Article on the faulty TSH indicator

[Guest guest]

http://nahypothyroidism.org/diagnosistreatment/

Diagnosis of hypothyroidism:

Are we getting what we want from TSH testing?

Hypothyroidism is a common disorder where there is inadequate cellular thyroid

effect to meet the needs of the tissues. Typical symptoms of hypothyroidism

include fatigue, weight gain, depression, cold extremities, muscle aches,

headaches, decreased libido, weakness, cold intolerance, water retention,

premenstrual syndrome (PMS) and dry skin. Low thyroid causes or contributes to

the symptoms of many conditions but the deficiency is often missed by standard

thyroid testing. This is frequently the case with depression,

hypercholesterolemia (high cholesterol), menstrual irregularities, infertility,

PMS, chronic fatigue syndrome (CFS), fibromyalgia, fibrocystic breasts,

polycystic ovary syndrome (PCOS), hyperhomocysteinuria (high homocystine),

atherosclerosis, hypertension, obesity, diabetes and insulin resistance.

The TSH is thought to be the most sensitive marker of peripheral tissue levels

of thyroid, and it is erroneously assumed by most endocrinologists and other

physicians that, except for unique situations, a normal TSH is a clear

indication that the person's tissue thyroid levels are adequate (symptoms are

not due to low thyroid) (see why doesn't my doctor know this). A more thorough

understanding of the physiology of hypothalamic-pituitary-thyroid axis and

tissue regulation of thyroid hormones demonstrates that the widely held belief

that the TSH is an accurate marker of the body's overall thyroid status is

clearly erroneous.

The TSH is inversely correlated with pituitary T3 levels but with physiologic

stress (1-32), depression (33-38), insulin resistance and diabetes

(28,39,116,117), aging (30,40-49), calorie deprivation (dieting)(27, 50-57),

inflammation (5-8,22,108,109-111), PMS (58,59), chronic fatigue syndrome and

fibromyalgia (60,61), obesity (112,113,114) and numerous other conditions

(1-32), increasing pituitary T3 levels are often associated with diminished

cellular and tissue T3 levels and increased reverse T3 levels in the rest of the

body (1-62) (see pituitary diagram). The pituitary is both anatomically and

physiologically unique, reacting differently to inflammation and physiologic

stress than every other tissue in the body (1-20,50-52,62,63)(see deiodinase).

The conditions above stimulate local mechanisms to increase pituitary T3 levels

(reducing TSH levels) while reducing T3 levels in the rest of the body (1-63).

Thus, with physiologic or emotional stress, depression or inflammation, the

pituitary T3 levels do not correlate with T3 levels in the rest of the body, and

thus, the TSH is not a reliable or sensitive marker of an individual's true

thyroid status (see deiodinase).

Serum levels of thyroid hormones

(see serum thyroid hormones graph on link)

Due to the differences in the pituitary's response to physiological stress,

depression, dieting, aging and inflammation as discussed, most individuals with

diminished tissue levels of thyroid will have a normal TSH (1-63). Doctors are

taught that if active thyroid (T3) levels drop, the TSH will increase. Thus,

endocrinologists and other doctors tell patients that an elevated TSH is the

most useful marker for diminished T3 levels and that a normal TSH indicates that

their thyroid status is " fine " . The TSH is, however, merely a marker of

pituitary levels of T3 and not of T3 levels in any other part of the body. Only

under ideal conditions of total health do pituitary T3 levels correlate with T3

levels in the rest of the body, making the TSH a poor indicator of the body's

overall thyroid status. The relationship between TSH and tissue T3 is lost in

the presence of physiologic or emotional stress (1-32), depression (33-38),

insulin resistance and diabetes (28,39), aging (30,40-49)(see thyroid hormones

and aging graph), calorie deprivation (dieting)(50-57), inflammation (5-8,22),

PMS (58,59), chronic fatigue syndrome and fibromyalgia (60,61), obesity

(112,113,114) and numerous other conditions (1-63). In the presence of such

conditions, the TSH is a poor marker of active thyroid levels and thyroid status

of an individual, and a normal TSH cannot be used as a reliable indictor that a

person is euthyroid (normal thyroid) in the overwhelming majority of patients.

Value of Serum T4

The suppression of TSH with physiologic and emotional stress and illness

suppresses the production of T4 (1,2,9,64-68), which would tend to lower serum

T4 levels. In the presence of such conditions, there are, however, competing

effects that result in an increase in serum T4 while further reducing tissue

levels of T3 levels, making serum T4 (or free T4) a poor marker of tissue

thyroid level, as is the case with the TSH. Such effects include a suppression

of tissue T4 to T3 conversion (misleadingly increasing serum T4 levels)

(1-68,76) with an increased conversion of T4 to reverse T3

(12,14,18,35,36,41,59,69-74,85) and an induced thyroid resistance with reduced

uptake of T4 into the cells (misleadingly increasing serum T4 levels)

(16,1976-84) in all tissues except for the pituitary (84). Although all such

effects reduced intracellular T3 in all tissues except for the pituitary, the

serum T4 level can be increased, decreased or unchanged. Consequently, serum T4

levels oftentimes do not correlate with tissue T3 levels and, as with the TSH,

the serum T4 level is often misleading and an unreliable marker of the body's

overall thyroid status (see serum thyroid levels in stress and illness).

