Popular Science Monthly/Volume 51/August 1897/The Thyroid Gland in Medicine
|THE THYROID GLAND IN MEDICINE.|
IN the past few years a remedy has been discovered for certain conditions hitherto regarded as incurable, which is certain in its action, and which for the beneficence of its results stands unrivaled in therapeutics; and, since from the infrequency of the diseases which it cures but little is known of this agent outside of the medical profession, it has appeared to me that a short description of the development and application of the thyroid treatment, one of modern medicine's greatest achievements, should prove of interest to any one who cares to observe the advances of medical science. The task is the more pleasant from the fact that the use in medicine of the thyroid gland of animals is a logical conclusion from adequate premises, and because the thyroid forms one of the few medicinal agents in our possession which are not given on purely empirical grounds.
It is a generally familiar fact that the majority of drugs are prescribed because medical history records that, for some unknown reason, they have proved effectual in the diseases in which they are administered, though why they should do so remains unexplained. In certain conditions mercury has a specific action, the nature of which is absolutely unknown. Quinine had cured the Countess Chinchon (and hence the name cinchona) of her ague centuries before a clever Frenchman discovered that malaria resulted from the activity in the blood of a vegetable parasite on which Peruvian bark exerts a restraining influence.
So it is with most of the remedies which the physician employs: he uses them because experience has shown that they will do good in the conditions in which he prescribes them, although he has not learned why. But in the use of animal thyroid the physician knows that he has a sovereign remedy, and he also knows the reasons for the brilliant results of its proper application. To appreciate the philosophy of the action of this agent requires the understanding of a few facts in anatomy and physiology which relate to what the thyroid gland is and to what it does.
In man the thyroid gland lies deep in the neck, in front and at the sides of the windpipe, and is covered by skin and muscle; its deep situation renders it difficult to be felt in the living subject. The thyroid belongs to the class of glands known as ductless—that is, there is no canal or duct by which the secretions of the gland are carried out. Its function, like the function of the other ductless glands (the spleen, the thymus, and the adrenal bodies), is but imperfectly understood. I shall limit myself to saying that the presence of the normal thyroid gland is necessary for health, and that it is supposed that the secretion of the gland, which enters the blood-current directly, either neutralizes some poison which, from the ordinary processes of life, is circulating in the blood, or furnishes to the blood some substance which is necessary to it. When from any cause this function of the gland is interfered with, very characteristic symptoms result. It is only within recent years that it has been recognized that impairment of thyroid function can and does cause a definite group of symptoms which constitute a disease. These symptoms may occur when a tumor develops in the gland, and will be intensified if, when the tumor is removed, much of the gland substance is destroyed.
But the most important disease of the gland itself, which is insidious, chronic, and progressive, is myxœdema. This affection is a chronic inflammation of the thyroid gland, by which the secreting structure is gradually destroyed, and which consequently deprives the patient of the good services which are rendered by a normal gland. In many respects myxœdema resembles Bright's disease, and it was some time after the first description of it by Sir William Gull before it became established that the affection depended upon the impairment of function of the thyroid gland, and not upon disease of the kidney. The most prominent symptom of the disease, and the one from which the name is in part derived, is an œdema or swelling, which, unlike the œdema of Bright's disease, does not pit on pressure. This œdema is most prominent in the face, and it is there that it begins, although later in the disease it may extend to the hands and feet, and thereby increase the general weight of the body. The lips are thickened, the nose becomes large and flat, and the eyelids are swollen. Owing to the swelling of the tongue and throat, the character of the voice may be changed. The skin is dry, rough, and peculiarly pale; the hair falls out—a symptom particularly noticeable in the eyebrows—the teeth become poor and the nails brittle. The pulse is slow, the heart is weak, and the temperature is almost always below the normal. Neuralgic pains are of common occurrence in myxœdematous patients, and cold weather is very disagreeable to them, probably on account of their low body temperature. The muscles are weak, especially those of the head and neck, and all muscular movements are slowly performed. The mind becomes dull and apathetic; there is usually developed irritability of temper. Hallucinations or perverted sense perceptions are not at all uncommon, and occasionally the affection terminates in insanity. These patients are peculiarly sensitive as to their own appearance and to the attention which it attracts, and consequently shun society; and for this reason partly, and partly because of their muscular weakness and subnormal temperature, they "like nothing so well as staying quietly in the house. The onset of the disease is gradual and its progress is slow, ordinarily extending over a period of several years. It most frequently occurs in women of middle age. Altogether myxœdema, although not a direct menace to life, makes the victim of it very uncomfortable and unhappy.
