What is Plasmin?

Mary McMahon
Mary McMahon

Plasmin is an enzyme produced in the body for the primary purpose of breaking down fibrin, a key component in blood clots. This enzyme acts as an anticoagulant and clot disperser inside the body. It is part of a large family of proteins and enzymes that respond to injuries in a cascading series of reactions that begins when an injury occurs and ends when the healing process is complete. Numerous labs manufacture these compounds for use in scientific research, including components from both human and animal sources.

Plasmin works to disperse blood clots.
Plasmin works to disperse blood clots.

The body needs a steady supply of plasmin to respond to ongoing needs, but having it activated and moving throughout the body can result in problems. It addresses this issue by making an inactive precursor known as plasminogen. Plasminogen is produced in the liver and it circulates freely. When a need for plasmin occurs, chemicals that cleave the plasminogen to activate it by turning it into plasmin are released.

Drinking plenty of water may help boost circulation and flush out toxins that could cause blood clots.
Drinking plenty of water may help boost circulation and flush out toxins that could cause blood clots.

This enzyme is known as a proteolytic enzyme because it breaks down proteins. In addition to breaking down fibrin, it can also act on fibrinogen, the precursor to fibrin, and several other proteins found in the body. Plasmin could be thought of as the enzyme that comes along for cleanup once a clot is no longer necessary. If clots were left in place, they would grow and could eventually break off, a very undesirable state of affairs. Plasmin dismantles the fibrin so that the clot can break up and be expelled from the body safely.

Once a clot is broken apart into its components, the body can expel unneeded parts as waste products and recycle the others for production of other proteins and enzymes. This process is continually occurring, generating a steady supply of materials to respond to new injuries and other needs. These processes are regulated by a number of genes that code for the production of specific proteins, enzymes, and other compounds in the body.

As a clot buster, plasmin has therapeutic applications. Patients who are not producing enough of the enzyme, or who have a clotting problem, can be given infusions of plasmin to break up their clots safely. Other anticoagulant medications can be used for this purpose, as well in patients with thickened blood, excessive clotting, and related medical issues. These medications need to be administered carefully because an excess can be dangerous. Too many anticoagulants may prevent a patient's blood from clotting when it needs to, leading to hemorrhage.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@fify-- You're basically right.

Hemorrage means excessive bleeding. So if someone who has too much plasmin has a cut or has surgery where an incision is made, there could be excessive bleeding because plasmin breaks up clotting at a faster rate than it should.

If it's exactly the opposite, where there is not enough plasmin, the blood will clot, but the clot won't dissolve afterward and will lead to thrombus or thrombosis (another world for blood clot).

So you can see from these examples that the amount of human plasmin is really important. It needs to be just right for coagulation (clotting) to happen correctly.

Something else that you might need to know is that plasmin is activated several days after a clot is formed. So if you cut your finger, it bleeds and clots; the clot will remain for a couple of days until it heals. When it has healed, the plasmin will get rid of the clot.


This is interesting. So if someone doesn't have enough plasmin, or has too much of it, what happens?

The article said that if there is too much plasmin, there would be hemorrage. What's hemorrage?

Is this like the disease where people can't stop bleeding when they have cuts and injuries because their blood doesn't clot?

But I guess the difference would be that in someone with a lot of plasmin, there would be clotting but the plasmin would break up the clot too quickly for the bleeding to stop.

Am I right? Can anyone explain more about plasmin activity in bleeding?


Having a clotting issue, on either end of the spectrum, would be frightening. My body's plasmin level has always been normal, and I've never had any problems forming clots and dissolving them.

I have an aunt who died of a blood clot, though. She had been taking a plasma inhibitor, and apparently it inhibited it too much.

The doctor had prescribed it to her because she seemed to exhibit all the symptoms of a mild hemophiliac. Maybe since hers was a mild case, she didn't really need such a strong medicine.


One of my friends has a moderate case of hemophilia. She lacks clotting factors, so she bleeds too much from small scrapes or punctures.

She has to take a plasmin inhibitor so that she doesn't bleed out. She also takes clotting factor replacement therapy to prevent bleeding.

Before she started her treatment, something as simple as getting a flu shot would cause her to bleed profusely. She often got random nosebleeds, and she would lose a scary amount of blood before they stopped.

It's scary to think that your own body could act against itself like this. When plasmin is allowed to run wild, it stirs up serious trouble.


@seag47 – My husband's doctor thought he had a lack of plasmin in his body, so he placed him on an anticoagulant. It turned out that even the lowest dose was too much for him.

His gums started to bleed whenever he brushed his teeth, even though he used a soft bristled brush. He started getting weird bruises on his body, and he didn't remember hurting himself.

The doctor had scheduled a follow-up appointment the next week, because this medicine can do serious damage if not caught in time. When my husband told him about the bleeding and bruising, he decided to take him off the drug.


My dad takes an anticoagulant to help him with his clotting problem. Though the drug won't get rid of the clots that are already there, it will keep them from getting bigger, and it will prevent the formation of new ones.

He had a scary amount of clotting in his body, so more plasmin was needed. However, he does have to be careful and follow his doctor's instructions precisely. If he takes too much of the anticoagulant, he could bleed excessively.

The doctor told him to call him right away if he noticed blood in his urine or got any nosebleeds. These would mean that he had too much plasmin in his system, and he should stop taking the medicine until the doctor could adjust his dosage.

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