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Approach to the Diagnosis of Hyperthyroidism - Differential Diagnosis and Workup Algorithm • Secondary Hyperthyroidism (↑↔TSH, ↑Total T3/Free T4) • Subclinical Hyperthyroidism (↓TSH, ↔Total T3/Free T4) • Overt Hyperthyroidism (↓TSH, ↑Total T3/Free T4) • ß-hCG-associated Hyperthyroidism (↑↑↑ ß-hCG) • Hyperthyroidism unlikely (↔TSH, ↔Total T3/Free T4) Radioactive Iodine Scan - High Uptake: • Graves disease • Low iodine state, Gestational trophoblastic disease • Toxic adenoma, Multinodular goiter Radioactive Iodine Scan - Low Uptake: • Early Hashimoto thyroiditis (i.e., hashitoxicosis) • Thyroiditis, Iodine (e.g. contrast), Struma ovarii, Amiodarone • Exogenous thyroid hormone use Matthew Ho, MD PhD @MatthewHoMD #Hyperthyroidism #Differential #Diagnosis #Algorithm #endocrinology

$Approach to Thyroid Function Tests in the Evaluation of Hyperthyroidism • Low TSH, Low normal T4$

Approach to Thyroid Function Tests in the Evaluation of Hyperthyroidism • Low TSH, Low normal T4 → Possibly Central Hypothyroidism. unlikely subclinical hyperthyroidism. • Low TSH, normal T4 +/- T3 → Subclinical Hyperthyroidism: Work-up similar to hyperthyroidism as below. Can repeat labs 6 weeks after the resolution of pregnancy, critical illness, and dopamine agonists/octreotide. • Low TSH, high T4 +/- T3 → Primary Hyperthyroidism → Signs of symmetrically enlarged thyroid & ophthalmopathy → Graves' Disease → Confirm with TRAb → Radioactive Iodine Uptake & Scan • High or normal TSH, high T4 +/- T3 → Central (secondary) Hyperthyroidism → MRI Pituitary - Dr. Claire Brickson @crbricks #Hyperthyroidism #algorithm #diagnosis #endocrinology #TFTs #TSH #Interpretation

Graves Hyperthyroidism - Diagnosis and Management Algorithm Low TSH -> TSH-R-Ab+ -> Graves' Hyperthyroidism doi: 10.1210/clinem/dgaa646 #Graves #Disease #Hyperthyroidism #Management #Algorithm #treatment #diagnosis #endocrinology

Abnormal Serum TSH - Differential Diagnosis Algorithm Increased TSH • Hypothyroidism • Sub-clinical Hypothyroidism • Recovery from Non-Thyroid Illness Decreased TSH • Hypopituitarism • Thyrotoxicosis • Non-Thyroid Illness • Sub-Clinical Thyrotoxicosis • T3 Toxicosis #TSH #Differential #Diagnosis #Algorithm #Hypothyroid #Hyperthyroid #Endocrinology

Thyroid Function Test Interpretation Table TSH, Free T4, Free T3 and Associated Condition #Diagnosis #Endocrinology #Hyperthyroid #Hypothyroid #Function #Tests #TFTs #Comparison #Table #TSH #FreeT3 #FreeT4 #Labs #Interpretation

