Diagnosis

Thyrotoxicosis

Etiology

Cause a trigger + an underlying thyroid condition [ymi][tdh][84y]

• Therapeutic:

  • Inadequate antithyroid drugs

  • Excess iodine in patients with hyperthyroidism

  • Excess thyroid hormone ingestion

  • Iodide (amiodarone) --> iodine induced hyperthyroidism

  • Recent radioablation

• Autoimmune: release of preformed thyroid hormone

  • Graves’ disease

  • Hashimoto’s thyroiditis

  • Subacute thyroiditis (De Quervan’s)

  • Postpartum thyroiditis

  • Reidel thyroiditis

• Tumor:

  • Autonomously functioning thyroid nodules (iodine deficiency)

  • Toxic multinodular goitre

  • Thyroid adenoma

  • TSH-secreting pituitary adenoma

  • Metastatic thyroid cancer

  • Struma ovarii (ovarian teratoma producing thyroid hormone)

  • hCG-secreting hydatidiform mole

• Surgery:

  • Thyroidectomy

  • Nonthyroid surgery (incomplete beta-blockade and noneuthyroid patients)

• Infection

• Diabetic ketoacidosis

• Transient neonatal hyperthyroidism

• Drugs can cause thyrotoxicosis

• TSH receptor mutations

• McCune Albright syndrome

Pathophysiology [ymi]

1. Anterior pituitary gland produce TSH --> stimulates the thyroid gland

2. The thyroid gland regulates metabolism by producing and releasing T3 and T4

   • Increased basal metabolic rate

   • Enhanced tissue thermogenesis (upregulation of β-adrenergic receptors, which in turn increases sympathetic activity)

   • Increased heart rate and myocardial contractility (inotropy and chronotropy)

   • Decreased systemic vascular resistance --> activated renin-angiotensin system --> sodium reabsorption and blood volume expansion --> increased preload --> ventricular hypertrophy --> congestive heart failure

   • Increased oxygen consumption

3. Clinical presentation varies: Asymptomatic state --> Thyroid storm (life-threatening)

   • Tachycardia

   • Weight loss

   • Heat intolerance

   • Palpitations

   • Tremor

   • Anxiety

   • Delirium

Complications [ymi]

• Delirium

• Altered mental status

• Osteoporosis

• Atrial fibrillation

• Heart failure

• Thromboembolic disease

• Seizure

• Cardiovascular collapse

• Death

Epidemiology

Incidence per 100.000 [yhs][kw2][hbv][a1f][st4][shy][w2q][3zo][fzf]

Approach

• Blood test: T3 and T4 levels, TSH antibody testing

• Radioactive iodide uptake

Diagnostic classification:

• Burch and Wartofsky [2fz][tdh]

  1. Fever

  2. Tachycardia

  3. Congestive heart failure

  4. Gastrointestinal-hepatic dysfunction: diarrhea, abdominal pain,

     nausea/vomiting, jaundice

  5. Central nervous system disturbance: agitation, delirium, psychosis,

     extreme lethargy, seizure, coma

• Japan Thyroid Association [84y][tdh]

  1. Elevated free triiodothyroine [T3] and/or thyroxine [T4] levels

  2. CNS manifestations: restlessness, delirium, mental aberration/psychosis, somnolence/lethargy, convulsion, or coma

  3. Fever (38°C or higher)

  4. Tachycardia (130 beats/min or faster)

  5. Congestive heart failure

  6. Gastrointestinal (nausea, vomiting, diarrhea, or jaundice) and hepatic manifestations

Treatment

1. Identify the underlying condition [ymi]

2. Treatment of systemic symptoms: high fever, dehydration, shock, and DIC

   • β-blockers

   • Antipyretics

   • IV fluid

   • Anticoagulation

3. Organ-specific manifestations (cardiovascular, neurological, and GI)

4. Definitive treatment of thyrotoxicosis: [tdh]

   • Antithyroid drugs

   • Thyroidectomy

   • Radioactive iodine treatment

Differential diagnoses

Amphetamine toxicity, Atrial fibrillation, Cocaine toxicity, Cushing syndrome, Diabetes mellitus, Drug side effects, Graves disease, Heart failure, Hypoglycemia, Pheochromocytoma, Psychotropic drugs, Struma ovarii, Subacute thyroiditis, Thyroid cancer, Toxic nodular goiter, Toxic thyroid adenoma