Patient will present as → a 43-year-old female with complaints of increased fatigue and a 10-lb weight gain over the last 2 months. She states that she "feels cold" all the time, has decreased energy, and is experiencing worsening constipation. She has also been having heavy periods. On physical exam, her pulse is 45/minute, her skin is dry and cold, and her eyebrows are thinned. You notice delayed deep tendon reflexes. Routine blood tests demonstrate a TSH level of 9.5 uU/mL (normal 0.35 to 5.0 uU/ml) and Thyroxine (T4), serum: 9.8 ug/dL (normal 5-12 ug/dL).
Hypothyroidism is a condition in which the thyroid gland doesn't produce enough thyroid hormone.
- The most common cause Hashimoto's thyroiditis which is an autoimmune-mediated form of hypothyroidism. The body’s immune system attacks the thyroid tissue, preventing the normal secretion of thyroid hormones.
- Labs: ↑ TSH and ↓ Free T4
- Thyroid hormone levels may be normal early in the disease. The TSH level will be elevated, though, and the thyroid hormone levels will begin to decrease as the disease progresses.
- In primary hypothyroidism, there is no feedback inhibition of the intact pituitary, and serum TSH is always elevated, whereas serum free T4 is low.
- In secondary hypothyroidism, free T4 and serum TSH are low (sometimes TSH is normal but with decreased bioactivity).
- Free thyroxine (T4)
- Many patients with primary hypothyroidism have normal circulating levels of triiodothyronine (T 3 ), probably caused by sustained TSH stimulation of the failing thyroid, resulting in preferential synthesis and secretion of biologically active T 3. Therefore, serum T 3 is not sensitive for hypothyroidism.
"Subclinical hypothyroidism occurs in the early stages of thyroid function inadequacy. The hypothalamic-pituitary axis recognizes falling serum T4 levels and increases TSH function accordingly. TSH, serum: 11.2 uU/mL (normal 0.5-5.0 uU/mL) and Thyroxine (T4), serum: 9.8 ug/dL (normal 5-12 ug/dL). Patients with the disease should be treated with thyroxine in the event of goiter, hypercholesterolemia, symptoms of hypothyroidism, or TSH levels > 20 uU/mL. "
Diagnosis of Hashimoto's is confirmed by antithyroid peroxidase (TPO) antibodies
- Anemia is often present, usually normocytic-normochromic and of unknown etiology, but it may be hypochromic because of menorrhagia and sometimes macrocytic because of associated pernicious anemia or decreased absorption of folate.
- Serum cholesterol is usually high in primary hypothyroidism but less so in secondary hypothyroidism.
Thyroid replacement hormone therapy
TSH levels are regularly performed (measured six weeks after initiation and any changes in dosing until normal levels are achieved) to measure the thyroid hormone levels and ensure that patients have reached a therapeutic dose of hormone replacement therapy.
- Thyroxine, adjusted until TSH levels are in mid-normal range
- Oral T4 ( L -thyroxine) (Levoxyl, Synthroid) is the preferred treatment and is given in the lowest dose that restores serum TSH levels to the mid-normal range
- Treatment should be continued through pregnancy.
Complications: Hashimoto encephalopathy, goiter, heart failure, depression, decreased libido, myxedema
Slowed speech and movements
- Weight gain
- Slowed speech and movements
- Dry skin
- Coarse, brittle, straw-like hair
- Loss of scalp hair, axillary hair, pubic hair, or a combination
- Dull facial expression
- Coarse facial features
- Periorbital puffiness
- Goiter (simple or nodular)
- Decreased systolic blood pressure and increased diastolic blood pressure
- Pericardial effusion
- Abdominal distention, ascites (uncommon)
- Hypothermia (only in severe hypothyroid states)
- Nonpitting edema (myxedema)
- Pitting edema of lower extremities
- Hyporeflexia with delayed relaxation, ataxia, or both
Male patients with hypothyroidism and excessive weight gain
Female patients with galactorrhea and menstrual disturbances secondary to hypothyroidism
Patients with hypothyroidism and decreased appetite, sleepiness, hair loss, and dry skin
Patients with untreated hypothyroidism who are subjected to an external stress
Free thyroxine (T4) assay
Third-generation thyroid-stimulating hormone (TSH) assay
Anti-thyroid peroxidase (anti-TPO) antibody assay
Antithyroglobulin (anti-Tg) antibody assay
All adults older than 50 years on a routine basis
Pregnant women, but not until the second trimester
Asymptomatic adults older than 40 years
Women older than 50 years who have one or more clinical features of the disease
- The American College of Physicians recommends screening all women older than 50 years who have one or more clinical features of disease
- The American Academy of Family Physicians recommends screening asymptomatic patients older than 60 years
- The American Association of Clinical Endocrinologistsrecommends TSH measurements in all women of childbearing age before pregnancy or during the first trimester
- The US Preventive Services Task Force concludes that the evidence is insufficient to recommend for or against routine screening for thyroid disease in adults (grade I recommendation)
Levothyroxine at a dose of 50-75 µg/day
Levothyroxine at a dose of 4 µg per kilogram of lean body weight as an intravenous bolus, with 100 µg administered 24 hours later
Desiccated thyroid at a dose of 15-30 mg orally per day
Liothyronine at a dose of 25 µg orally per day