Medical Surgery study guide - test 3

E. Thyroid disorders: hypo/ hyper, medications, labs, and treatments – Surgery, radioactive iodine. • Thyroid gland o Principal actions  Stimulation of energy use  Stimulation of the heart  Promotion of growth and development • Thyroid gland is all about metabolism o Hormones secreted  T – 4 thyroxine  T – 3 triiodothyronine • T3, t4 influence heart and increased levels can causes palpitaions  Calcitonin • Works with the parathyroid gland to manage calcium levels  Iodine is necessary for production of thyroid hormones • Low iodine in diet can result in hypertrophy of gland – simple goiter o The goiter itself doesn’t tell if the patient has hyper or hypothyroidism  Physiological Role of the Thyroid Hormones • They have a diffuse effect and do not seem to have any specific target organ o Negative Biofeedback controls the thyroid system  When too much of the hormone is present, biofeedback slows down the release  When too little, the release is sped up  There are 3 levels of Neg. biofeedback • When T3, T4 are low: o 1. Hypothalamus recognizes low levels, releases TRH o 2. TRH stimulates the anterior pituitary gland to release TSH o 3. TSH stimulates the thyroid gland to increase production of T3, T4 • When T3, T4 are high: o 1. Hypothalamus recognizes high levels, stops or slows down release of TRH o 2. Anterior pituitary will then stop/slow down release of TSH o 3. Thyroid will then stop/ slow down release of T3, T4 • Hypothyroidism o Not enough production/release of T3, T4 o Slow metabolic rate o More common in women than men o Deficiency of thyroid hormone causes:  Myxedema: face swelling  Cretinism • Occurs in children and can lead to mental growth deficiencies o Pathology  Primary hypothyroidism • Caused by destruction of thyroid tissue or defective hormone synthesis • Most common cause in U.S is atrophy pf thyroid gland o Atrophy occur after autoimmune disease such and hyperthyroidism like graves and hasimoto  Secondary hypothyroidism • Caused by pituitary or hypothalamic dysfunction (↓ TSH or TRH) o Etiology  Iodine deficiency – most common cause worldwide  Atrophy of the gland  Treatment for hyperthyroidism  Drugs • amiodarone (Cordarone) (which contains iodine) and lithium (which blocks hormone production)  Cretinism if occurs in infancy • Caused by thyroid hormone deficiencies during fetal or early neonatal life. • All infants in the United States are screened for decreased thyroid function at birth. o Clinical Manifestations  Regardless of the cause, hypothyroidism has systemic effects characterized by a slowing of body processes.  Manifestations vary depending on the severity and the duration of thyroid deficiency, as well as the patient’s age at the onset of the deficiency.  The onset of symptoms may occur over months to years unless hypothyroidism occurs after a thyroidectomy, thyroid ablation, or during treatment with anti-thyroid drugs.  Cardiovascular system • ↓ Cardiac contractility and output • Angina, heart failure, myocardial infarction • Anemia o Erythropoietin levels may be low or normal. Because the metabolic rate is lower, oxygen demand is reduced. • Cobalamin, iron, folate deficiencies o May cause patient to bruise easily • ↑ Serum cholesterol and triglycerides o Can cause coronary atherosclerosis  Respiratory system • Low exercise tolerance • Shortness of breath on exertion  Myxedema o Physical swelling of skin and subcutaneous tissue o This edema causes puffiness, facial and periorbital edema, and a masklike affect. o Individuals with hypothyroidism may describe an altered self-image related to their disabilities and altered appearance. o Myxedema coma – Medical emergency  Impaired consciousness or come  Precipitated by infection, drugs, cold, trauma …………………………CONTINUED…………………………..