Thyroid storm
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For patient information, click Thyroid storm
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: Thyrotoxic storm, accelerated hyperthyroidism, hyperthyroid storm
Overview
An unusual but life threatening condition develops in patients with hyperthyroidism either due to poorly controlled pre existing hyperthyroidism or due to medical conditions that precipitate a crisis situation called thyroid storm. There develops a hypermetabolic state that leads to its development. It is mainly a clinical diagnosis and warrants prompt treatment.
Historical Perspective
Classification
Pathophysiology
Thyroid storm is a state of decompensation of the hyperthyroid gland. It could be either due to increased levels of thyroid hormones, increased responsiveness to catecholamines, enhanced response to thyroid hormones at the cellular level, presence of unique catecholamine like substance in hyperthyroidism or due to direct sympathomimetic effect of thyroid hormone due to its structural similarity to catecholamines . The exact cause is not clear. Also, it has been found that it is only the free T4 and T3 that are high. The levels of total T4 and T3 are fairly similar to those found in hyperthyroidism. For a hyperthyroid patient just being intolerant to heat and exhibiting diaphoresis, thyroid storm makes one hyperpyrexic. The enhanced metabolism is translated into increased oxygen and energy consumption. Similarly, moderate tachycardia of hyperthyroidism enhances to hypertension , arrhythmias and possibly high output heart failure. Irritable and restless patient of hyperthyroidism now has agitation, delirium, seizures and could progress to coma. The exact cause behind this heightened effect is unclear.
Genetics
Associated Conditions
Gross Pathology
Microscopic Pathology
Causes
Common Causes
Causes by Organ System
| Cardiovascular | Medical stressors like myocardial infarction. |
| Chemical / poisoning | No underlying causes |
| Dermatologic | No underlying causes |
| Drug Side Effect | Iopromide, Pseudoephedrine, Salicylates, NSAID, Chemotherapy, excessive thyroid hormone ingestion, Withdrawal or non compliance with antithyroid medication, acute iodine load. Iodixanol |
| Ear Nose Throat | No underlying causes |
| Endocrine | TSH secreting tumour, Hyperfunctioning thyroid nodule, Hyperfunctioning multinodular goiter, diabetic ketoacidosis. |
| Environmental | No underlying causes |
| Gastroenterologic | No underlying causes |
| Genetic | McCune Albright syndrome |
| Hematologic | No underlying causes |
| Iatrogenic | No underlying causes |
| Infectious Disease | Recent infection. |
| Musculoskeletal / Ortho | No underlying causes |
| Neurologic | No underlying causes |
| Nutritional / Metabolic | No underlying causes |
| Obstetric/Gynecologic | Transplacental passage of maternal thyroid hormone immunoglobulins in neonates, toxemia of pregnancy, molar pregnancy, parturition. |
| Oncologic | No underlying causes |
| Opthalmologic | No underlying causes |
| Overdose / Toxicity | No underlying causes |
| Psychiatric | No underlying causes |
| Pulmonary | No underlying causes |
| Renal / Electrolyte | No underlying causes |
| Rheum / Immune / Allergy | No underlying causes |
| Sexual | No underlying causes |
| Trauma | Direct trauma to the gland. |
| Urologic | No underlying causes |
| Dental | No underlying causes |
| Miscellaneous | Anaesthesia induction, vigorous palpation of thyroid gland, any surgery. |
Causes in Alphabetical Order
Make sure that each diagnosis is linked to a page.
Differentiating thyroid storm from other Diseases
Epidemiology and Demographics
The frequency of thyroid storm is unknown in children. In a national survey in Japan, incidence of thyroid storm in hospitalized patient was found to be 0.20 per 100,000 per year. If the diagnosis is promptly made and early management initiated, the adult mortality rate is less than 20% contrary to a rate of 90% if patient left untreated.
Age
Children aged 10-15 years account for greater than 2/3rd cases of thyrotoxicosis. Hence, thyroid storm is more common in adolescents though it can occur in any age group.
Gender
Hyperthyroidism is 3-5 times more common in females than males. Incidence of thyroid storm is presumed to be higher in females but no clear data is available.
Race
Developed Countries
Developing Countries
Risk Factors
Screening
Natural History, Complications and Prognosis
Congestive heart failure and pulmonary edema can develop rapidly and lead to death.
Diagnosis
History
The patient may be a known case of hyperthyroidism or may present initially with severe symptoms of thyroid storm.
Symptoms
Hyperpyrexia ie. temperature > 104'F, tachycardia > 140/min or Atrial fibrillation and delirium or agitation are typical features of thyroid storm. Other features include -
- General- profuse sweating, poor feeding, weight loss, respiratory distress, fatigue.
- Cardiovascular- pulmonary edema, hypotension, arrhythmia and death from cardiovascular collapse.
- Gastrointestinal- severe nausea, vomiting, diarrhea, abdominal pain, hepatic failure, unexplained jaundice.
- CNS- agitation, anxiety, delirium, psychosis, stupor, seizures and coma.
Burch and Wartofsky introduced a scoring system for identification of thyroid storm. They used criteria like thermoregulatory dysfunction, cardiovascular dysfunction, central nervous system effects, heart failure, gastro-intestinal-hepatic dysfunction and precipitant history. A score >45 is highly suggestive of thyroid storm while score <25 makes it unlikely. A score of 25-44 is suggestive of an impending storm.
Past Medical History
Family History
Social History
Occupational
Alcohol
The frequency and amount of alcohol consumption should be characterized.
