What's In Your Urine?

What the heck is creatinine, and more importantly, why do we care?

Medications, once they act on the body, are metabolized and broken down.  Quite often they change form or get stored in fat cells, or any number of other biochemical reactions; however, eventually the waste, or un-metabolized medication, needs to be eliminated from your body.  Some medications are metabolized by your kidney, others by your liver, most by a combination of both your kidney and your liver.

Today, we are discussing the fate of medications whose main route of elimination is through your kidneys.  If a metabolized medication is eliminated from the body through the kidneys, then we better make sure that your kidneys are working as they should.  If the kidneys have a decreased function, then the medication may back up to potentially toxic levels. 

I like to use the analogy of a freeway on ramp.  If the traffic is flowing, then there is no problem merging onto the freeway.  If the traffic slows, then the on ramp gets backed up and cars come to a stop.  It gets very crowded really quick.  At this point, we need to either stop sending cars down the on ramp or open up some more lanes on the freeway before we have a problem. 

So, back to the beginning, what the heck is creatinine?  Creatinine is a chemical waste product in the blood that passes through the kidneys to be filtered and eliminated in the urine.  The chemical waste is a by-product of normal muscle contractions.  Creatinine is made from creatine, a supplier of energy to the muscle.

In general, your creatinine blood levels will remain relatively constant on a day to day basis.  There are a few situations where it may be slightly elevated or lowered based on your gender, age, exercise level or what you are eating; however, rapid fluctuations are usually not the norm. 

An individual with relatively healthy kidneys will filter out creatinine at a regular rate and maintain a relatively constant level of creatinine in their blood serum.  If the kidneys are not functioning so well, then the creatinine may back up and the blood serum levels will increase.  This process allows for a reasonably simple way of monitoring how well the kidneys are functioning. 

If your blood serum level shows a rising level of creatinine, then the doctor may look into what is going on to cause the kidneys to not filter as well.  At this point, your pharmacist gets excited about making sure that the doses of any of your medications that are excreted via the kidneys are decreased so that you don't end up with toxic levels of the medication in your system which may cause some significant/unwanted side effects.

If you take any medications on a regular basis, here is your homework:

                1.  Next time you visit your doctor, ask them how your kidney function is.  If they ask you why you want to know, let them know that you are just concerned about your own health and want to make sure your medications are dosed appropriately for your current kidney function.
                2.  Next time you visit your community pharmacist, ask them which of your medications are eliminated primarily through your kidneys.  If they ask you why, tell them the same thing you told your doctor in #1.


Copyright AudibleRx (TM), all rights reserved. Please do not copy or publish or distribute without consent and approval from AudibleRx (TM).