Journal of the Amer. Inst. of Homoeo. May, 1954.
Radio – Active Iodine Uptake and Excretion – In hyper – thyroidism, radio – active iodine is picked up by the thyroid more rapidly and is excreted in the urine more slowly than in normal subjects and therefore the determination of a tracer dose concentrated by the thyroid over a given period of time will often be a useful index of the level of thyroid activity. The simplest method is to estimate the fraction of the given dose in the thyroid and urine respectively during a 24 hour period of time.
The normal subject will concentrate from 25 to 40 per cent, a hyperthyroid individual 40 to 80 per cent, a myxedematous patient 0 to 25 per cent of the radio – active iodine in the thyroid, while the corresponding percentages for the urine will be 25 to 40, 10 to 30 and 50 to 70.
In the treatment of the thyrotoxic individual, psychotherapy with an effort to regulate the patients form of living is most important. Rest, both physical and mental, is necessary. Iodine in small doses may act to supply the relative deficiency of iodine present in hyperthyroidism, thus enabling the thyroid to manufacture thyroid hormone with less expenditure of energy.
Iodine may act through interference with the enzymic process responsible for the formation of thyroid hormone. In these cases the dosage must be larger and range from 10 to 75 mgs. daily. With this amount of iodine, the manufacture of thyroid hormone is decreased. Its retention within the colloid of the thyroid a acini is increased, at least temporarily. However, these large doses must not be continued indefinitely.
A third way in which iodine is believed to work is in its suppression of formation of thyroid hormone by the anterior pituitary. Large doses of iodine are used pre – operatively in the preparation of the patient for surgery. Usually these large doses should be continued for not over a three weeks period.
The anti – thyroid drugs which we use are propylthiouracil, methylthiouracil and Tapazole, the latter is a 1 – methyl – 12 – mercapto – imidazole product made by Lilly. The last is less toxic than the other two. A comparison of the dosage for control of the cases is 350 mgs. of both proplythiouracil and methylthiouracil and 15 to 25 mgs. of Tapazole daily. These drugs effectively control the thyrotoxic state, but it is necessary, in preparing a patient for surgery, to use iodine in the form of Lugols solution, from 5 to 15 drops three times a day for a period of two weeks in order to increase the firmness of the gland. These drugs will reduce metabolic rate within three to six weeks.
The purpose of surgery in these toxic case is to reduce the amount of the secreting gland. Operations is definitely indicated in toxic nodular goiters. The same regime is used in the exophthalmic type of goiter.
Radio – active isotopes, particularly I 131, have been used during the last several years. The dose of 100 micrograms per 1 GM of estimated thyroid tissue will be sufficient to control toxicity. This dose is repeated at two months intervals. This form of iodine therapy is well – suited for the exophthalmic type of goiter but rarely satisfactory for the control of the toxic nodular goiter.
In the preparation of our thyroid patients, for many years we have been using intravenous administration of 10 percent glucose solution in water for three days pre – operatively. This seems to decrease materially the liver damage which was the primary cause of thyroid crises which formerly were encountered in thyroid surgery.
Carcinoma of the Thyroid Gland – Statistics vary as to the percentage of malignancy in the thyroid. McGavacks figures show 22 per cent of all hospital admissions for thyroid disease were malignant and 6.6 percent of all admissions for nodular goiters were malignant. These figures vary greatly with different observers. Malignancy of the thyroid is most often discovered between the fifth and seventh decades of life. The majority of cases are in females. The papillary type of adenocarcinoma represents 30 of all thyroid carcinomas. This type is of low grade and only slightly radio – sensitive.
The Fetal Type of Carcinoma comprise 40 to 50 percent of all carcinomas of the thyroid. These lesions arise from the median anlage and represent forms from the embryonal solid tumors to the adult alveolar types showing marked cystic degeneration with or without calcification. These usually occur between the ages of 35 and 50.
Adenocarcinoma with Hurthle cell change are relatively rare lesions. They behave like adenomas or adenocarcinomes. The cells of these tumors bears a close resemblance to those of the liver and the adrenal cortex. They are compactly arranged to form small alveoli. The tumor may be discrete and well encapsulated or diffuse and invasive.
The Small Round – Cell Type of Carcinoma is divided into the compact type and the diffuse. These cells have the appearance of lymphocytes. It usually occurs in individuals over 50, has a rapidly fatal course and is resistant to X – ray radiation.
The Giant – Cell Type of Carcinoma is characterized by sudden, rapid growth in individuals between 55 and 65 years of age and is usually fatal within six to eighteen months. This comprises 10 percent of all carcinomas of the thyroid. All these types of carcinomatous glands will usually be unilateral and are attached, by their invasive qualities, to the surrounding structures, vessels and contiguous nerves and skin. Due to their invasive qualities, most of these cases will have hoarseness and aphonia and other tracheal pressure symptoms.
Only one – eighth of patients with thyroid malignancy show hyperthyroidism. It is natural to see that as the pathological process invades the gland, there is destruction of its secreting cells.
Radio – active iodine in massive doses may be helpful and may prolong life in the papillary carcinomas. Doses as high as 1500 millicuries or more are given over a period of 2 to 3 years. However, the results with radio – active iodine in cancer of the thyroid have been disappointing, due largely to the fact that these tumors do not have sufficient pick – up of iodine.