Showing normal creatinine levels mean that your kidneys are well functioning and are not taking hits from factors that may overload the kidney function such as drugs, medications and certain medical conditions.
Since creatinine is filtered out of the blood by the kidneys to then be excreted in urine, it acts as an important biomarker to assess and monitor kidney function. When the kidneys are not functioning properly, filtration of waste products is not functioning properly, resulting in increased levels of creatinine levels in your blood.
There are therefore three main reasons to measure creatinine:
To diagnose and reveal kidney disease
To monitor and evaluate kidney function
To adjust dosages of medications eliminated or secreted by the kidneys
Measuring creatinine is most often part of a routine procedure in monitoring those conditions that may damage the kidneys if not treated right. The three most common conditions are:
Kidney disease
High blood pressure
Diabetes
Creatinine is a waste product normally produced in our muscles, excreted in urine and used in medicine to monitor and evaluate kidney function. Creatinine is born out of the breakdown of something called creatine phosphate, an energy reserve for the muscles, especially during high-intensity exercise.
High levels of creatinine indicates decreased kidney function, since malfunctioning kidneys fail to excrete creatinine in urine -> the levels of creatinine in blood build up.
Important note: There are several causes for increased creatinine levels that are not due to a loss in kidney function. Read more about it in what can increase levels of creatinine?
There are several conditions that can cause high levels of creatinine, such as:
Decreased kidney function
If kidneys are unable to properly filter out the creatinine in our bloodstream, the levels will rise. Examples of conditions causing a decrease in function include acute kidney injury, chronic kidney disease and urinary tract obstruction.
Dehydration
When you are dehydrated, the blood becomes more concentrated and less blood will flow to the kidneys. As a direct result, less creatinine is filtered out of the blood, which can cause an increase in creatinine levels.
Circulatory conditions
Such as heart failure, may cause the same lack of blood flow to your kidneys as dehydration, resulting in a possible increase in creatinine levels.
High-protein diet
Eating a diet rich in proteins can increase the production of creatinine (through increased breakdown of creatine phosphate) Includes supplements rich in protein or creatine
High-intensity exercise
High-intensity exercise as well as muscle injury can increase levels of creatinine, through the breakdown of muscle tissue which releases creatinine into the bloodstream
If you have a lot of muscle mass through strenuous exercise, the function is the same - a lot of muscles means a lot of possible muscle breakdown -> increased levels of creatinine.
Medicines
Some medications such as antibiotics and NSAIDs, can elevate levels of creatinine by either inhibiting kidney function or causing kidney damage.
Low levels of creatinine in blood most often has a low clinical significance. This implies that there is no need for concern.
If you show very low levels of creatinine, it can have to do with either very low levels of muscle mass, caused by malnutrition, immobilization or muscle disease, medications such as corticosteroids. In less common cases, liver disease may result in low creatinine levels since the liver plays an important part in the metabolism of creatinine.
Since muscle mass can highly affect creatinine levels, individual differences are normal, but in general, a normal creatinine level for men is said to be 65-105 micromol/liter (µmol/L).