Creatinine measurement is used to diagnose and monitor the treatment of acute and chronic kidney diseases, to regulate the dosage of drugs excreted by the kidneys, and to monitor kidney transplant recipients.
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Creatinine is the non-protein end product of anaerobic energy production from creatine phosphate metabolism in skeletal muscle. Creatinine is produced continuously and is completely excreted by the kidneys. Creatinine levels are mainly influenced by renal function, so measuring creatinine is a very useful tool in assessing renal function.
Elevated creatinine levels indicate a slowdown in glomerular filtration. Since creatinine levels remain stable even as we age, this test is particularly useful in assessing renal impairment during which a large number of nephrons are destroyed. Creatinine concentration is usually determined in conjunction with blood urea to assess renal function. The normal ratio of creatinine to blood urea nitrogen ranges from 6:1 to 20:1. Blood creatinine levels are also used to monitor patients taking drugs known to be nephrotoxic, such as aminoglycosides.
Serum creatinine values are 20-40% higher in the late afternoon compared to morning measurements in the same patient.
Possible Interpretations of Pathological Values
- Increase: Acromegaly, allergic purpura, amyloidosis, analgesic abuse, azotemia (renal or metastatic etiology), congenital hypoplastic kidneys, congestive heart failure, diabetes mellitus, diet (high in meat), gigantism, chronic glomerulonephritis, Goodpasture's syndrome, gout, hemoglobinuria, high dietary intake, shock, hypothyroidism, infants (first 2 weeks of life), intestinal obstruction, Kimmelstiel-Wilson syndrome, metal poisoning, multiple myeloma, muscular destruction, nephropathy (hypercalcemic, hypokalaemic), nephrosclerosis, necrotic pancreatitis, necrotic polyarteritis, polycystic disease, preeclampsia, pyelonephritis, stenosis or renal artery thrombosis, renal cortical necrosis, renal failure, renal vein thrombosis, renal tuberculosis, rheumatoid arthritis, scleroderma, sickle cell anemia, acute bacterial endocarditis, systemic lupus erythematosus, testosterone therapy, toxic shock syndrome, uremia, urinary obstruction, vomiting. Medications: acetohexamide, acyclovir, ammonia, amphotericin B, androgens, arginine, bleomycin, captopril, cephalosporins (cefoxitin, cephalexin), cimetidine, clofibrate, corticosteroids, diacetic acid, diuretics, phosphate, disopyramide, dopamine, fenofibrate, fosinopril, fructose, gentamicin sulfate, glucose, hydralazine hydrochloride, hydroxyurea, lithium carbonate, losartan, mannitol, sodium meclofenamate, methicillin, metoprolol tartrate, minoxidil, mitramycin, nitrofurantoin, nitrous oxide (inhaled), propranolol, proteins, pyruvate, sulfobromophthalein, sulfonamides, streptokinase, testosterone, triamterene biomycin. Herbal or natural treatments with products containing aristolochic acids.
- Decrease: Diabetic ketoacidosis (artificial reduction), muscular dystrophy. Medications: Cefoxitin, cimetidine, chlorpromazine, chlorprothixene, marijuana, thiazide diuretics, vancomycin. Herbal or natural remedies that include Cordyceps sinensis.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
