The TRH Stimulation Test: Is There a Place for This Challenge Test?

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The TRH Stimulation Test:

Is There a Place for This Challenge Test?

http://thyroid.about.com/od/gettestedanddiagnosed/a/trhtest.htm?nl=1

From Mary Shomon,

 

Manhattan-based alternative practitioner Dr. Rafael Kellman is trying to

revive interest in the TRH Stimulation Test, a test considered totally outmoded

by

most practitioners.

 

Understanding the TRH Test

 

To understand how the TRH Stimulation Test works, it's first helpful to

quickly review how the various brain hormones interact with the thyroid.

 

* Your hypothalamus is a gland in your brain that secretes thyrotropin

releasing hormone (TRH).

* When TRH is released, it stimulates your pituitary gland -- also in the

brain -- to release thyroid stimulating hormone (TSH).

* TSH stimulates the thyroid itself to make thyroid hormones.

 

Most practitioners consider the best test of thyroid function to be the TSH

test, which measures the circulating level of TSH in the bloodstream at one

point in time. The TSH test results are then interpreted; levels higher or lower

than a so-called normal range are considered evidence of potential thyroid

disease.

 

The TRH test is different. A baseline TSH test is done. Then you are given an

injection of TRH, which stimulates the pituitary to release TSH. A second

blood sample is drawn 20 to 30 minutes later, and the TSH level is retested. TRH

is known generically as protirelin (pronounced proe-TYE-re-lin). Its brand

name used to be Thyrel, but production of Thyrel was discontinued several years

ago.

 

Kellman believes that this test is the " best way to detect subtle thyroid

problems... " and that it overcomes limitations of the TSH test. According to

Kellman:

 

The TSH test is a picture in time of circulating levels of thyroid hormone.

But by challenging the thyroid, the TRH Stimulation Test evaluates the

thyroid's actual ability to function in real life.

 

How Does the TRH Test Differ from the TSH Test?

 

One way to look at it is to consider the difference between the TRH

Stimulation Test and the TSH test, much like a cardiac stress test is compared

to a

cardiogram, or a glucose tolerance test is compared to fasting glucose level. In

a stimulation test, the challenge may reveal an impairment in the thyroid.

 

With most practitioners, use of the TRH Stimulation Test was replaced by the

TSH test. Conventional doctors consider the TSH test highly accurate, and it

requires only one blood draw and no special supplies. In comparison, the TRH

test requires two separate draws a half hour apart, availability of TRH, and

knowledge of how to accurately perform and interpret the test.

 

The TRH test is occasionally used to help identify secondary hypothyroidism

(hypothyroidism due to pituitary problems) and tertiary hypothyroidism

(hypothyroidism due to hypothalamic disorder). But there are only a few doctors

in the

U.S. who know how to use the TRH Stimulation Test. These doctors believe the

test is important when traditional TSH tests results are borderline, and when

a patient has obvious thyroid symptoms but normal TSH results.

 

Says Kellman:

 

In some individuals (and depending on the physician's interpretation of the

laboratory tests), outright hypothyroidism may take as long as 20 years to

develop. With the help of measures such as the TRH stimulation test, I am able

to

diagnose hypothyroidism when the onset of symptoms (fatigue, weight gain,

etc.) precedes abnormal laboratory values. Early intervention thus may save

patients from years of needless suffering.

 

What Should You Do?

 

At present, it is almost impossible to get a TRH test. The drug needed for

the test, protirelin, is no longer manufactured. The only protirelin that is

apparently available is via compounding pharmacies. Whether or not that

protirelin is of sufficient quality to conduct the test is a question that some

practitioners have raised. If you find a practitioner who does do the TRH test,

however, keep in mind that the TRH Stimulation Test and protirelin TRH should be

used with caution in anyone with:

 

* Asthma

* Chronic obstructive pulmonary disease

* Heart disease caused by inadequate blood flow to the heart

* Reduced activity of the pituitary gland (hypopituitarism)

* Pregnancy

 

Sources:

Mary Shomon Interview with Rafael Kellman, 2005

RxList.com: Thyrel/Protirelin Profile

 

Mary Shomon, About.com's Thyroid Guide since 1997, is a nationally-known

patient advocate and best-selling author of 10 books on health, including " The

Thyroid Diet: Manage Your Metabolism for Lasting Weight Loss, " " Living Well With

Hypothyroidism: What Your Doctor Doesn't Tell You...That You Need to Know, "

" Living Well With Graves' Disease and Hyperthyroidism, " " Living Well With

Autoimmune Disease, " " Living Well With Chronic Fatigue Syndrome and

Fibromyalgia, "

and the " Thyroid Guide to Fertility, Pregnancy and Breastfeeding Success. "

Click here for more information on Mary Shomon

http://thyroid.about.com/mbiopage.htm

 

Updated: July 24, 2007