Hypothyroidism

• An endocrine disease characterizedby inadequate amount of circulating hormone
• Low levels of T3, T4, and thyroxine

• Serum TSH level
• Serum Free T4
• Serum T3
• Serum T4
• T3 Resin Uptake Test
• Thyroid Antibodies
• Fine - needle aspiration biopsy
• Thyroid scan, radioscan, or scintiscan
• Serum thyroglobulin

• The single best screening tool for thyroid function in outpatients because of its high sensitivity
• High TSH - hypothyroidism
• Low TSH - hyperthyroidism
• Used to differentiate thyroid disease versus parathyroid disease
• Prefer to screen at 35 and every 5 years thereafter

• Direct measurement of FREE (unbound) thyroxine, the metabolically active fraction of T4.
• Used commonly to confirm an abnormal TSH result
• Not affected by protein binding - only if using dialysis method, not immunoassay technique

• Low T3 and T4 - hypothyroidism
• High T3 and T4 - hyperthyroidism
• Measures the total T3 and T4 level, which includes protein-bound and free hormone levels - so not as accurate.
• Any factor that alters binding proteins changes the T3 and T4 levels (such as: OCP, corticosteroids, phenytoin, salicylates)

• INdirect measurement of unsaturated thyroxine-binding globulin (TBG)
• Determines the amount of thyroid hormone bound to TBG and the number of binding sites - which provides an index amount of thyroid hormone already present in circulation
• HIGH binding site availability - thus T3 uptake is less than 25% - hypothyroidism
• LOW binding site availability - thus T3 uptake is greater than 35% - hyperthyroidism

• Usually used to test for thyroid autoimmune diseases
• Positive test - indicates presence of antibodies - Hashimotos (100%) and Graves disease (80%)

• Measures the rate of iodine uptake by the thyroid gland
• LOW uptake - hypothyroidism
• HIGH uptake - hyperthyroidism

• To detect malignancy of thyroid
• Usually, the INITIAL test for thyroid masses

Used to detect persistence or reoccurence of thyroid carcinoma

Identify IODINE medications or agents that may affect results

• Contrast agents
• Thyroid medications (synthroid, PTU, tapazole)
• Topical anesthetics
• Multivitamin preparations
• Food supplements
• Cough syrups
• Amiodarone (antiarrythmic)
• Estrogens
• Salicylates
• Amphetamines
• Chemotherapeutic agents
• Antibiotics
• Corticosteroids
• Mercurial diuretics

• Etiology - PRIMARY, SECONDARY, TERTIARY
• Age of Onset - CRETINISM, JUVENILE, ADULT HYPOTHYROIDISM

A hormone secreted by parafollicular cells of the thyroid gland; parcipates in calcium regulation

• Thyroid hormone
• Active iodine compound formed and stored in the thyroid
• Deiodinated in peripheral tissues to form triiodothyroxine (T3)
• Maintains metabolism in steady state

• Primary - THYROIDAL
• Dysfunction of the thyroid itself
• Commonly caused by thyroidectomy

• Secondary - PITUITARY
• Dysfunction of the anterior pituitary gland

• Tertiary - HYPOTHALAMIC
• Decreased stimulation of TRH/TRF from the hypothalamus that results in adequate TSH

• Thyroid deficiency at birth
• Infant unable to produce enough thyroid hormones

Most often caused by autoimmune thyroiditis (Hashimotos thyroiditis) - which affects their growth and development

Affects mostly WOMEN, age 60 or older

• Autoimmune disorder of the thyroid gland - causes hypothyroidism
• Immune system attacks the thyroid gland
• High levels of thyroid antibodies
• Most common cause of hypothyroidism in the US

• Hashimotos thyroiditis
• Atrophy of thyroid gland common with aging
• Therapy for HYPERthyroidism
• Radiation to the head and neck - for treatment of head and neck cancers, lymphoma
• Medications
• Iodine DEFICIENCY and EXCESS
• Ingestion of excessive goitrogens

• Lithium
• Anti-thyroid medications
• Iodine compounds

• Radioactive Iodine
• Thyroidectomy

• Soy products
• Cruciferous vegetables - broccoli, cauliflower, cabbage, brussel sprouts

• extreme fatigue
• weight gain - but with poor appetite because of slow metabolism
• constipation
• joint muscle pain
• slow movements
• decreased pulse (low heart rate)
• decreased temperature
• cold intolerance
• hair loss, brittle nails, and dry skin
• expressionless, masklike, apathetic
• anxiety, depression
• myxedema - puffiness in the face, hands, feet
• inadequate ventilation - severe
• elevated cholesterol, atherosclerosis, CAD - severe
• myexedema coma - MOST SEVERE
• abnormally sensitive to sedatives, opiod, and anesthetic agents - administer with extreme caution
• increased susceptiblity to infection
• increased risk for intraoperative complications

• Hypothyroidism in its most severe state
• Can be precipitated by: infection, drugs, cold, or trauma
• All of s/sx of hypothyroidism exacerbated
• Myxedema - characterized by masklike expression, puffy eyelids, hair loss in eyebrows, thick lips, and a broad tongue - because of an accumulation of mucopolysaccharides in these areas
• Subnormal temperature
• Hypotension
• Hypoventilation

• Goal is to restore patient to a normal metabolic state by replacing the missing thyroid hormones
• Synthetic levothyroxine (Synthroid or Levothyroid)
• Prevention of cardiac dysfunction - caution for ANGINA which could lead to MI - when giving levothyroxine it increases oxygen demand that wasn't there before because of the decreased metabolic demand; atherosclerosis needs to improve first. IF ANGINA OCCURS - d/c thyroxine administration and then cautiously administered at a lower dose
• Prevention of medication interactions - thyroid medications increase glucose levels, dig, anticoagulants. phenytoin (dilantin) and TCAs increase thryoid hormone effect. sedative hypnotics may further decrease metabolic function - be wary of respiratory depression.

• Modify activity - encourage patient to partcipate in exercise
• Monitoring physical status - monitor for response to therapy (gets better or worse?)
• Promoting physical comfort - provide blankets and extra clothing to deal with cold intolerance (even if the room is warm). DO NOT USE heating pads or electric blankets because of risk of peripheral vasodilation or risk of burns.
• Enhancing coping measures - inform patient and family that symptoms and inability to recognize are common. must teach symptoms.
• Home/Discharge teaching

• Cardiovascular - decreased HR. atherosclerosis may lead to angina and then MI.
• Respiratory - tends to be depressed

• Hypothermia
• Imbalanced nutrition: more than body requirements
• Activity intolerance related to fatigue and depressed cognitive process
• Risk for imbalanced body temperature
• Constipation related to depressed gastrointestinal function
• Deficient knowledge about the therapeutic regimen for lifelong thyroid replacement therapy
• Ineffective breathing pattern related to depressed ventilation
• Disturbed thought process related to depressed metabolism and altered cardiovascular and respiratory status