that changes in TSH, T4, and T3 concentrations during systemic illness are poorly understood and therefore thyroid function tests cannot be interpreted in these patients. Since rates of systemic illness are so high, especially in those with hypothyroidism, a high percentage of patients undergoing thyroid testing would fall into this category.
BMJ 2000; 320: 1332-1334 Original Article