Creatinine is a waste product produced by normal muscle wear and tear. When converting food into energy, the body produces creatine, a molecule that is essential for muscle cells. Creatine is then broken down into creatinine at a relatively constant rate.

It is eliminated from the blood by the kidneys and then excreted in the urine. This process makes it a reliable indicator of kidney health.

Creatinine function

Creatinine has no active role in the body, but monitoring it is crucial to assess kidney health.

• Healthy kidneys : Effectively filter creatinine, releasing it into the urine.
• Damaged kidneys : Accumulate creatinine in the blood, indicating impaired filtration.

Test methods

1. Blood Test (Serum Creatinine) :
   A blood test is the most common method for assessing creatinine levels and kidney function.
   • Included in a basic metabolic panel (BMP) Or a comprehensive metabolic panel (CMP).
   • A blood sample is taken, usually from the arm, and analyzed in the laboratory.
2. Urine Test (24 Hour Urine Collection) :
   This test involves collecting all the urine produced over 24 hours for a complete analysis of kidney function.
   • Measures the total volume and quantity of creatinine excreted in the urine.

Preparations for the Test

• Hydration : Maintain normal fluid intake.
• Diet : Avoid meals that are high in protein (meat) before the test, as they may temporarily increase creatinine.
• Physical Activity : Avoid strenuous exercise 24 hours before the test.
• Medications : Tell your doctor about treatments or supplements taken.

Normal Creatinine Levels

In the blood

• Adult men : 0.74 to 1.35 mg/dL (65.4 to 119.3 µmol/L).
• Adult women : 0.59 to 1.04 mg/dL (52.2 to 91.9 µmol/L).

In the Urine

• Hommes : 0.8 to 1.8 g/day (7 to 16 mmol/day).
• Women : 0.6 to 1.6 g/day (5.3 to 14 mmol/day).

Normal ranges may vary depending on the laboratories and methods used.

Factors Increasing Levels

• Meat-rich diet : Increases creatinine production.
• Creatine Supplements : Contribute to a temporary increase.
• Intense exercise : Causes increased muscle degradation.
• High Muscle Mass : More common among bodybuilders.
• Some medications : Like cimetidine, ritonavir, or trimethoprim.

Factors Reducing Levels

• Vegetarian/Vegan Diet : Decreases creatinine production.
• Low muscle mass : Common in the elderly or in cases of muscular atrophy.
• Pregnancy : May lower levels due to increased blood flow.
• Serious liver diseases : Reduce creatine synthesis.

Interpreting the Results

Creatinine levels should be interpreted by a health professional, who will take into account your overall condition, symptoms, and other tests to provide a comprehensive assessment.

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High Creatinine Levels

Causes

• Kidney disease : Chronic kidney failure (CKD) or acute renal failure (ARI) impedes creatinine filtration.
• Dehydration : Reduces blood dilution, temporarily increasing levels.
• High protein diet : Increases metabolic production.
• Intense exercise : Causes a temporary increase.

Associated symptoms

• Tiredness and weakness.
• Oedemas (legs, ankles).
• Changes in urinary habits (frequency or reduced volume).
• Nausea and vomiting.

Implications

• Kidney failure : May require dialysis or a transplant.
• Hypertension : May worsen kidney damage.
• Heart diseases : Kidney dysfunction increases cardiovascular risk.

Low creatinine levels

Causes

• Reduced muscle mass : Common among the elderly.
• Malnutrition : Causes a drop in production.
• Severe Liver Disease : Affects creatine synthesis.

Associated symptoms

• General weakness.
• Weight loss.
• Edemas in cases of serious liver diseases.

Implications

• Muscular dystrophy : Progressive loss of muscle mass.
• Hepatic disease : May cause numerous metabolic complications.

Dietary changes

• Reduce protein : Limit red meat to avoid metabolic overload.
• Increase fiber : Promotes kidney health.
• Drink Enough Water : Good hydration improves the elimination of waste.
• Limit salt : Reduces blood pressure and protects the kidneys.

Lifestyle Changes

• Moderate exercise : Maintain physical activity without excess to maintain muscle and kidney health.
• Avoid NSAIDs : Anti-inflammatory drugs may affect kidney function.
• Monitor Blood Pressure : Essential for the prevention of chronic kidney damage.
• Regular checks : Detect anomalies early through regular testing.

Proactively managing creatinine levels can prevent serious complications and promote optimal kidney health.