Thyroid Insufficiency. Is TSH Measurement the Only Diagnostic Tool?

W. V. BAISIER MD, J. HERTOGHE MD, & W. EECKHAUT MD : Journal of Nutritional & Environmental Medicine (2000) 10, 105113 : http://li123-4.members.linode.com/files/Thyroid%20Insufficiency.%20Is%20TSH%20Measurement%20the%20Only%20Diagnostic%20Tool_0.pdf Study to evaluate and compare laboratory indices of thyroid function. In this study symptoms of hypothyroidism correlate best with 24h urine free T3.

DISCUSSION
In 1963, Means et al. published an extensive list of the symptoms of hypothyroidism itemized in 177 cases [4]. Their order of frequency is roughly comparable with ours, but their percentages are slightly different. Headache, muscle cramps and Achilles tendon reflex were not taken into account in their study.

The 8 main symptoms that we selected in our study have both a subjective and an objective aspect: the patient complains of being cold and the physician feels the patients cold hands when shaking hands or when taking the patients blood pressure; the patients fatigue can be gauged by the hours he lies in bed during the day, and the number of sleeping tablets he takes at night; painful arthritis can be matched by palpation and auscultation of the articulations and by the number of NSAID tablets needed; headache is correlated with the number of tablets that the patient has to take; depression can be measured by the number of suicide attempts, or by the spells of melancholy during consultation; the degree of constipation is expressed by the number of bowel movements a week or a month, and the amount of laxative products used; muscle cramps can be quantized by the frequency, duration and potency of their attacks. The ninth most frequently noticed symptom was dryness of the skin.

Obese patients complain less frequently about cold, as they are protected by a layer of fat. On the other hand, one has to be aware of the difficulty of estimating the underlying cold in the presence of hot flushes in insufficiently oestrogen substituted menopausal women.

It is difficult for patients to compare their symptoms from one period of time to another. They usually only recognize an important improvement or deterioration over a very short period.

The Achilles tendon reflex has the outstanding advantage of being an expression of end-organ status, the target cells, the tissue response to changes in thyroid function, unobtainable by any other means than the ancient basal metabolism test and the basal temperature. The Achilles tendon reflex is absent in diabetes mellitus, chronic alcoholism with peripheral neuropathy, and after interventions in the region of the sciatic nerve. It is accelerated under caffeine use. It is prolonged by cooling of the calves [5]. When the Achilles tendon reflex is unreliable, the 24 hour urine free T3 remains helpful.

The use of coffee, tea, coke, cacao, tonic or alcohol accelerates the Achilles reflex, but the tendency to use these beverages is in itself a token of hypothyroidism which the patient tries to remedy. Beta-blockers, oestrogens, cotrimoxazole, psychotropes, lithium, amiodarone, and phenylbutazone decrease the T3 production by conversion inhibition from T4 into T3 in liver and kidneys.

Thyroid antibodies interfere with the production of thyroid hormones. It was also found that men seem to have a higher 24 hour urine T3 production than women.

Under treatment it is useless to determine T3 in 24 h urine before the desired dose is taken for at least two months. Conversely, it takes three weeks before a new clinical steady state is obtained after stopping treatment.

The 24 hour urine free T3 test appears to be reliable, and is not influenced by binding globulins. A possible problem is the collection of the total voided urine. This can be controlled by the determination of the 24 hour excreted creatinine.

A patient, showing a score of 5/16 or more of the main symptoms, with a 24 hour urine free T3 of 1400 pmol and less, is likely to have hypothyroidism. If a patient under maximum treatment still presents with a score of symptoms of 5/16 or more, drug compliance being certified, unsatisfactory intestinal absorption or inactivity of the drug has to be suspected.

The determination of free T3 in the 24 hour urine has a far better correlation with the clinical thyroid status of a patient than any other classical test. The determination of free T3 in 24 hour urine collection provides a logical and practical answer to the many clinicians who are anxiously looking for laboratory confirmation of their clinical diagnosis in thyroid disease.

In a study recently undertaken in 80 clinically hypothyroid patients [6], a group of investigators saw in only 6% of their clinically diagnosed hypothyroid patients a corroboration of their clinical diagnosis by a serum free T4 below the classical reference values, and in only 5% of their hypothyroid patients a confirmation of their clinical diagnosis by TSH values above the classical reference values.

Other investigators didnt, and any correlation between their symptoms score and TSH in 50 overt hypothyroid patients [7].

The correlation presented in this study between our symptoms score and the 24 hour urinary free T3 is about 0.55 (R2 5 0.32).

Under treatment, TSH measurements are of little value [8]. Under long-term treatment, even a third generation TSH-test drops to undetectable values. In comparison with the 24 hour urine free T3 we consider TSH a poor indicator of the thyroid status.

In secondary and tertiary hypothyroidism the determination of TSH is, of course, useless. But conversely, even under treatment with natural desiccated thyroid (T3 1 T4), the level of 24 hour urine free T3 continues to correlate closely with the patients clinical status. The explanation is that TSH is grossly in feedback with serum T4 only, not so much with serum T3, while the patients wellbeing depends on the free T3 that is disposable inside the cells. As hypothyroid patients are usually unable to convert inactive T4 into active T3, owing to a lack of 59 -deiodinase in the liver and kidneys, the administration of T4 can eventually correct the serum TSH level, but rarely provides the patient with the T3 needed to be relieved of his symptoms.

The determination of 24 h urine free T3 will prevent patients, suspected of hyperthyroidism, based on a low TSH rather than on clinical ndings, from being treated unnecessarily with thyroidectomy, radioactive iodine or thyreostatics.

CONCLUSION:

The 24hour urine free T3 test seems to be a reliable test, more accurate than the serum T4, serum free T4 and serum TSH test in the diagnosis of thyroid diseases and their follow-up inder treatment. It correlates well with the clinical status of the patient, and is not influenced by binding globulins. A series of 8 main symptoms can be used as an efficient tool in the discovery of thyroid disease.

(The 8 main symptoms are listed as: Constipation / Muscle Cramps / Depression / Headache / rheumatoid / Fatigue / Cold, Dryness of the skin the Slow Achilles Tendon Reflex being a sign)