Thyrotoxic Crisis (Thyroid Storm): A Junior Doctor’s Guide

Introduction

Thyrotoxic crisis, or thyroid storm, is a rare but life-threatening complication of hyperthyroidism. It’s characterized by an extreme excess of thyroid hormones, leading to multi-system dysfunction. Without prompt recognition and management, thyroid storm can rapidly lead to severe outcomes such as heart failure, shock, or death. This post will guide junior doctors through the key aspects of history-taking, examination, investigations, and management, ensuring a thorough approach to this emergency.

History Taking in Thyrotoxic Crisis

A focused and structured history is crucial for recognizing thyroid storm. Key areas to cover include:

Key Questions to Ask:

·     Symptoms of Hyperthyroidism:

·     Ask about recent weight loss, despite normal or increased appetite.

·     Query about heat intolerance, excessive sweating, and palpitations.

·     Investigate any complaints of nervousness, anxiety, tremor, or insomnia.

·     Ask about menstrual irregularities in women.

·      Acute Symptoms Suggestive of Thyroid Storm:

·     Has the patient experienced fever, marked agitation, or confusion?

·     Are they reporting severe tachycardia or chest pain (which may suggest heart failure or arrhythmia)?

·     Are there signs of diarrhea or vomiting, which could indicate metabolic instability?

·     Precipitating Factors:

·     Ask about recent infections, as these can precipitate thyroid storm.

·     Have they undergone recent surgery or had significant trauma?

·     Explore the use of iodinated contrast agents, commonly used in imaging, or recent radioactive iodine treatment.

·      Non-adherence to antithyroid medications (such as carbimazole or methimazole) is a key trigger.

·      Personal and Family Medical History:

·     Establish a history of Graves' disease or other thyroid disorders.

·      Family history of autoimmune conditions can also be relevant.

Examination Findings in Thyrotoxic Crisis

In a thyrotoxic crisis, physical examination will yield critical information. Be methodical in evaluating the following:

·      General Appearance:

·     The patient may appear agitated or restless.

·     Look for signs of fever.

·     Vital Signs:

·     Fever (often > 38.5°C), tachycardia (> 140 bpm), and hypertension or hypotension (if shock is present) are common.

·      Assess for tachypnea or signs of respiratory distress.

·     Cardiovascular Examination:

·     Expect to find tachycardia, possibly progressing to atrial fibrillation.

·     Look for signs of heart failure: elevated JVP, peripheral edema, or pulmonary crackles on auscultation.

·     Neurological Examination:

·     The patient may be hyperreflexic, and fine tremors may be observed.

·     Signs of altered mental state: confusion, delirium, or even seizures may be present.

·     Dermatological Signs:

·     Check for warm, moist skin.

·     In Graves’ disease, there may be pretibial myxedema (localized skin thickening over the shins).

·     Thyroid eye disease: exophthalmos, lid lag, or ophthalmoplegia.

·     Abdominal Examination:

·      Look for hepatomegaly or tenderness, which can suggest liver dysfunction due to thyrotoxic hepatitis.

Investigations for Thyrotoxic Crisis

Investigations are key to confirming the diagnosis and guiding management.

·     Blood Tests:

·     Thyroid Function Tests (TFTs): Expect markedly elevated free T3/T4 with suppressed TSH.

·     Electrolytes and Renal Function: Hyponatremia, hypercalcemia, and raised creatinine can be present.

·     Liver Function Tests: May show elevated transaminases due to thyrotoxic hepatitis.

·     Glucose: Hyperglycemia can occur.

·     FBC (Full Blood Count): Look for evidence of infection (leukocytosis) or anemia.

·     CRP/ESR: Elevated if infection or inflammation is present.

·     ECG:

·     Expect sinus tachycardia or atrial fibrillation. If there are signs of heart failure, look for ischemic changes.

·     Chest X-ray:

·      Check for pulmonary edema if heart failure is suspected.

·     Imaging (if needed):

·     Thyroid ultrasound may show an enlarged gland, but is not typically required in the acute setting.

·      A CT brain may be considered if altered mental status suggests alternative causes like intracranial pathology.

Management of Thyrotoxic Crisis

Management of thyroid storm requires an urgent, multidisciplinary approach, focusing on reducing thyroid hormone production, controlling symptoms, and addressing precipitating factors.

·       Immediate Stabilization:

• Airway, Breathing, Circulation (ABCs): Ensure the patient is hemodynamically stable and give supplemental oxygen if hypoxic.

• Establish IV access and initiate IV fluid resuscitation with isotonic fluids (e.g., normal saline) to address dehydration and electrolyte imbalances.

·       Symptom Control:

• Beta-blockers (e.g., propranolol): Administer to control tachycardia, palpitations, and anxiety. Propranolol also reduces peripheral conversion of T4 to T3.

• Antipyretics (e.g., paracetamol): For fever control. Avoid NSAIDs, as they can displace thyroid hormones from binding proteins.

·       Reducing Thyroid Hormone Synthesis:

• Thionamides (e.g., propylthiouracil (PTU) or carbimazole): PTU is preferred in thyroid storm as it also inhibits peripheral conversion of T4 to T3. PTU 600 mg orally or via NG tube initially, followed by smaller maintenance doses.

• After an hour of thionamide, administer potassium iodide or Lugol’s iodine to inhibit further thyroid hormone release from the gland.

·       Steroids:

• Hydrocortisone 100 mg IV every 6–8 hours: Steroids help reduce thyroid hormone conversion and may treat potential adrenal insufficiency in severe illness.

·       Treat Precipitating Factors:

• Administer antibiotics if an infection is suspected.

• Address other triggers such as discontinuation of antithyroid drugs or recent surgery.

·       Supportive Care:

• Monitor vital signs closely and ensure continuous ECG monitoring for arrhythmias.

• Consider ICU admission for patients in shock or with multi-organ failure.

Thyrotoxic crisis is a true endocrine emergency that requires prompt recognition and aggressive management. Junior doctors should remain vigilant when assessing patients with a known history of hyperthyroidism or symptoms suggestive of thyroid storm. A systematic approach to history-taking, examination, investigations, and management will ensure the best outcomes for these critically ill patients.