Creatine is a natural substance produced from amino acids in your body and used to supply energy to all of your cells, especially your muscles. Creatinine is the breakdown product of creatine, and it is excreted in your urine. Measuring creatinine levels in your blood serum and urine can validate suspicion of certain diseases, such as kidney failure and muscle wasting diseases. Vitamin C and certain drugs can alter creatinine levels, usually increasing them, which can lead to misdiagnosis.
Creatine phosphate is produced naturally in your liver and kidneys from amino acids, specifically arginine, glycine and methionine. Once produced, it is transported in your blood for use by muscles and other tissues. According to the book “Advanced Nutrition: Macronutrients, Micronutrients and Metabolism,” about 95 percent of your body's total creatine is located in skeletal muscle, where it is used to increase the formation of ATP, your body’s energy storage molecule. Creatine is recycled regularly, and its primary breakdown product is creatinine.
Creatinine is produced at a fairly constant rate by your body and is filtered out of the blood mainly by your kidneys. If the filtering mechanism of your kidneys is deficient, creatinine blood levels rise. If you have a muscle wasting disease, such as muscular dystrophy, or have suffered trauma to your muscles, there will be higher levels of creatine in your urine. Creatinine levels in your blood and urine may be used to calculate your total creatinine clearance. According to the “Textbook of Medical Physiology,” men tend to have higher levels of creatinine because they have more skeletal muscle mass than women, although all vegetarians have low levels.
Measuring serum creatinine is a simple test, and it is the most commonly used indicator of renal function. Normal reference ranges for serum creatinine are 0.5 to 1.0 mg/dL for women, as cited in the text, “Human Biochemistry and Disease.” An inactive elderly female may have levels a little less than 0.5 mg/dL. Some substances, such as vitamin C, can alter creatinine levels.
Vitamin C and Creatinine
According to “Vitamins: Fundamental Aspects in Nutrition and Health,” taking supplemental vitamin C usually elevates your blood serum creatinine levels and clearance creatinine levels, although this is heavily dependent on dosage, lifestyle and health status. A Turkish study published in a 2005 edition of “The Tohoku Journal of Experimental Medicine” found that supplemental vitamin C reduced creatinine levels in rats with kidney disease due to its protective and oxidative effects. Thus, vitamin C may help reduce creatinine levels if you have a kidney disease, but raise the levels if you are relatively healthy.
Many other factors can increase your creatinine levels that don’t signify either kidney or muscle disease, such as taking diuretics or antibiotics, eating red meat, strenuous exercise, being in a car accident, dehydration or having gout, notes “Medical Nutrition and Disease.”
- Advanced Nutrition: Macronutrients, Micronutrients, and Metabolism; Carolyn D. Berdanier
- Textbook of Medical Physiology – Tenth Edition; Arthur C. Guyton, et al.
- Human Biochemistry and Disease; Gerald Litwack
- Vitamins: Fundamental Aspects in Nutrition and Health; G. Combs
- The Tohoku Journal of Experimental Medicine: Protective Effects of Vitamin C, Alone or in Combination with Vitamin A, on Endotoxin-Induced Oxidative Renal Tissue Damage in Rats
- Medical Nutrition and Disease: A Case-based Approach; Lisa Hark
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.