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Thyroid Emergencies Heidi Chamberlain Shea, MD Endocrine Associates of Dallas Thyroid Trivia • Largest endocrine gland – 20 grams in adult – Each lobe • 2-2.5cm in width and thickness • 4cm in height – Isthmus • 0.5cm thick • 2cm height and width • Named for the relationship to the laryngeal thyroid cartilage – Resembles a Greek shield Thyroid Hormone Synthesis • Iodide trapping • Oxidation of iodide and iodination of thyroglobulin • Coupling of iodotyrosine molecules within thyroglobulin (formation of T3 and T4) • Proteolysis of thyroglobulin • Deiodination of iodotyrosines • Intrathyroidal deiodination of T4 to T3 Thyroid Hormones T4 T3 T4 ( Tetraiodothyronine ) T3 ( Triiodothyronine ) , Reverse T3 Goals of Discussion • Hypothryoidism – Clinical symptoms – Myxedema Coma • Definition • Treatment • Hyperthryoidism – Clinical symptoms – Thyroid Storm • Definition • Treatment Hypothyroidism Symptoms • Nervous system – Forgetfulness and mental slowing – Paresthesias – Carpal tunnel – Ataxia and decreased hearing – Tendon jerk slowed with prolonged relaxation phase • Cardiovascular – Bradycardia – Decreased cardiac output – Pericardial effusion – Reduced voltage on EKG and flat T waves – Dependent edema Hypothyroidism Symptoms • Gastrointestinal – Constipation – Achlorhydria with pernicious anemia – Ascitic fluid with high protein • Renal – Reduced excretion of water load • Hyponatremia – Decreased renal blood flow and glomerular filtration • Pulmonary – Responses to hypoxia and hypercapnia are decreased – Pleural effusions high protein • Musculoskeletal – – – – Arthralgia Joint effusions Muscle cramps CK can be elevated • Anemia – Normochromic normocytic – Megaloblastic • Pernicious anemia Hypothyroidism Symptoms • Skin and hair – Loss of lateral eye brows – Dry, cool skin – Facial features • Coarse and puffy – Orange skin • Carotene • Reproductive system – Menorrhagia from anovulatory cycles – Hyperprolactinemia • No inhibition of thyroid hormone • Metabolism – Hypothermia – Intolerance to cold – Increased cholesterol and triglyceride • Decreased lipoprotein receptors – Weight gain Myxedema Coma Diagnosis • Altered mental status – Decreased orientation – Increased lethargy – Confusion/psychosis – May be secondary to • • • • Stroke Medication effect Sepsis CO2 narcosis Myxedema Coma Diagnosis • Defective thermoregulation – Normal body temperature with sepsis • Age – Most are elderly • Decreased ability to compensate • Precipitating illness or event – Exclude pulmonary or urinary tract source – Trauma – Stroke – Hypoglycemia – Hypothermia – CO2 narcosis – Diuretics – Sedatives – Tranquilizers – Drug overdose Myxedema Coma Management • When in doubt, treat – Mortality 30-40% • ICU setting • Lab tests – TSH, T4, T3-uptake, Cortisol, CBC with diff and routine chemistries – Blood, sputum and urine cultures – WBC may not be elevated • Bands present of other concerning finding, empiric treatment is appropriate Myxedema Coma Management • Body temperature support – Poikilothermic – No aggressive warming • Vasodilatation= vascular collapse – Passive warming • Respiratory support – Intubation may be needed – If HCT <30%, transfuse • Provide adequate perfusion and oxygen carrying capacity Myxedema Coma Management • Cardiovascular support – Fall in blood pressure is ominous • Look for GI bleed, MI, over diuresis or iatrogenic vasodilatation • Endocrine support – Hydrocortisone 100 mg Q8 hrs • Treat possible coexisting primary or secondary adrenal insufficiency • Stop once cortisol level is confirmed to be normal Myxedema Coma Management • Thyroid hormone therapy – 300-500 ug IV Levothyroxine x1 – 50-100 ug IV Qday • Lower doses for smaller people or older at risk for cardiac events • IV to bypass poor absorption in the bowel – Alternately give T4 and T3 due to decreased T3 conversion • 200-300 ug T4 then 50 ug/day • 5-20 ug T3 then 2.5-10 ug Q8 hrs Myxedema Coma Management • Addition of Levothyroxine causes – Increase in cardiac index 1-2 days – TSH falls 32% in 24 hrs – Serum T3 levels increased on 3rd day – Reversal of blunted ventilatory responses 7 days Myxedema Coma Management • Obtain Free T4- 3 days after initiation of therapy to make sure it is increasing – Adjust to normalize value • Once tolerating PO can change to oral therapy – Increase IV dose by 40% for oral dosing • ie: IV 100 mcg then 140 mcg PO Hyperthyroidism Hyperthyroidism Symptoms • • • • • Nervousness/Anxiety