Creatinine is a waste product which is produced by muscles when they break down creatine. It is excreted from the body by our kidneys in urine. Therefore, the levels of creatinine can give a good indication of how effectively the kidneys are working.
Creatinine is removed from the body as a waste product by the kidneys. It is used in a kidney function test called the estimated glomerular filtration rate (eGFR). The eGFR is used to measure how well the kidneys are working. The kidneys have tiny filters within them called glomeruli – these help to filter our blood and remove waste products.
Creatinine levels can vary between different individuals. For example, those with higher muscle mass will have increased creatinine levels which may give an inaccurate result or may show the results are outside of normal parameters. As well as this, creatinine and eGFR levels will rise after periods of intense exercise but following adequate recover these should return to normal.
High levels of creatinine can be indicative of a reduced kidney function. Symptoms of kidney disease can vary but may include:
However, high levels of creatinine may also be associated with muscle injury. If your levels are high because you have an injury or been involved in intense exercise they should naturally return to normal after a recovery period.
Low levels of creatinine are not as common and are usually not a cause for concern. Women who are pregnant can have low creatinine levels and those with low muscle mass may also have reduced creatinine levels, too.
Although Creatinine is associated with increased kidney function decline, it is possible to see some improvement. If your levels are mildly low, it may be possible to see improvements by making some changes to your lifestyle.
Eating a healthy, balanced diet could also contribute to an improvement in eGFR values. A study by Miyatake et al., (2011) found that eGFR could be improved through lifestyle changes including a reduction in abdominal circumference. A greater waist to hip ratio can mean you are at greater risk of decreased filtration. You should keep your salt intake low – less than 6g per day.
The Mediterranean diet is associated with a reduced risk of chronic kidney disease as well as other medical conditions. The Mediterranean diet is classified by a high intake of vegetables, fruit, legumes, nuts, cereals and olive oil, a low intake of dairy products, saturated fats, meat and poultry. Instead, the diet encourages a moderate intake of fish and has been linked to a reduced risk of mortality.
Exercise is an important factor in a healthy lifestyle. In general, most people should aim to carry out around 150 minutes of aerobic exercise every week. Exercises may include walking, jogging, swimming, cycling, team sports and tennis. However, you should spread the amount of exercise over a few days.
A study has shown that patients who have cardiovascular disease and chronic kidney disease could improve their renal function with exercise therapy.
 Weis, L., Metzger, M and Haymann, J, P et al., (2013). Renal Function Can Improve at Any Stage of Chronic Kidney Disease. PLOS One.
 Miyatake, N., Shikata, K., Makino, H and Numata, T. (2011). Decreasing Abdominal Circumference is Associated with Improving Estimated Glomerular Filtration Rate (eGFR) with Lifestyle Modification in Japanese Men: A Pilot Study. Acta Medica Okayama: 65(6), pp 363-367.
 Huang, X., Jiménez-Moleón and Lindholm, B et al., (2013). Mediterranean Diet, Kidney Function, and Mortality in Men with CKD. Clinical Journal of the American Society of Nephrology: 13(5).
 Toyama, K., Sugiyama, S and Oka, H et al., (2010). Exercise Therapy Correlates with Improving Renal Function Through Modifying Lipid Metabolism in Patients with Cardiovascular Disease and Chronic Kidney Disease. Journal of Cardiology: 56, pp 142-146.