The appearance of a person suffering from advanced myxœdema is so characteristic that when one has seen a case there is usually no difficulty in recognizing another. In the earlier stages, however, when the disease is beginning, its diagnosis may be difficult or temporarily impossible.
Myxœdema is not a common disease in this country, and until five years ago was regarded as incurable. But as physicians become more familiar with the condition, which after all has only been recognized for about twenty years, and more especially as the possibility of curing it becomes more widely known, it is altogether probable that we shall find the disease less rare than we have been led to suppose.
The series of experiments which led to the employment in this disease of the thyroid glands of animals resulted in discoveries so complete and definite that it became possible to predict that the thyroid treatment of myxœdema would be a success. Before Sir William Gull described the affection and claimed for it a place of its own among the list of distinct diseases, it had been regarded as a variety of Bright's disease. But to the trained eye the resemblance of myxœdema to Bright's disease was too superficial to be satisfying; and, furthermore, when these patients died their kidneys, which would have shown disease changes if they had been responsible for the symptoms observed in life, were found to be normal. So the first step forward in our knowledge of the disease was the establishment of the fact that the seat of the trouble was not in the kidneys; it was not discovered until later that it was in the thyroid gland. This discovery came about from several sources.
It was observed by physiologists that animals from which the thyroid gland had been removed developed a condition of œdema and stupidity; and several surgeons reported that patients from whom the thyroid gland had been removed by operation for various causes developed symptoms almost identical with those of the cases which had been regarded as examples of Bright's disease, but in whom the kidneys were found nearly normal.
This experimental evidence was amplified by the work of pathologists who, in their examination of all the organs of persons dead with myxœdema, found that there existed constant disease in the thyroid, so that it became established beyond doubt that these symptoms, which were so much like those of Bright's disease, were in reality due, not to the ordinary causes of Bright's disease, but to a chronic inflammation of the thyroid gland—a process which resulted in the diminution or loss of the function of the gland, and a consequent deprivation of the secretion which it was intended to supply.
The symptoms which ensued after extirpation of the thyroid gland, whether in man or in the lower animals, received the name of cachexia thyreopriva, or operative myxœdema; when the condition occurred independently of such operations—i. e., from primary disease in the gland—it was called myxœdema; but although the pathology of myxœdematous conditions thus became established, it was a long time before it became known how they could be cured; and again it was due to the ingenuity and observation of physiologists and surgeons that it eventually became possible for the physician to apply a form of treatment which has proved curative for myxœdematous conditions of whatever origin.
It occurred to physiologists that if another thyroid could be made to grow beneath the skin of an animal whose own gland had been removed, the new thyroid might assume the functions of the one which was gone; and surgeons conceived the same idea for patients from whom the thyroid had been removed at operation. This was accordingly tried: physiologists grafted sheep's glands in monkeys whose own thyroid they had removed experimentally; and surgeons put sheep's glands beneath the skin of patients who had been operated upon on account of thyroid disease. Although these procedures were only partially successful, they were the beginnings which led to the ultimate establishment of the thyroid treatment. The results of these graftings were beneficial for a time, but as the transplanted thyroid could not be made to accommodate itself to its new home, the effects soon wore away and the myxœdematous symptoms returned. The temporary benefit, however, was so pronounced that it was evident that the disease had in some way been influenced by the grafted thyroid. Since the gland at the time of its transplantation was full of its normal secretion, but could not be made to secrete further after grafting, it was inferred that the beneficial influence was solely due to the thyroid juice which the grafted gland contained. So it became evident that the successful treatment of myxœdematous conditions required an uninterrupted supply of thyroid secretion. It was not until 1891 that Dr. G. R. Murray drew this conclusion, and presented at a meeting of a medical society in England a woman with myxœdema whom he said he intended to treat by subcutaneous injections of the extract of the thyroid gland of the sheep. When about six months later he showed the same patient, improved in every way, the success of the treatment was established.
