Kidney function tests often include two terms you may find in your results, namely urea and creatinine. Both are waste products that are normally filtered by the kidneys, so their levels in the blood can give a general picture of how the kidneys are working.
Getting to Know Urea and Creatinine
Put simply, both substances are waste products of the body's processes:
- Urea is a waste product related to the breakdown of protein in the body.
- Creatinine is a waste product related to everyday muscle activity.
Under normal conditions, the kidneys filter out these waste products and remove them through urine. When the filtering ability declines, more of these waste products can remain in the blood, so their levels may rise. From creatinine, an estimate of the kidneys' filtration rate is sometimes also calculated to add to the picture.
Things That Can Affect the Results
Urea and creatinine levels are not determined by the condition of the kidneys alone. Several other things can affect them too, such as how well hydrated the body is or dehydration, muscle mass, diet, and your condition at the time of the test. For this reason, a result outside the reference range does not automatically mean a particular disorder is present.
The reference range for these two tests can also differ between laboratories. In addition, what is considered a normal level can differ depending on each person's condition, so it is best assessed as a whole by a doctor.
How to Respond
- Drink enough fluids as advised before the test if you are asked to.
- Tell your doctor if you are taking any particular medications or supplements.
- Look at the results as a whole, not just a single number.
This article aims to help you understand the urea and creatinine tests in general, not to diagnose or replace a medical assessment. If you have concerns about your kidney test results, it is best to consult a doctor, including a 20FIT doctor, so you can receive an explanation suited to your condition.