Case Of the Month 3 – Answer

 This case is a beautiful example of an important concept we need to remember.  When this patient hits the door, it screams sepsis and appropriately so.  But after initial workup, we do not find an obvious source of infection.  I think we all can agree that this patient will require an LP to r/o meningitis vs. encephalitis and we would all likely load him with broad-spectrum antibiotics +/- antivirals for suspected sepsis, but what if the CSF is negative and we never find a source?  This is the moment when we must think of alternative causes for SIRS aside from sepsis.  As a quick review, remember that SIRS criteria include a temperature > 100.4F or < 96.8F, RR > 20 or PaCO2 < 32, HR > 90, and WBC >12,000 or WBC < 4,000 or bands >10%.  2 of these nets you a diagnosis of SIRS and if a source of infection is found, you reach sepsis status.  The following Venn Diagram is a nice visual of this concept:

 

This patient clearly meets SIRS criteria (temp and HR) but barring infection in the CSF we would be admitting him with a diagnosis of SIRS.  At this moment, we need to start thinking of non-infectious causes of SIRS, especially the ones we can diagnose in the ED.  A very small list of non-infectious causes of SIRS that could be present in this patient include:

• Adrenal insufficiency
• Autoimmune disorders
• Dehydration
• Drug reaction
• Malignancy/Paraneoplastic syndrome
• Medication side effect
• Myocardial infarction
• Pancreatitis
• Seizures (partial and/or complex)
• Substance abuse
• Thyroid disease
• Toxic ingestion
• TTP-HUS
• Vasculitis

There are so many diagnoses which could fit this patient’s picture but any patient with fever, tachycardia and AMS should prompt a brief consideration for thyroid storm.  This patient does not have a history of thyroid dysfunction, but in patients with a precipitating event (such as a viral illness or any other infection), thyroid dysfunction can still occur.  Thyroid storm is diagnosed purely on clinical and physical grounds with lab studies being more or less confirmatory tests.  The most commonly used scale to stratify suspected thyroid storm is the Burch-Wartofsky score seen below:

A score over 25 makes thyrotoxicosis possible and greater than 45 probable.  Our patient gets 10 points for his temperature, 20 points for his mental status, 20 points his HR, and possibly 10 points for precipitant history if you highly suspect his viral URI two months ago as the catalyst.  His temperature was also not indicated as oral vs. rectal, and if his 100.8 was orally then a rectal temp might come back even higher, prompting a higher score.  Either way, he gets at least 50 points and thyroid storm should be considered.  Note how there are still many other diagnoses which could cause this patient to get a high Burch-Wartofsky score.  The point of this scoring system is not to make a diagnosis, but rather to guide your clinical judgement on whether or not it could be present.  By calculating a score for this patient, it could prompt us to send thyroid function studies from the ED and possible diagnose this critical illness. Think of the flip-side: if we don’t consider this non-infectious causes of SIRS, we could be admitting patients with thyroid storm to the floor for antibiotic therapy for “suspected sepsis”, potentially anchoring this diagnosis and delaying the diagnosis until there is clinical deterioration.  

This is an ICU-level pathology with high mortality if not treated promptly and requires close monitoring and titration of medications.  Treatment should not be delayed until TFT results return if thyroid storm is highly suspected.  In general, patients with hyperpyrexia should be cooled (possibly not needed in this patient), electrolyte abnormalities should be corrected (slowly and carefully in the case of hypernatremia) and IVF with dextrose should be considered (thyroid storm produces a high metabolic demand and patients can quickly deplete their glycogen stores). Specific therapy includes beta-blockade to minimize adrenergic symptoms and thionamides to correct the hyperthyroidism.  Propranolol can be used IV at a dose of 1mg (infused over 10 minutes) followed by 1-2mg given every few hours and titrated based on vital signs.  An esmolol drip at a rate of 50-100 mcg/kg/min allows for quicker titration.  PTU (200mg q4hrs) is preferred over methimazole (20mg q4-q6hrs) in severe thyroid storm as it has a quicker onset of action and prevents conversion of T4 to T3.  At least 1 hour after initiation of thionamide therapy, iodine compounds such as potassium iodine drops should be given orally or via NG tube to block the release of further thyroid hormone. Lastly, glucocorticoids can be given to reduce peripheral conversion of T4 to T3 and possibly mitigate relative adrenal insufficiency caused by hyperthyroidism.

• Any patient with SIRS who does not produce a source of infection after initial workup may have a non-infectious cause for their symptoms and those processes should at least be considered
• Fever and AMS are regularly implicated in thyroid storm and a patient with these symptoms should prompt a consideration to send thyroid levels
• Thyroid storm is a can’t-miss potentially fatal illness which can be diagnosed clinically in the ED, but due to symptom overlap with other illnesses you can only diagnose it if you are thinking about it!