Medical Mystery Number 1 (of a series)
Physicians have recorded many cases, over a period of many years, wherein the thyroid glands have overdeveloped as the direct result of tense and anxious living conditions. Sometimes the overdevelopment has not been visible (colloid goiter condition) and sometimes the goiter does become visible. Quite often the irregularity disappears with sufficient rest, but the underlying condition has never been extensively sought and is still an enigma to medical men. The simplicity of the mechanism causing it is unbelievable, and the exact nature of it is so demonstrable that any experimental animal suffices for proving.
Acetylcholine is the substance which is the chemical connective between nerve cells, between nerve and muscle, between nerve and gland. It is a most important chemical, because without it there can be no organic synchronization. It has been shown that it is manufactured in the animal body, and also that it breaks down in the animal body.
Disregarding the other products of the breaking down acetylcholine, consider the nitrogen compound which results in the process. Trimethylamine (a simple, and supposedly non-poisonous ptomaine, employed at one time against pneumonia without any particular reason) is produced, one molecule for each of acetylcholine broken down. In it the valence of nitrogen is different, from that in the original compound. Tma is partly excreted in the urine, giving rise to a part of the ammoniacal odor. However, it has functions far more important than this one.
The amount of Trimethylamine dissolved in the bloodstream aids in the regulation of the activity of the thyroid gland. As the amount of the substance in the bloodstream increases the thyroid increases its secretion of thyroxin.
Excessive nervousness and anxiety puts an extra load upon the entire body, particularly manifesting through nervous condition and glandular balance. As the effects of high-pressure living show up in people with susceptible thyroids, the bloodstream shows higher concentrations of trimethylamine (this constitutes an important portion of the non-protein nitrogen found in urine). As the trimethylamine concentration rises, lack of glandular synchronization and nerve effectiveness appears with listlessness and extreme lack of energy. This is made worse by the fact that it comes about through gradual exhaustion of the iodine content of the thyroid gland, so that chlorine (or bromine if present from sedatives) must be employed by the gland instead of iodine in the making of thyroxin. Thyroxin without enough iodine content becomes less and less effective as iodine percentage decreases. Heart disturbances show up, and as the trimethylamine level rises, the thyroid condition passes from the non-visible "colloid" goiter to apparent overdevelopment.
If a rat weighing one-half pound is fed four-tenths of a grain per day of trimethylamine hydrochloride for a period of three weeks to one month, the resulting overdevelopment of the exhausted thyroid can be easily seen and felt. In the case cats are used for the experiment, eight-tenths grain per day is necessary for the same period of time, or occasionally a little longer. The greater sensitivity of man to the substance makes the average dosage necessary to bring about human goiter three grains daily for an adult.
The writer's work has shown that the production of thyroxin is definitely dependent upon the destruction of acetylcholine and the liberation of trimethylamine into the plasma. Just as there are many different individual thyroid balances (as many as there are living individuals) so there are very different degrees of trimethylamine production. As the individual tires, the amount of this substance in the blood increases, and the thyroid endeavors to "increase the spark" so as to maintain activity, unless the individual relaxes completely or sleeps, so as to allow the acetylcholine-trimethylamine balance to be reestablished
Trimethylamine is like ammonia except that each hydrogen of the ammonia molecule is replaced with a methyl group (CH3). Since the use of ammonium chloride (corresponding to trimethylamine hydrochloride) does not cause thyroid sensitivity as the other compound does, it is demonstrable that the ptomaine and not the ready accessibility of chlorine to the gland from the compound is the responsible factor. Although the mass action of large amounts of chlorine or bromine do affect the thyroid, they do not ordinarily harm the gland in normal systemic concentrations.
It is possible to show that the ptomaine (trimethylamine) is actually employed by the thyroid gland in the manufacture of the organic portion of thyroxin.
As low a concentration as 1 part t.m.a. in ten-thousand of water, by inducing thyroid activation, causes many animals, even the lower forms such as frogs, to enter the mating season at times of the year when they will not breed at all, ordinarily.
When the general reserves of the body, including the amount of iodine stored in the thyroid, are low, systemic condition is much more favorable to the breakdown of acetylcholine, sensitivity to stimuli is high, and the mating instinct is strongest. So nature takes advantage of the lower iodine reserve predominant at early springtime, and many creatures answer the procreative tendency. This is as true of the human being as it is of the lower animals. It is the chemical background for the statement that in the Spring a young man's fancy turns to what the young ladies have been thinking about all Winter. Some say this means new clothes, but that is only a side issue with all creatures, new plumage being favored in response to the powerful mating urge.
The question of how the thyroid tends to become exhausted during the winter months will be discussed in detail in Medical Mystery Number II.
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