Weight loss Increased hunger Heat intolerance Cardiac – Atrial fibrillation – Palpitations • Increased stool frequency • Decreased concentration • • • • • Weakness Fatigue Decreased sleep Irritablity Change in menstrual patterns • Infiltrative orbitopathy – Exopthalmos • Goiter – 20% elderly no goiter – 3% normal size Hyperthyroidism • Cardiac – Sinus tachycardia – 15% atrial fibrillation – Increased cardiac output 2-3 times normal • Nervous system – Diaphoresis – Tremor Hyperthyroidism • Increased metabolic rate – Increased blood flow to tissues by vasodilatation • T3 affects smooth muscle tone – Systemic vascular resistance is decreased by 50% • Decreased diastolic blood pressure • Increased rate and force of cardiac contraction – Increased erythropoietin = increased blood volume Hyperthyroidism Lab Tests • TSH • Free T4 – If done by RIA can be falsely elevated – Gold standard equilibrium dialysis • T4 and T3 uptake • T3 • Thyroid stimulating immunoglobulin (TSI AB) • TSH suppressed with increase in T3 and T4 Thyroid Storm Diagnosis • Decompensation of function due to symptoms – Hyperthermia – CNS effects • Delirium, psychosis, coma, seizure – Cardiac • Tachycardia • Heart failure • Abnormal rhythm – GI/Liver dysfunction • Jaundice • Diarrhea, nausea, vomiting and abdominal pain Hyperthyroidism Treatment • B-adrenergic blockade – Use cautiously in asthmatics and diabetics – Improves • • • • • Tachycardia Widens pulse pressure Decreases palpitations Anxiety Sweating – Propranolol • Some decrease in T4 to T3 conversion • 20-40 mg Q4-6hrs – Atenolol or Metoprolol • Longer acting Hyperthyroidism Treatment • Thionamide medications – Block the thyroid hormone synthesis by blocking organification of iodine • Propylthiouracil (PTU) – Blocks peripheral conversion of T4 to T3 in liver and kidney – 300-600 mg Q8 hrs • Methimazole (Tapazole) – 30-60 mg Q8hrs, BID or QD Thyroid Storm Management • • • • ICU setting Mortality of 20-30% Obtain thyroid function tests Load PTU oral 1000 mg x1 then 200-250 Q4 hrs. – Rectal administration • Use Tapazole 30 mg Q6hrs – Rectal administration • Side Effects – Rash, arthralgia, serum sickness, abnormal liver function tests and agranulocytosis • Sodium ipodate and iopanoic acid – Radiographic contrast agents – Potent inhibitors of T4 to T3 conversion – Structurally similar to thyroxine – 1 gram daily • Decrease T3 in 24-48 hours • Continue for 7-14 days Thyroid Storm Management • Inorganic iodine – Blocks thyroid hormone release – Lugol’s solution (8 drops) or saturated solution of potassium iodide (SSKI) (6 drops) Q6 hrs. • Can dilute and give as a retention enema – Give iodine one hour after thionamides • Lithium – – – – Patient’s with iodine allergy 300 mg Q6 hrs Titrate to level of 1 mEq/L Renal and neurological toxicity impair lithium’s usefulness Thyroid Storm Management • Corticosteroids – Decrease secretion of thyroid hormone and decrease T4 to T3 conversion – Hydrocortisone 100 mg Q8 hrs – Dexamethasone 2 mg Q6 hrs – Use for 2 weeks Thyroid Storm Management • B-adrenergic blockade – Need higher doses – Propranolol 0.5 to 1.0 mg initially with monitoring up to 2-3 mg in 1 minutes • 60-80 mg oral every 4 hours – Esmolol loading 250-500 μg/kg • 50-100 μg/kg/minute – Can use diltiazem and guanethidine • Asthma and heart failure • With tachyarrhythmia can use loading propranolol Thyroid Storm Management • Hyperthermia – Cooling blankets – Acetaminophen – Avoid aspirin • Can displace thyroid hormones from binding proteins – Fluids 3-5 liters per day • Include glucose and thiamine – Depletion of liver glycogen and thiamine deficiency – Congestive heart failure • Diuretics • Digoxin – Requires higher doses in thyroid storm Thyroid Storm Management • Look for precipitating event – All febrile patients should be cultured – Unless source found, no empiric treatment needed • Once stable and T4 levels are decreasing can decrease dosing of thionamides Hyperthyroidism • Limit activity – In patients with heart disease • Increased risk of heart failure – Young patients • High output failure – Increased circulating volume – During exercise not able to increase LVEF • Not able to further decrease SVR Conclusion • Myxedema coma – Critical samples – Passive warming – Load Synthroid • Daily IV – Start Hydrocortisone – Look for inciting event • Thyroid storm – Critical samples – Control heart rate • B-blockade • Calcium channel blockade – Thionamide therapy – Look for inciting event