Prognosis, Laboratory Investigations And General treatment Of Hypothyroidism
Living With And Diagnosing Hypothyroidism
A General Overview
Course and prognosis
The course of hypothyroidism is slowly progressive with fluctuations in thyroid function. Myxedema coma, ischemic heart disease or cardiac failure may prove fatal in some. Myxedema promptly responds to replacement therapy, but the condition recurs on cessation of medication. Delay in instituting treatment in children results in permanent retardation of mental faculties, even though the physical and sexual characteristics may recover to variable extent with medication.
- The basal metabolic rate (BMR) is low. Since low BMR occurs in many other conditions, this finding is not specific.
- Serum cholesterol level is raised above 300mg/dl in many cases of myxedema. In pituitary hypothyroidism, the cholesterol level is normal.
- Creatinine phosphokinase level is increased.
- I131 uptake by the thyroid is low
- Serum T3, T4, T3RU and FTI levels are all low.
- The TSH level is very high in primary hypothyroidism. It is low in pituitary or hypothalamic hypothyroidism. In hypothalamic hypothyroidism, administration of TRH leads to the production of TSH and increase in T4 and T3 levels.
- ECG shows slow rate, low voltage and ST and T wave changes.
- Immunological markers: Titres of antithyroglobulin and antimicrosomal antibodies are high, especially if the disease is of autoimmune origin.
- Photomotogram: This is an objective way of recording the ankle jerk. The prolongation of relaxing time is objectively demonstrated.
Living With And Treating Hypothyroidism
General principles of treatment
Principle of therapy is to replace the deficient hormones. The available preparations are:
- Dessicated thyroid 60mg tablets;
- Thyroxine (T4): 0.05-0.1mg tablets, and
- Tri-iodothyronine, 25 ug tablets. Dosage 0.1mg of T4, 25ug of T3 and 60mg of dessicated thyroid are equipotent.
L-thyroxine sodium is the drug of choice and should be employed for initial therapy. Dessicated thyroid has been abandoned in many centers, due to difficulty in standardization and loss of potency on storage. Tri-iodothyronine is used for rapid action in emergencies such as myxedema coma. In most of the cases, hypothyroidism rends to be permanent and therefore lifelong medication is required, with increase in the dose during periods of stress.
Treatment of Cretinism
The development of normal mental function in cretinism depends almost solely on the institution of treatment early in the neonatal period. Any delay in starting thyroid hormone replacement will lead to permanent disability. Therefore the need to make an early diagnosis cannot be overemphasized. Routine estimation of T4 and T3 in neonates is undertaken in many centers to exclude neonatal hypothyroidism. The prospect for normal mental development is poor if treatment is not started before the age of 1 year.
Infants require 0.05mg of thyroxine and in late childhood, the requirement may go up to 0.1- 0.2mg/day. The child’s growth and bone development should be monitored by regular clinical and radiological examination.
Uncomplicated myxedema: Most of the cases respond to 0.1- 0.2mg of thyroxine. In elderly patients, the initial daily dose should be less than 0.1mg. Higher doses may precipitate angina pectoris. Adjustments of dose to reach the optimum may be needed at monthly intervals. In elderly subjects, administration of propanolol 20mg thrice daily along with T4 is helpful in preventing angina.
Treatment of myxedema coma: Treatment of myxedema coma is a medical emergency. Coma is the result of a combination of factors such as heart failure, cerebral ischemia, hypothermia and hypothyroidism.
The drug of choice is T3 given intravenously in a dose of 20 ug and repeated after 4 hours. Simultaneously T4 0.1- 0.2mg is also given through a nasogastric tube. The body is gradually warmed in a hot bath. Hydrocortisone 100mg is also given intravenously 2-4 times daily. Adequate ventilation is maintained. Oxygen inhalation is beneficial. After recovery from coma, the thyroid function is assessed and lifelong therapy instituted.
© 2014 Funom Theophilus Makama