Thyroid Storm/Thyrotoxic Crisis

What is a Thyroid Storm?

A thyroid storm is a complication of an overactive thyroid resulting in a hypermetabolic state and organ failure if not treated immediately.

Just as for other thyroid disorders, thyroid storm is more common in females.

What are the Causes of a Thyroid Storm?

A thyroid storm occurs in a patient who has already been suffering from hyperthyroidism with high levels of thyroid hormone. The levels of free thyroid hormone are increased in a thyroid storm. The levels of chemicals like adrenaline are increased in the body. Conditions that can precipitate a thyrotoxic crisis include the following:

• Surgery on the thyroid gland where handling of the gland releases excess hormones into the blood. Direct trauma to the neck region can cause a similar effect
• Intake of iodine or radioactive iodine used for the treatment of hyperthyroidism. External beam radiation for a thyroid nodule can also cause a thyroid storm
• Sudden stopping of anti-thyroid medications for hyperthyroidism
• Stressful conditions like emotional stress, systemic infections and diabetic ketoacidosis
• Pregnancy, delivery and the immediate postpartum period
• Other conditions like stroke and pulmonary thromboembolism
• Use of medications like the tyrosine-kinase inhibitor sorafenib for the treatment of cancer

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What are the Symptoms of a Thyroid Storm?

Symptoms and signs of a thyroid storm include the following:

• Abnormalities in heart rhythms and high blood pressure
• Dysfunction of the nervous system with symptoms including mild agitation, behavioral changes and even coma
• Problems with the digestive tract and the liver with symptoms including nausea, vomiting, diarrhea, abdominal pain, and jaundice
• Other signs of hyperthyroidism like increased appetite, loss of weight, and eye changes

Complications of a thyroid storm include the following:

• Failure of multiple organs
• Heart-related complications like congestive heart failure or arrhythmia
• Respiratory failure
• Disseminated intravascular coagulation due to abnormalities in the levels of clotting factors. The patient develops clots within the blood vessels
• Perforation of the digestive tract
• Sepsis or blood infection
• High body temperature / fever

How do you Diagnose a Thyroid Storm?

Diagnosis of a thyroid storm is based on the following:

• A medical history is obtained from the patient, who may have been diagnosed as suffering from thyroid disease in the past and gives the history of a precipitating event.
• The symptoms and signs may be obvious on physical examination.
• Blood tests which may indicate the following:
• High levels of the thyroid hormones, free T3 and T4, with undetectable TSH (thyroid stimulating hormone) levels

• The presence of anti-TSH antibodies and altered thyroglobulin levels may indicate the cause of the thyroid abnormality
• Other changes that may be noted may include the following:
• High bilirubin and transaminase levels
• High blood sugar levels
• Low cholesterol levels
• Electrolyte abnormalities like low potassium levels
• Abnormalities in clotting factors like deficiency of antithrombin or high levels of factor VIII
• An ultrasound or a thyroid scan will reveal the underlying thyroid disease.
• An electrocardiogram (ECG)can assess the heart function.
• A chest x-ray may reveal heart enlargement, or fluid accumulation or infection in the lungs

Scores have been used to arrive at the diagnosis of a thyroid storm based on the symptoms, signs and diagnostic tests.

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How do you Treat a Thyroid Storm?

A thyroid storm is a medical emergency and requires immediate hospitalization.

• Oxygen support and mechanical ventilation are administered if necessary
• Fluids and electrolytes are administered to correct the imbalances. Fluids should be restricted in patients with heart failure
• Cooling mattresses are used to reduce fever
• Medications that are used include:
• Acetaminophen to reduce fever. Aspirin should be avoided
• Beta blockers like propranolol to prevent the deleterious effect of hormones on the heart and the conversion of the thyroid hormone to its active form
• Antithyroid medications like propylthiouracil and methimazole to reduce the thyroid hormone levels. L-carnitine has been shown to have additive effects with methimazole. It should be remembered that propylthiouracil can cause liver failure and should be used as an alternative only when other treatments cannot be used
• Large doses of iodine which inhibit the release of thyroid hormone from the thyroid gland. Lithium carbonate may be used as an alternative.
• Hydrocortisone which is administered intravenously
• Phenobarbitone to sedate the patient and reduce thyroid hormone levels
• Diuretics, ACE inhibitors and beta blockers along with other measures to treat heart failure
• Heparin in patients with atrial fibrillation to prevent spread of clots from the heart to other parts of the body. The abnormal heart rhythm should also be appropriately treated
• Antibiotics to treat infections

• Extracorporeal plasmapheresis may be used, which is a process which filters off excess free thyroid hormone from the blood
• Surgery to remove the thyroid gland may be performed in some cases after the patient has been stabilized

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Health Tips

• Patients with hyperthyroidism should take treatment on a regular basis to control their thyroid hormone levels

• Drugs belonging to beta blockers should be administered to patients undergoing radioactive iodine treatment for hyperthyroidism