Hyperthyroidism Overview Clinical Manifestation of Hyperthyroidism: • Fatigue • Weight loss • Heat intolerance • Depression, nervousness • Irritability, anxiety or agitation • Menstrual irregularities • Weakness or tremors • Palpitations • Exertional dyspnea • Hyperdefecation • Anterior neck pain • Insomnia Primary Hyperthyroidism: • Toxic multinodular goiter (Hot nodule) • Toxic uninodular goiter • Toxic diffuse goiter (Graves' disease) • Thyrotoxicosis associated with thyroiditis Secondary Hyperthyroidism: • Factitious thyrotoxicosis • T3 Toxicosis • Iodine loads • Metastatic Follicular CA • Malignancies with circulating thyroid stimulators • TSH-producing pituitary tumors • Struma Ovarii with hyperthyroidism Diagnosis: • ↓ Low TSH • ↑ Total T3 • ↑ Free T4 • Thyroid stimulating immunoglobulin (TSI) or Thyrotropin (TSH) receptor antibodies (TRAb) if Graves' disease is suspected • Thyroid scintigraphy with radioactive iodine uptake • Thyroid US: Vascularity, Nodules, Size Thyroid Storm: • Life threatening: - Tachycardia. Cardiac arrhythmia - Fever (Hyperpyrexia) - Perspiration - Diarrhea - Anxiety, agitation, psychosis - CHF - Hypotension • Labs: - ↓ TSH, ↑ FT4 and/or ↑ T3 - Mild hypercalcemia, Hyperglycemia - ↑ AST/ALT • Treatment: - Beta blocker - Thionamide - Iodine solution - Iodinated radiocontrast agent - Glucocorticoids: Reduce T4 -> T3 - Bile acid sequestrants Hyperthyroidism Physical Examination: • Moist palms • Thickening of skin: pretibial • Bulging eyes (lid retraction or proptosis), unblinking stare • Tremor • Eye irritation, peri orbital edema, diplopia, change in visual acuity • Hyperreflexia • Tachycardia • Tachypnea • Goiter (+/- bruit) • Thyroid thrill • Ophthalmoplegia • Atrial fibrillation/flutter • Abdominal tenderness Treatment: • Beta blockers • Thioamides (Methimazole and PTU) • Radioactive iodine therapy • Thyroidectomy #hyperthyroidism #causes #diagnosis #differential #endocrinology #signs #symptoms #thyroid

Hyperthyroidism and Thyrotoxicosis Interpretation Table - Autonomy (Graves) - Autonomy (toxic nodule) - Exogenous thyroid hormone - Release of preformed hormone MGH IM Residents @mghmedres #Hyperthyroidism #Thyrotoxicosis #Interpretation #Table #diagnosis #endocrinology #graves

Hyperthyroid States - Comparison Table - Laboratory Findings via RebelEM @srrezaie #Diagnosis #Endocrinology #Hyperthyroid #States #Comparison #Table #TSH #FreeT3 #FreeT4 #Labs #Laboratory #Findings #Interpretation #TFTs #Tests #RebelEM

Types of Anion Gap Acidosis - AGAPS KIL U - Mnemonic Ketoacidosis: Alcoholic Ketoacidosis, Starvation Ketoacidosis, Starvation Ketoacidosis Ingestions: Alcohols (Ethylene Glycol, Ethanol, Methanol), Salicylates, Acetaminophen, Iron, INH Lactic Acidosis: • L-Lactic Acidosis - From Anaerobic metabolism, Tumors, or Medication induced • D-Lactic Acidosis - From Short Gut or IV Lorazepam Uremia: • Failure to secrete Hydrogen and excrete Ammonia • Accumulation of Phosphate and other organic acids Unremarkable Labs @UnremarkableLab #AnionGap #Acidosis #AGAPSKILU #mnemonic #differential #diagnosis #causes

Metabolic and Respiratory Acidosis and Alkalosis - Diagnostic Algorithm Anion gap - MUDPILES: - Methanol (formic acid) - Uremia - Diabetic ketoacidosis - Propylene glycol - Iron tablets or INH - Lactic acidosis - Ethylene glycol (-> oxalic acid) - Salicylates (late) Normal anion gap - HARDASS: - Hyperalimentation - Addison disease - Renal tubular acidosis - Diarrhea - Acetazolamide - Spironolactone - Saline infusion #Diagnosis #Acidosis #Alkalosis #Respiratory #Metabolic #Algorithm #MUDPILES #HARDASS ** GrepMed Recommended Text: Nephrology Secrets - https://amzn.to/2Z74DhY