The thyroid is the gland located in front of the neck surrounding the "Adam's apple." It produces the thyroid hormones triiodothryronine (T3) and thryroxine (T4). T3 is the more active form. T4 is also partially converted to T3 when released in the blood stream. The thyroid hormones regulate metabolism throughout the body.

The pituitary gland in the brain also releases a thyroid-stimulating hormone (TSH) that regulates the production and release of thyroid hormones from the body. Additionally, there is a hormone made in the hypothalamus of the brain called thyroid-releasing hormone (TRH), which controls the release of TSH from the pituitary gland. A problem in the thyroid gland, pituitary gland, or hypothalamus can all result in low thyroid hormone,  Hypothyroidism.

Early symptoms:

1. Fatigue
2. Cold intolerance
3. Constipation
4. Muscle aches
5. Hair thinning
6. Depression
7. Weakness
8. Hoarseness

Examination:

1. Dry skin
2. Slow Heart Rate
3. Delayed return of reflexes

Later symptoms:

1. Weight gain
2. Constipation
3. Hoarseness
4. Slow speech
5. Leg swelling (edema)
6. Pale skin
7. Muscle Cramps
8. Absence of sweating
9. Shortness of breath
10. Menstrual periods stop
11. Increased menstrual bleeding
12. Milk secretion from breast
13. Deafness
14. Decreased sense of taste and smell

Examination:

1. Puffy eyelids
2. Puffy face
3. Yellow skin color
4. Thickened tongue
5. Thinning of eyebrows
6. Hard swelling of legs
7. Enlarged heart
8. Swollen abdomen (Ascites)
9. Extra fluid in lungs (pleural effusions)
10. Fluid around the heart (Pericardial Effusions)
11. Low core body temperature

Thyroid gland disease
Iodine deficiency
Hashimoto's Thyroiditis
Genetic thyroid enzyme defects
Medications
Food goitrogens
Peripheral resistance to thyroid hormone
Thyroid Cancer
Sarcoidosis involving the thyroid gland
Elevated 3rd generation TSH level (best test)
T4 level is low or below normal
Cholesterol may be elevated

Other findings may include: increased liver enzymes, Creatinine kinase, Prolactin, low Sodium, glucose, and hematocrit. Antimicrosomal and antithyroglobulin antibodies are high in Hashimoto's Thyroiditis

Chest X-Ray may show an increased cardiac silhouette or pleural effusions

Abdominal Ultrasound may show Ascites

MRI of the pituitary may show enlargement (due to hyperplasia -- it is trying to secrete more TSH to make up for low amounts of thyroid hormones being secreted by the thyroid)

Levothyroxine (T4) replacement. In elderly individuals, the starting dose should be low and increased slowly, so as not to precipitate any underlying heart disease.

Dose of levothyroxine is based on TSH levels

Myxedema Coma -- intravenous levothyroxine plus intravenous Hydrocortisone

Levothyroxine dose may need to be increased during pregnancy, or in patients taking Phenobarbital or bile acid binding resins.

Myxedema Coma this is a rare complication of severe Hypothyroidism. It is usually associated with hypoventilation (insufficient breathing) with Hypercapnia, hypoxia (low oxygenation), low core body temperature, Low Blood Pressure, and low Sodium. This is a life-threatening emergency.

Coronary artery disease -- thyroid hormone replacement may precipitate underlying heart disease (i.e., it uncovers heart disease). Therefore, elderly patients are begun at low doses of replacement hormones, and the dose is increased slowly.

Psychosis "Myxedema madness"
Infertility
Pregnancy  Hypothyroidism may cause a Miscarriage

 

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