Hypothyroidism
Hypothyroidism may be caused by a number of factors including a reduction in hormone synthesis by the thyroid gland, thyroid gland ablation (surgery/radiation), deficient TSH, and peripheral causes (deficient T4 to T3 conversion, excess rT3, and thyroid hormone resistance).
The two most common causes of hypothyroidism are chronic lymphocytic thyroiditis (Hashimotos disease), an autoimmune form of thyroid condition, and iatrogenic causes (treatments for hyperthyroidism, such as thyroidectomy, Iodine 131 therapy, and antithyroid drugs).
Chronic Lymphocytic Thyroiditis (Hashimotos Disease)
- Commonly begins between the ages of 30 and 50 and affects women more often than men.
- Approximately 20% of patients have symptoms of hypothyroidism when first diagnosed, while for the majority, hypothyroid symptoms will follow the goiter.
- Other forms of autoimmune disease may exist with Hashimotos thyroiditis, such as Addison’s disease, rheumatoid arthritis, systemic lupus erthymatosus, Sjögren’s syndrome, and pernicious anemia.
Secondary Hypothyroidism
- When the pituitary gland gets smaller as a result of tumors, surgery, or radiation, it cannot produce enough thyroid-stimulating hormone (TSH), resulting in a hypothyroid state.
Tertiary Hypothyroidism
- Though rare, when there is a problem with the hypothalamus (trauma or surgery induced), this in turn affects the pituitary, resulting in a hypothyroid state.
Other Pathologies
Certain diseases that affect the connective tissue in the body (for example, sarcoidosis, amyloidosis, and scleroderma), can affect the thyroid gland as well. When these diseases reach the thyroid gland, they add tissue (typically connective tissue) which results in taking the place of thyroid gland tissue, and the thyroid gland looses ability to produce thyroid hormone.
Congenital Disease
Although rare, approximately 1 in 5,000 babies are born with a malfunctioning thyroid gland or no thyroid gland at all.
Postpartum Thyroiditis
Fluctuating thyroid function after childbirth is common (5% to 10% of patients in some studies). Thyroid inflammation may occur several months after childbirth, resulting in the development of clinical hyperthyroidism. In some patients, the hyperthyroid phase causes significant damage to the thyroid, resulting in the development of hypothyroidism.
Nutrition
Fasting or deficiency of vitamin, minerals or amino acids can lead to hypothyroidism. Conversely, excess consumption of certain foods, known as goitrogens, can induce hypothyroidism. These include brassicas (cabbage, kale, brussel sprouts, mustard, cauliflower), rutabagas, peanuts, turnips, peaches, pears, spinach, and soy.
Deficiencies leading to Hypothyroidism by Impairing T3 to T4 Conversion
| Trace Minerals | Selenium, iodine, iron, zinc, |
| Vitamins | A, B2, E |
| Amino Acids | Cysteine, tyrosine |
| Energy Compounds | Glucose ATP, NAD, NADH-O2 |
| Nutrition | Fasting, starvation, anorexia, protein or calorie malnutrition, lack of hydrocarbons, lack of fats (severe deficiency) |
| Hormones | GH, TSH, insulin, FSH, melatonin, prolactin |
| Environmental | Pesticides |
Excesses Leading to Hypothyroidism
| Trace Minerals | Calcium, lithium, copper |
| Nutrition | Nutrition |
| Hormones | Estrogen dominance, stress hormones such as catecholamines, ACTH, cortisol, vasopressin, angiotensin II, glucagon |
| Medications | Beta-blockers, propyl-thiouracil PTU, theophylline, clomipramiine, amiodarone, chemotherapeutic agents, Phenytoin, röntgen contrast products |
| Toxins | Alcohol, Digestive toxins such as cholera, botulinum, candida, cyanide, thiocyanate |
Other causes of impaired thyroid function
Pesticides, toxic metal exposure, stressors such as trauma, sleep deprivation, excess alcohol, grief and illness, and poor nutrition can all result in altered thyroid function.
Subclinical Hypothyroidism
Refers to patients who exhibit typical hypothyroid symptoms of cold intolerance and fatigue. They have normal levels of thyroxine, while slightly elevated TSH levels. Patients can also have normal thyroid tests and exhibit hypothyroid symptoms; this is identified as Wilson’s temperature syndrome. Subclinical hypothyroidism affects 20% of women over age 50, indicated by normal levels of T3, and T4, and mild elevated TSH.
Subclinical hypothyroid should be treated not only for symptomatic relief but also due to its close association with hypercholesterolemia and cardiac abnormalities.
Signs and Symptoms of Hypothyroidism
- Hypertension
- Bradycardia
- Coarse, dry hair
- Periorbital swelling
- Yellow skin due to elevated beta carotene
- Delayed relaxation of deep tendon reflexes
- Fatigue
- Cold intolerance
- Depression
- Weight Gain
- Weakness
- Joint aches
- Constipation
- Dry skin
- Hair loss
- Menstrual Irregularities
