Download The Endogenous and Exogenous Principals

TSH concentrations……………...… what value should be aimed for ?
The Endogenous and Exogenous Principals and effect.
“The difficulty in interpreting serum TSH concentrations is to decide what value should be aimed for in patients taking thyroxine
replacement. It is not sufficient to satisfy the recommendations of the American Thyroid Association or the AMA (Australia) by
simply restoring both serum T4 and TSH concentrations to normal (most people would be under treated), as in our experience most
patients feel well only with a dose resulting in high / normal free T4 and low / normal TSH concentration, and those patients with
continuing symptoms despite ‘adequate ( blood tests say you should be well ) doses of thyroxine’, may be slightly under-replaced.
Some patients (the majority) achieve a sense of wellbeing only if free T4 is slightly elevated and TSH low or undetectable (<<0.1).
The evidence that this exogenous [ imposed from outside, i.e.; taking T4 and or T3 combination therapy ] form of subclinical
hyperthyroidism (self induced) is harmful, is lacking in comparison to the endogenous [produced internally] variety associated with
nodular goitre, and it is not unreasonable to allow these patients to take a higher dose if T3 is unequivocally normal.”
Example 1:
That if blood tests shown in patient ‘A’ reflect Subclinical Hyperthyroid due to Thyroid disease (endogenous). Yet, another patient,
patient ‘B’ is feeling good on a progress level of Thyroxine replacement therapy (exogenous), displaying the same blood test results
while the second patient, patient ‘B’, is showing no signs or symptoms of subclinical hyperthyroidism, may well be within an optimal
point of treatment on a progress level of Thyroxine replacement for their Hypothyroidism.
TFT QML Pathology:
Thyroid Stimulating Hormone
free Thyroxine (fT4)
free T3
0.05 mU/L
22 pmol/L
5.9 pmol/L
(0.20-4.00)
(10-20)
(2.8-6.8)
TSH low or undetectable
T4 is slightly elevated
T3 is unequivocally normal
Progress level - on Thyroxine replacement. 200mcg
* Conventional / normal as opposed to OPTIMAL medical opinion would say that patient ‘B’, was becoming thyrotoxic / sub
acute Hyperthyroidism or excess treatment on T4, yet the patient, patient ‘B’, has no Hyperthyroid’ symptoms and a general feeling of
well being and hope. OPTIMAL medical opinion considers these results if congruent to other TFT results taken over time, to be
conducive to patient ‘B’s personal set point, resulting in an improved quality of health.
Pituitary Gland: Situated at the base of the brain (above the roof of the mouth), sends out instructions to many other glands
telling them how much hormone to produce. One such hormone is TSH (Thyroid Stimulating Hormone) which signals to the thyroid
gland to make thyroid hormone. The pituitary gland determines how much TSH to secrete (i.e., how much thyroid hormone to tell the
thyroid gland to make) based on:



How much thyroid hormone is available
How much thyroid hormone the body needs
How much thyroid hormone the body (actually the adrenals) can tolerate
TSH (Thyroid Stimulating Hormone): Is a hormone produced by the pituitary gland and whose function is to signal the thyroid gland
to make more thyroid hormone (T4). It represents the pituitary's need or desire for more thyroid hormone (T4 or T3). Thus a high
TSH level is like the pituitary saying it has a ‘high need for thyroid hormone’ or the body can tolerate more thyroid energy than it is
getting and it is meant to generate more thyroid hormone production. Conversely, a low TSH reflects either a low need or desire for
thyroid hormone or a low tolerance for the thyroid hormone and is meant to reduce thyroid hormone production. An optimal value of
TSH means the thyroid hormone levels match the body’s energy needs and/or ability to utilize the energy.
Example 2:
Patient B’s TSH of ‘0.05 mU/L’ (0.20 - 4.00) is the pituitary's answer to the level of Thyroxine replacement induced Exogenously.
(imposed from outside - the taking of Thyroxine replacement -T4) . In all probability there is a strong case for having a different
range for TSH in patients on thyroxine replacement.
The hypothesis is that a doctor cannot know whether a concentration of free T4 or TSH within wide reference ranges is normal for
that individual. Each individual’s thyroid function is unique and that a test result within laboratory reference ranges is not necessarily
normal for that individual. Where as slight fluctuations in Thyroid Function Test (TFT) results should be taken into consideration
before a titrate (adjusting) of the dose of thyroxine.
As far as Thyroid function is concerned the operative word is “unique” and each patient must be treated as an individual not as part
of a designated populous.
(In cases of chronic adrenal fatigue, the body (actually the adrenals) can only handle a low amount of metabolic energy, so the TSH
will usually be low <0.01. This is an example of the body 'down-regulating' the thyroid energy.)
The successful management and treatment of Thyroid disease requires a sympathetic relationship between doctor, patient
and particularly spouses. Doctors and friends who display the characteristics of empathy, acceptance of their patient and friend’s
suffering, being non judgemental and attentive with a commitment to continued care and support are more likely to maximise the
effects of treatment and the general well being of all.
What is clearly needed now is a new prospective and adequate answers to the lingering but critical questions regarding the effects of
Thyroid treatment and Thyroid failure on important end points, such as intellectual function, ischemic heart disease, and quality of
life, not to mention the “Social Impact of Thyroid Conditions”.
"Let's do.....All we can to do All we can.
Drs Anthony D Toft & Geoffrey J Beckett, “Thyroid function tests and hypothyroidism”
British Medical Journal, 8 February 2003; 326: 296-7
http://bmj.com/cgi/content/full/326/7384/295?ijkey=CFlqXBks53nhU
Rick Maynard Queensland Coordinator for Thyroid Australia
Thyroid Australia (Brisbane) and Brisbane Bulletin Board http://www.yourthyroidandyou.org
* Conventional / normal..... Not thinking outside the box.
DISCLAIMER - All materials supplied by Thyroid Australia (Brisbane) are for information
purposes only and do not constitute medical advice. For medical advice please see a Doctor.