The success which followed this experiment was so immediate and complete, and was so speedily substantiated by physicians the world over, that thyroid therapy at once became the recognized means of treating myxœdema and allied conditions.
The results of the treatment are very striking; the œdema rapidly disappears, leaving the skin soft, smooth, and moist; the
|Fig. 1.—Myxœdema. Before treatment.||Fig. 2.—Same patient after treatment.|
mental dullness gives way to cheerfulness and hope; strength is returned to the weakened muscles, and the patient becomes once more, to all appearances, a normal individual. A large number of cases of myxœdema have been recorded as cured by thyroid feeding, and these reports are usually accompanied with photographs of the patient as he appears before and after treatment, which present most striking contrasts. Through the courtesy of Dr. John Woodman, of New York, I am able to give the reproductions of the photographs (Figs. 1 and 2) of a case successfully treated by him. A common history of the early cases treated in this way is somewhat as follows: A woman has had myxœdema for years, and has been told by many physicians that her condition is incurable, and she is indifferent and skeptical as to the value of the treatment proposed for her. In a few months it is with difficulty that she can be recognized as the same person. The swollen, pallid, stupid face is gone, and in its place are red cheeks and the pleasant expression of a healthy woman. She can walk several miles a day, sleep well, has a good appetite, and enjoys life.
Such is the history of myxœdema and how it came to be treated by the thyroid gland of animals. Therapeutics can show no more brilliant results than these.
When myxœedema occurs in infancy or childhood it is called cretinism. The word "cretin" will recall to the minds of most of my readers visits to Switzerland or to the eastern parts of France, where these queer little dwarfs are so common. Goitre is also, curiously enough, frequent in these localities. But few are aware that we, here in America, possess cretins of our own. In the cretinous regions of Europe, where so many of the inhabitants are afflicted with the disease, it is called endemic or peculiar to the country. In America it occurs only occasionally, and not with any geographical regularity, and so such cretins are called sporadic. Now, sporadic cretinism with us is certainly a rare affection; but as the condition becomes more familiar to physicians, and as the inmates of our own idiot asylums are more carefully examined, it is possible that it will be found that cretinism, like myxœdema, is less rare than had been suspected.
The absence or disease of the thyroid gland produces much the same symptoms in the child as in the adult; the most striking difference is due to the fact that in the child development of the body and brain is interfered with, so that cretins are generally dwarfs, and the failure of mental development results in a condition closely allied to idiocy. These idiotic dwarfs are very repulsive to look at. They have large heads and necks and thick lips, through which protrudes the clumsy tongue. They have few or no teeth, and the swelling of the throat renders the voice indistinct. The nose is large and flat, and the swollen eyelids partly cover eyes which are frequently crossed. The limbs are swollen and often incapable of service; the skin which covers them is hard, rough, and thick. Cretins are always short, and may never grow taller than a normal child of two or three years. They never attain a high degree of intelligence, and most commonly are idiots with only the power to comprehend the simplest things of daily life, and with a vocabulary limited to a few words.
There are some differences between endemic and sporadic cretinism, and what follows applies only to sporadic cretins.
