MadSci Network: Anatomy

Re: What is the effect of a Steroid injection in soft tissue?

Area: Anatomy
Posted By: Tom Wilson, M.D./PhD, Pathology, Div. of Molecular Oncology, Washington University School of Medicine
Date: Thu Jul 3 00:52:45 1997
Area of science: Anatomy
ID: 865873299.An
First, I would like to apologize for the delay in answering this question.  
It slipped through the cracks of my email network during some computer down 
time.  We try not to have these things happen, but sometimes........

With that said, I am not sure that I understand your question.  First, let 
me be clear that "steroid" is a general term applied to a large class of 
hormones made by your body .  The different subclasses of steroids are 
related by their chemical structure, but their actions are quite different.

I imagine that you are referring to the common medical practice of 
injecting the subclass of steroids called "corticosteroids" (e.g. 
hydrocortisone) into joints and other body parts to relieve pain, etc.  
Corticosteroids (normally made by the adrenal gland) have many effects in 
the body.  One of them is to limit the function of the immune system, which 
is why they are called "anti-inflammatory", i.e. that they limit 
inflammation.  Inflammation is a difficult concept to define, but you can 
think of it as the concerted action of the immune system at a tissue level.  
When different immune system cells come into an area of the body they 
create a characteristic set of changes that are important to processes like 
fighting infections.  The four outwardly apparent hallmarks of these 
changes - pain, swelling, redness and heat - are largely due to the 
increased leakiness of blood vessels.  Unfortunately, these same changes 
can also be damaging to the tissues, especially when they are happening out 
of control as in many disease states.

So, injection of corticosteroids into tissues is done to limit the 
inflammatory response that is occurring at that local site, i.e. to limit 
the activation of the immune cells.  In this way, high local concentrations 
of steroids can be achieved without having to expose the entire body to 
potentially harmful amounts of steroids.  Note that the other main way to 
limit inflammation is to use drugs (e.g. Advil, etc) known as NSAIDs, which 
stands for non-steroidal anti-inflammatory agents.

I hope that I have provided sufficient detail to answer your question.  If 
not, or if I have answered the wrong question, please donít hesitate to ask 
again with a little more background of your problem.

Tom Wilson, MD PhD

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