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“We submit these ideas hoping that others will join us in re-evaluating thyroid treatment when maladaptive hypothyroidism occurs during weight loss attempts. Clinicians must use clinical skills and patient-centered concerns in the optimum evaluation and treatment of their patients and not succumb to blindly following an arbitrary system of defined normal lab values in making therapeutic decisions that greatly affect the well-being of their patients.” |
Lowered Pituitary Set Point.
The authors’ papers, I believe, also show a noteworthy drive to be
didactically helpful. In that vein, they have cast light on a
realistic and fortunate feature of the thyroid system: that when a
patient is in a low caloric state, it adapts with sophisticated and
complexity to the chronically low intake of calories by slowing
metabolism. But, as the authors write, “The patient is often told to
get more exercise and that s/he must be eating more calories than
realized.” And they show that reducing the patient’s thyroid hormone
dose is likely to slow metabolism even further. This misguided
treatment approach hinders the adaptive mechanism, reducing calorie
expenditure, and perpetuating the patients’ retention of excess
weight.
Rowsemitt and Najarian write that upon finding a lower in-range TSH,
“The provider is likely to conclude that there is nothing wrong with
the patient’s thyroid function despite the symptoms.” As they
explain, though, the provider is correct in one respect—there is
nothing wrong with the patient’s thyroid function. The patient’s
lowered TSH is caused by the pituitary’s lowered set point. That
lower set point is a life-preserving evolutionary adaptation to low
calorie intake.
Early humans and even earlier hominids underwent feast/famine cycles
that were beyond their control. Modern humans in developed countries
have largely eliminated famines. But in times when feast/famine
cycles were fairly common, those whose metabolism slowed down during
famines had an evolutionary advantage—that is, it enabled them to
survive. The survivors, through generations, spawned offspring
progressively better able to survive protracted times when food was
scarce.
They note that humans still have this adaptive advantage despite no
shortage of calories for most people today. The adaptation that
benefited our ancient ancestors now leads to many hypothyroid
patients continuing to suffer from hypothyroid symptoms and excess
weight. The reason is that clinicians in general lack an
understanding of the adaptive mechanism of a lowered pituitary set
point. The resulting lower TSH prompts them to reduce or stop
patients' thyroid hormone doses, worsening their symptoms and weight
gain.
Our main problem for many hypothyroid patients today is the
abundance of calories that would nullify our need for the adaptive
mechanism—had we enough time for evolutionary deletion of the set
point phenomenon.
I have touched on some of Rowsemitt and Najarian’s points from my
enthusiasm for their brilliant and insightful exposition. I am
convinced that their papers will do much needed good for hypothyroid
patients, especially the weight-laden ones. I strongly encourage
patients and clinicians alike to read, print, and disseminate Dr. Rowsemitt and
Dr. Najarian’s extraordinary papers.
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Rowsemitt, C.N. and Najarian, T.: TSH is not the answer: Rationale for a new paradigm to evaluate and treat hypothyroidism, particularly associated with weight loss. Thyroid Science, 6(4):H1-16, 2011.
Najarian, T. and Rosemitt, C.N.: Hypothyroidism, particularly associated with weight loss: Evaluation and treatment based on symptoms and thyroid hormone levels. Thyroid Science, 6(6)CR1-7, 2011.
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