In Pathology, What Is a Pyrogen?

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  • Written By: Mary McMahon
  • Edited By: A. Joseph
  • Last Modified Date: 19 October 2019
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A pyrogen is a protein that can induce a fever in a patient by triggering a series of immune reactions. Some are endogenous, developing within the body, and others are exogenous and might be introduced through contaminated food or medication. Exposure to pyrogens can cause severe fever and might endanger a patient if the temperature is consistently high or accompanied by complications such as a hemorrhage. A number of steps need to be taken to produce products without such compounds and to test finished products to identify contaminants that might pose a health risk.

In the body, a pyrogen acts like a cytokine, a signaler in the immune system. This leads the immune system to react, causing a temperature spike. If the fever gets high enough, the patient might develop an altered level of consciousness and could fall into a coma. Severe fevers might cause permanent neurological damage along with other health problems and can be fatal in some cases. If a patient was already ill before the pyrogen exposure, it can downgrade the patient's prognosis or long-term outlook.

One potential source of these compounds is contaminated medications. Numerous bacteria produce pyrogens, usually as part of their cell walls. If they get into batches of medication, they can cause disease in patients. Especially when a medication is directly injected, the patient's body might be hit by a blast of pyrogens, and the patient could experience a severe injection reaction, sometimes within minutes.


Even sterile solutions can be contaminated if they are not handled properly during production. Rigorous filtration is necessary at every step to keep the contents pure, and they must be handled with care until they are sealed in packaging for shipment. Drug companies use periodic pyrogen testing to check on the safety of their products. If a batch contains pyrogens, the company can destroy it or recall it, depending on whether the medication has reached the market.

Direct infections also can cause pyrogen release in the body. Some bacterial infections are associated with fevers and other extreme reactions caused by bacterial toxins. Bacteria might produce toxins as a byproduct of other activities or when they die. Paradoxically, antibiotic therapy sometimes can make a patient temporarily sicker by killing off the bacteria and triggering a mass release of toxins. If an infection involves bacteria that are known to cause this, the doctor might exercise caution when prescribing, to limit risks to the patient.


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Post 2

@miriam98 - If you buy a vial from the pharmacy they will advertise that it has a drop of pyrogen free water.

I don’t understand the chemical process involved, but it’s clear that you can’t inject yourself with regular tap water or even filtered water, assuming you were going to inject yourself with any medication at all.

Post 1

Now you know why all that medical equipment in the doctor’s office is sterilized. Medical equipment can also introduce pyrogens into the bloodstream, from what I understand.

Medical equipment manufacturers have to demonstrate that their equipment is pyrogen free. I believe that the FDA governs medical equipment as well as drugs.

I am not an expert but a friend of mine works for a company in our town that sells dental supplies, and this is what he tells me.

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