Thyroid problems are split into four groups: goiter, hypothyroidism, hyperthyroidism and cancer. They all can present with their own unique profile of symptoms and laboratory findings that can help the clinician narrow down the diagnosis. Treatment for these problems can range from careful observation to surgical intervention, depending on the disease process and the stage at which it is discovered.
Goiter
Goiter refers to an enlargement of the thyroid gland, which can be diffuse, or multinodular. It is not limited to a specific disease process and occurs in patients who are hypothyroid, hyperthyroid and even euthyroid (have normal thyroid function). The most common cause of goiter is iodine deficiency, and its management depends on the clinical presentation. If the thyroid gland has been growing rapidly, neoplasm must be excluded; and if it exists with a hypo- or hyperthyroid state, the underlying problem must be addressed first.
Hypothyroidism
Hypothyroidism is the most common type of problem affecting the thyroid gland, and the symptoms are due to a decreased level of T3 hormone. The most common symptoms are dry skin, constipation, fatigue and menstrual cycle irregularities, along with weight gain, weakness and cold intolerance. Often the patient has lipid abnormalities as well as increases in the levels of certain enzymes, for example creatine kinase (CK), lactate dehydrogenase (LDH) and liver enzymes (AST), that will resolve with treatment. While the presentation can often be very subtle, it can also be very serious, in the form of myxedema coma. This syndrome has the above features in an amplified form, with additional symptoms like hypotension (low blood pressure), bradycardia (slow heart rate), altered mental status and hypothermia (decreased body temperature), and can result in coma and death.
Hyperthyroidism
Hyperthyroidism is due to either increased T3 hormone or stimulation of the hormone receptors on the thyroid and is characterized by increased function of the thyroid gland. The most common symptoms are fatigue, weight loss, sweating, heat intolerance, tremor and anxiety. Other symptoms include increased appetite and diarrhea; common complications if hyperthyroidism is left unchecked (such as in a subclinical scenario) include osteoporosis and atrial fibrillation (a type of cardiac arrhythmia). In fact, the risk for cardiovascular disease overall is increased with hyperthyroidism, which is why treatment is pursued vigorously; risks include myocardial infarction (heart attack) and congestive heart failure. In the special case of Graves disease, additional symptoms include protrusion of the eyes (exophthalmos) and nodules on the lower legs known as "pretibial myxedema." Thyroid storm can result, which is a sudden and severe flare-up of thyroid symptoms including tachycardia (increased heart rate), fever and delirious state of mind. This can be fatal if treatment is not implemented adequately.
Cancer
There are different types of thyroid cancer with their own prognosis and associated syndromes. Often symptoms include a neck mass that has been growing visibly, and in the case of medullary carcinoma, increased calcium levels. Calcium level increases because this tumor secretes the hormone calcitonin, although the levels are not dramatically higher than normal. Locally the growth can affect swallowing, impinge on the airway (making respiration difficult) and damage local structures such as arteries or nerves (e.g., the recurrent laryngeal nerve, causing hoarseness).
References
- "Textbook of Family Medicine;" R. Rakel; 2007
- "Williams Textbook of Endocrinology, 11th Edition;" H.M. Kronenberg, M.D. et al.; 2008
- "Endocrinology and Metabolism Clinics;" Hyperthyroidism; B. Nayak, S. Hodak; September 2007