Current best method to diagnosis

With increasing knowledge of the complexities of thyroid function at the

cellular level, it is becoming increasingly clear that TSH and T4 levels are not

the reliable markers of tissue thyroid levels as once thought, especially with

chronic physiologic or emotional stress, illness, inflammation, depression and

aging. It is common for an individual to complain of symptoms consistent with

hypothyroidism but have normal TSH and T4 levels. While there are limitations to

all testing and there is no perfect test, obtaining free triiodothyronine,

reverse triiodothyronine, and triiodothyronine/reverse-triiodothyronine ratios

can be helpful to obtain a more accurate evaluation of tissue thyroid status and

may be useful to predict those who may respond favorably to thyroid

supplementation (1,11,12,14,18,35,36,41,59,69-74,85) (see serum thyroid levels

in stress and illness). Many symptomatic patients with low tissue levels of

active thyroid hormone but normal TSH and T4 levels significantly benefit from

thyroid replacement, often with significant improvement in fatigue, depression,

diabetes, weight gain, PMS, fibromyalgia and numerous other chronic conditions

(86-99).

With an understanding of thyroid physiology, it becomes clear why a large

percentage of patients treated with T4 only preparations continue to be

symptomatic. Thyroxine (T4) only preparations should not be considered the

treatment of choice and are often not effective in conditions associated with

reduced T4 to T3 conversion, reduced uptake of T4 or increased T4 to reverse T3

conversion. As discussed above, with any physiologic stress (emotional or

physical), inflammation, depression, inflammation, aging or dieting, T4 to T3

conversion is reduced and T4 will be preferentially converted to reverse T3

(12,14,18,35,36,41,53,69-74,85), which acts a competitive inhibitor of T3

(blocks T3 at the receptor) (100-104), reduces metabolism (100,103,104),

suppresses T4 to T3 conversion (101,103) and blocks T4 and T3 uptake into the

cell (105).

While a normal TSH cannot be used as a reliable indicator of global tissue

thyroid effect, even a minimally elevated TSH (above 2) demonstrates that there

is diminished intra-pituitary T3 level and is a clear indication (except in

unique situations such as a TSH secreting tumor) that the rest of the body is

suffering from inadequate thyroid activity because the pituitary T3 level is

always significantly higher than the rest of the body and the most rigorously

screened individuals for absence of thyroid disease have a TSH below 2 to 2.5

(106). Thus, treatment should likely be initiated in any symptomatic person with

a TSH greater than 2. Additionally, many individuals will secrete a less

bioactive TSH so for the same TSH level, a large percentage of individuals will

have reduced stimulation of thyroid activity, further limiting the accuracy of

TSH as a measure of overall thyroid status. Reduced bioactivity of TSH is not

detected by current TSH assays used in clinical practice.

Due to the lack of correlation of TSH and tissue thyroid levels, as discussed, a

normal TSH should not be used as the sole reason to withhold treatment in a

symptomatic patient. A symptomatic patient with an above average reverse T3

level and a below average free T3 (a general guideline being a free T3/reverse

T3 ratio less than 2) should also be considered a candidate for thyroid

supplementation (13,14,18,69-76,85-106). A relatively low sex hormone binding

globulin (SHBG) and slow reflex time can also be useful markers for low tissue

thyroid and levels and can aid in the diagnosis of tissue hypothyroidism

(93,107,115).

A study published in the Journal of Clinical Endocrinology and Metabolism

assessed the level of hypothyroidism in 332 female patients based on a clinical

score of 14 common signs and symptoms of hypothyroidism and assessments of

peripheral thyroid action (tissue thyroid effect). The study found that the

clinical score and ankle reflex time correlated well with tissue thyroid effect

but the TSH had no correlation with the tissue effect of thyroid hormones (118).

The ankle reflex itself had a specificity of 93% (93% of those with slow

relaxation phase of the reflexes had tissue hypothyroidism) and a sensitivity of

77% (77% of those with tissue hypothyroidism had a slow relaxation phase of the

reflexes) making both the measurement of the reflex speed and clinical

assessment a more accurate measurement of tissue thyroid effect than the TSH.

A combination of the serum levels of TSH, free T3, free T4, reverse T3, anti-TPO

antibody, antithyroglobulin antibody and SHBG should be used in combination of

with clinical assessment and measurement of reflex speed and basal metabolic

rate to most accurately determine the overall thyroid status in a patient.

Forgoing treatment based on a normal TSH without further assessment will result

in the misdiagnosis of mismanagement of a large number of hypothyroid patients

that may greatly benefit with treatment. Simply relying a TSH to determine the

thyroid status of a patient demonstrates a lack of understanding of thyroid

physiology and is not evidence based medicine (see Why my Endocrinologist

Doesn't Know All of This). In patients with elevated or high normal reverse T3

levels, T4 only preparations should not be considered adequate and T3 containing

preparations, in particular timed released T3, should be considered the

treatment of choice.

[Guest guest]

Hi, What a lovely article- now why don't all our docs think like this. > thyroid treatment > From: marsaday1971@...> Date: Thu, 8 Jul 2010 08:19:18 +0000> Subject: Article on the faulty TSH indicator> > > http://nahypothyroidism.org/diagnosistreatment/> > Diagnosis of hypothyroidism:> > Are we getting what we want from TSH testing?> > Hypothyroidism is a common disorder where there is inadequate cellular thyroid effect to meet the needs of the tissues. > > > ------------------------------------> > TPA is not medically qualified. Consult with a qualified medical practitioner before changing medication.> >