What has been said concerning the treatment of myxœdema by thyroid feeding may be repeated for sporadic cretinism. The changes which result from the thyroid treatment of cretins. owing to their stunted bodies and vacant minds, are even more astonishing than those described for myxœdema; for in cretins, not only do the œdema and other general symptoms disappear, but the dwarf begins to grow, and the idiot to show signs of intelligence. One patient who, at the beginning of treatment, was sixteen and a half years old and only thirty-three and a half inches in height, and in whom no growth had occurred in fourteen years, grew four and three quarters inches in six months;
|Fig. 3.—Sporadic Cretinism. Before treatment.||Fig. 4.—Same patient after treatment.|
another, sixteen and a half years old and twenty-nine and a half inches tall at the beginning of treatment, increased six and a half inches in height in six months. Under treatment the teeth begin to grow, and the facial expression and the whole appearance of the patient are radically changed. The patients soon become more intelligent and appreciative of their surroundings, and many begin to talk and to understand what is said to them. How striking may be the improvement in the general appearance is shown by Figs. 3 and 4, which are reproductions of photographs of a little patient treated by Dr. J. C. Carson, superintendent of the Syracuse Institution for Feeble-minded Children.
That the results will be permanent, and that these idiotic children will become, under the influence of the thyroid treatment, intelligent men and women, it is as yet impossible to say.
The occurrence, in the formative period of infancy and childhood, of a disease which attacks fundamentally nutrition, development, and growth, has much more disastrous effects than when its appearance is delayed until the organism has reached maturity.
And while it is possible that the removal of causes inhibitory to growth may result in a gradual return of developmental processes, the thyroid treatment of infantile myxœdema has in no case been carried out for a sufficient length of time to permit the assertion that such will be the case. In no case is treatment reported to have lasted more than three years, and in few cases is it said that the patient is in all respects cured; but from the fact that in nearly all of the cases treatment was not instituted until the child was several years of age and had developed but little or not at all for a considerable length of time, several years would be necessary, by the natural processes of development, for the complete re-establishment of normal growth.
Although data sufficient to justify positive assertions are lacking, it seems entirely in the range of possibility that if the treatment of sporadic cretinism were begun at the outset of the disease, before growth was seriously interfered with, it would permit the proper development of the child without myxœdematous symptoms as long as the thyroid was administered.
From the consideration of the history of myxœdematous conditions it will have been seen that all this treatment promised to do was to supply to the body the necessary substance which the thyroid gland was no longer able to produce. It never undertook to supply a new thyroid gland; and the disappearance of the symptoms of myxœdema under the thyroid treatment means that the necessary secretion is being artificially supplied, and not that the function of the gland has been restored.
Consequently, any one in whom the activity of the thyroid gland has been lost, whether it be by myxœdema, or operation which has induced the condition of cachexia thyreopriva, must continue the use of the thyroid glands of animals for the remainder of life. Dr. Murray's original case is still taking thyroid, and after five years remains well.
The therapeutic use of the thyroid has now been tried in many other conditions with varying success. From its efficacy in reducing the size of ordinary goiters it has to a great extent supplanted the knife in the treatment of that condition. Recent reports from Germany would seem to indicate that it exerts a beneficial influence upon the development of children who are physically or mentally backward, although they have none of the characteristic symptoms of cretinism. Its power to reduce excessive fat is becoming very widely known, and when properly used it certainly is a valuable agent for this purpose. In many diseases it may prove to be of service, though, aside from its use in myxœdematous conditions, exactly what place in the materia medica should be assigned to it, it is as yet impossible to say. The gland is obtained chiefly from the sheep, and is usually administered in the form of a dried powder or in tablets. Alarming symptoms may occur as a result of overdosage; such symptoms consist in too rapid loss of weight, or feeble heart action, or lowering of the temperature; they usually subside when the remedy is stopped. It should be remembered, however, that it is a mysterious and powerful agent, by no means destined for indiscriminate use.
In conclusion, it may be said that the introduction into medicine of the thyroid gland is a logical conclusion from adequate premises. It resulted from scientific experimental and chemical study by trained and skillful workers, and it has nothing in common with the largely advertised "organic extracts," which are false in theory and worthless in practice.
Animal thyroid is by no means a cure-all, and even in myxœdematous conditions which have existed for many years it may be unable to repair the ravages of the disease; but it has shown itself, when appropriately applied, to be among the most unfailing therapeutic agents in our possession.
- Read at Saratoga, September 2, 1896, before the American Social Science Association.