Drug Use
Smoking
Allergies
Physical Examination
Appearance of the Patient
The patient has features of hyperthyroidism like profuse sweating and orbital signs like lid lag etc. The patient would be in a state of agitation or confusion or maybe seizing or could present with coma.
Vital Signs
Thyroid storm is characterized by high fever (>38.5'C or 101.3'F). This may progress to hyperpyrexia (>40'C or 104'F). There could be hypotension or hypertension with a wide pulse pressure. The tachycardia in thyroid storm is out of proportion to the fever. The patient may have heart rate upto 140/min and may progress to atrial fibrillation.
Skin
There will be typical features of hyperthyroidism like warm and moist skin.
Head
Eyes
The eye signs are similar to those found in hyperthyroidism like exophthalmos, lid retraction, lid lag, wide palpebral fissure, staring expression, inability to keep eyeballs converged.
Ear
Nose
Throat
A palpable goiter may be felt in the neck.
Heart
There would be signs of right sided heart failure like edema, hepatomegaly, ascites, rales, etc. Thyroid storm is associated with supraventricular tachycardia , though ventricular tachycardia can also occur.
Lungs
Abdomen
Extremities
Neurologic
The patient would be in altered mental status ranging from agitation, confusion, seizures, stupor and coma. There could be tremors and some pyramidal signs.
Genitals
Other
Laboratory Findings
The diagnosis of thyroid storm is mainly clinical and if suspected, immediate treatment should begin without waiting for laboratory results. The laboratory findings are similar to hyperthyroidism and are as follows-
- Thyroid function test- elevated free T3 and T4 and may or may not have decreased TSH. There is increased T3 resin uptake and elevated 24 hr iodine uptake.
- Complete blood count- mild leukocytosis with shift to left.
- Liver function test- non specific abnormalities like increase in alanine transaminase(ALT), aspartate transaminase(AST), lactate dehydrogenase(LDH), alkaline phosphatase(ALP) , Creatine Kinase and serum bilirubin.
Electrolyte and Biomarker Studies
Electrocardiogram
One could find narrow complex QRS suggestive of supraventricular tachycardia or 3 or more ventricular beats at a rate of 110-250/minute suggestive of ventricular tachycardia. Of the supraventricular tachycardia, atrial fibrillation is the most common one characterized by absent P waves, unorganized electrical activity in their place and irregular R-R interval.
Chest X Ray
Features of cardiomegaly may be found which are suggestive of congestive heart failure. There could also be features of pulmonary edema like increased fluid in alveolar walls, Kerley B lines , increased vascularity in the peri hilum region (classical bat wing appearance) suggestive of pulmonary edema.
CT
In view of features like agitation, confusion, delirium etc, a CT scan of head may be needed to rule out intracranial causes.
MRI
Echocardiography or Ultrasound
Other Imaging Findings
Other Diagnostic Studies
Treatment
Pharmacotherapy
The main aims of medical therapy are as follows-
- Reduce effects of thyroid hormone on peripheral tissues.
- Decrease further synthesis of thyroid hormone
- Decrease release of hormone
- Prevent further TH secretion and peripheral conversion of T4 to T3.
The medications used to accomplish the above aims are described as follows (in order of the aims)-
- 1) Beta-blockers
Beta blockers block peripheral conversion of T4 to T3. Exercise caution while using in patients with congestive heart failure and cardiomyopathy. They are known to precipitate cardiac arrest in patients with cardiomyopathy.
- Propanolol- nonselective beta adrenergic antagonist, used widely.
- Esmolol- beta 1 specific antagonist with a short duration of action.
- 2) Antithyroids
Propylthiouracil is the drug of choice for thyroid storm that prevents organification, trapping of iodide to iodine and also peripheral conversion of T4 to T3. It is available only as per oral medication and hence comatosed patients may need to be given via nasogastric tube. It causes more rapid decrease in T3 levels than methimazole.
Methimazole has similar mechanism of action as propylthiouracil except it does not inhibit peripheral conversion. It is more potent than propylthiouracil. It is also only available as per oral formulation. It has longer duration of action, used in non life threatening situations. It is less hepatotoxic therefore all patients started on propylthiouracil should be started on methimazole before discharge.
Few patients may be one unable to take antithyroids due to side effects like agranulocytosis, hepatotoxicity and/or allergy. Thyroid storm has been found to develop in patients upon discontinuation of antithyroids. In that case, on should go for a week course of steroid, Lugols iodine, beta blockers and proceed with thyroidectomy on the 8th day.
- 3) Iodides
Lugol solution has 100 mg potassium iodide and 50 mg iodine. It also inhibits peripheral conversion of T4 to T3 within hours. It has to be given in thyroid storm but atleast 1 hour after antithyroid administration. This is done so that there is no chance that iodine be used to make new thyroid hormones. By giving antithyroids first all synthesis steps will be blocked and iodine then would be an added bonus in blocking release of already formed hormones. Side effects of iodine are direct injury to esophagus.
- 4) Glucocorticoids and iodine contrast agents
The 4th aim is fulfilled by both glucocorticoids and iodine contrast agents.
- Steroids have been found to be associated with improved survival. They also effect the autoimmune process in case of crisis due to Graves disease. Preferred steroid is hydrocortisone.
- Iodinated contrast agents are presently not available in the US due to doubts on their efficacy. As was with iodine, these are also given an hour after antithyroids.
- Other therapies
- Lithium- given to block release of thyroid hormone but its toxic to liver.
- Plasmaphereis- has been tried when other therapies failed.