What is the normal level of Creatine (Creatinine)?

From the Guidelines

Normal creatine levels in the blood typically range from 0.6 to 1.2 mg/dL (53 to 106 μmol/L) for men and 0.5 to 1.1 mg/dL (44 to 97 μmol/L) for women. However, it's essential to note that creatine levels are not commonly measured in clinical practice; instead, creatinine (a breakdown product of creatine) is more frequently monitored as a marker of kidney function 1. The serum creatinine concentration is affected by factors other than GFR, such as creatinine secretion and generation and extrarenal excretion, resulting in a relatively wide range for serum creatinine in normal persons 1.

Key Points to Consider

• Creatine is a naturally occurring compound found primarily in muscle tissue and is used to supply energy to cells, particularly muscle cells.
• The body produces creatine in the liver, kidneys, and pancreas, and it can also be obtained through diet, mainly from meat and fish.
• Elevated creatine levels may occur with certain muscle disorders or kidney dysfunction, while lower levels might be seen in conditions affecting muscle mass.
• For those supplementing with creatine for athletic performance, typical dosing involves a loading phase of 20 grams daily (divided into 4 doses) for 5-7 days, followed by a maintenance dose of 3-5 grams daily, though supplementation does not require blood level monitoring in healthy individuals.
• The use of GFR (rather than serum creatinine measurement) to characterize kidney function is a critical element in the Working Group's strategy for improving care of patients with chronic kidney disease 1.

Clinical Implications

• Clinical laboratories should report an estimate of GFR using a prediction equation in addition to reporting the serum creatinine measurement 1.
• Autoanalyzer manufacturers and clinical laboratories should calibrate serum creatinine assays using an international standard 1.
• The MDRD Study equation shows a tighter correlation with measured GFR than 24-hour creatinine clearance 1.

Recommendations

• Clinicians should not use serum creatinine concentration as the sole means to assess the level of kidney function 1.
• Use of GFR values can encourage the public and patients to “know their number,” in much the same way that they have become familiar with their blood pressure or cholesterol measurements 1.

From the Research

Normal Creatine Levels

• The normal level of creatine in the body is not explicitly stated in the provided studies, but it can be inferred that creatine levels are affected by various factors such as diet, muscle mass, and kidney function 2, 3.
• Creatine supplementation can increase creatinine levels, which may act as a false indicator of renal dysfunction 2.
• The average omnivorous diet cannot fully compensate for the daily losses of creatine, and endogenous synthesis of creatine is required for continuous replenishment 3.

Factors Affecting Creatine Levels

• Kidney function: Creatine levels may be affected by kidney function, and individuals with kidney disease may have decreased endogenous creatine production 3.
• Diet: Creatine levels can be influenced by dietary intake, particularly from meat and dairy products 3.
• Muscle mass: Creatine levels may be related to muscle mass, and individuals with muscular dystrophies or other muscle disorders may have altered creatine levels 4.

Safety and Efficacy of Creatine Supplementation

• Creatine supplementation is generally considered safe and well-tolerated in healthy individuals and in patients with certain muscle disorders 2, 5, 4, 6.
• High-dose creatine supplementation may be associated with adverse effects, such as increased muscle pain and impaired activities of daily living, in certain individuals 4.
• Creatine supplementation may have benefits beyond muscle strength, including enhanced postexercise recovery, injury prevention, and potential neurologic benefits 6.