Creatinine is measured in a routinely ordered blood test, and it’s a reflection of general metabolic health. Normal creatinine bloods levels for men are about 0.6 to 1.2 milligrams/deciliters (mg/dL) and 0.5 to 1.1 mg/dL for women. Creatinine is a chemical waste product found in the blood — a byproduct of normal, everyday muscle contractions. Under normal conditions, it’s filtered by the kidneys and removed from the body through urination.
Temporary elevated levels may occur, regardless of kidney function, due to taking certain supplements or medications, dehydration, consuming large amounts of meat or protein or through building muscle through heavy weight training.
Kidney Disease and High Creatinine Levels
Abnormally high levels of creatinine may indicate kidney damage or chronic kidney disease. Functional damage to the kidneys can be due to a serious infection or low blood flow to the kidneys. Reduced blood flow or low blood pressure can be a result of heart failure, artery disease or severe dehydration.
Another cause is the loss of the architectural units where filtration is performed — the glomerulus. An increase in blood creatinine and reduced excretion are signs of lost kidney glomerular function — or glomerular filtration rate. Diseases that affect the microscopic blood vessels in the glomerulus, such as diabetes, or inflammatory or autoimmune diseases of the kidney, such as lupus, can damage the delicate structures involved in kidney filtration. Some inherited conditions (such as Goodpasture syndrome), response to infectious agents (such as Streptococcus) and damage caused by medications can also reduce kidney function.
Other conditions that can lead to damage include:
Shock resulting in blood loss
Symptoms of High Creatinine Levels
Some people with high creatinine levels may experience the following symptoms:
Shortness of breath
Factors That Can Affect Creatinine Test Results
1. Medications: phenytoin, vitamin C, diuretics, some antibiotics, cimetidine and quinine
2. Doing strenuous exercise two days before testing
3. Eating high amounts of meat (eight ounces) within 24 hours of testing
Urinary Tract Obstruction and High Creatinine Levels
Another way kidney filtration may be impaired is when something obstructs urine flow from the kidney. A blockage in the urinary tract, especially the ureter (which transfers fluid from the kidney to the bladder), the bladder itself or the urethra, will obstruct the flow. Conditions that may block the urinary system include kidney stones, congenital obstructions, post-injury or postsurgical scarring, poor bladder emptying (aka benign prostatic hypertrophy—BPH) or due to prostate cancer. Blood test results are typically normal — especially if there is only partial obstruction — but tests may reveal high levels of creatinine if there has been a complete obstruction for more than several hours.
Sources of Creatinine
In addition to production in the skeletal muscle of the body, creatine and creatinine are also present in the diet in meat. Vegetarians have lower intake of these substances than people eating a diet high in animal flesh, especially beef. Creatine is a molecule that acts as a muscle’s store of energy and breaks down into creatinine. People seeking to enhance muscle performance sometimes take creatine supplements, such as creatine salts or creatine esters. High intake of dietary or supplemental sources of creatine may increase the rate of creatinine production, elevate plasma creatinine and increase creatinine in the urine.
- Clinical Chemistry: Serum Creatinine as an Index of Renal Function -- New Insights Into Old Concepts
- The Netherlands Journal of Medicine: Elevated Plasma Creatinine Due to Creatine Ethyl Ester Use
- National Kidney and Urologic Diseases: Glomerular Disease
- The National Institute of Standards and Technology: Development of Reference Measurement Procedures and Reference Materials for Creatinine