What is Serum Creatinine?
Creatinine is a waste product generated from the normal breakdown of creatine, a molecule found in your muscles that helps produce energy. Your body produces creatinine at a fairly constant rate, and it is filtered out of the blood by the kidneys and excreted in urine.
When your kidneys are not working properly, they cannot filter creatinine efficiently, causing its levels to rise in the blood. The serum creatinine test measures the amount of creatinine in your blood and is one of the most important tests for assessing kidney function.
Why is This Test Done?
- To assess kidney function and detect kidney disease early
- To monitor known kidney conditions (chronic kidney disease, kidney transplant patients)
- To evaluate kidney function before prescribing medications that are cleared by the kidneys
- To monitor the effects of medications that can affect the kidneys (NSAIDs, certain antibiotics, ACE inhibitors)
- To screen patients with diabetes or hypertension, as these are leading causes of kidney damage
- As part of a routine health check-up, especially for individuals over 40
How to Prepare for the Serum Creatinine Test
Simple Preparation
- No fasting is usually required. You can eat and drink normally.
- Stay well hydrated — drink your usual amount of water. Dehydration can temporarily raise creatinine levels.
- Avoid heavy meat consumption the day before the test, as a large protein-rich meal can slightly raise creatinine.
- Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily increase creatinine.
- Inform your doctor about all medications, especially NSAIDs (ibuprofen, diclofenac), antibiotics, and supplements containing creatine.
Understanding Your Results
| Level | Males (mg/dL) | Females (mg/dL) | What It Means |
|---|---|---|---|
| Normal | 0.7 - 1.3 mg/dL | 0.6 - 1.1 mg/dL | Kidneys are filtering blood normally. |
| Mildly Elevated | 1.3 - 2.0 mg/dL | 1.1 - 1.8 mg/dL | May indicate early kidney impairment. Could also be due to dehydration, high protein diet, or muscle mass. |
| Moderately Elevated | 2.0 - 5.0 mg/dL | 1.8 - 5.0 mg/dL | Significant kidney dysfunction. Further evaluation and treatment needed. |
| Severely Elevated | Above 5.0 mg/dL | Above 5.0 mg/dL | Severe kidney failure. May require urgent intervention, including dialysis. Seek immediate medical attention. |
eGFR (Estimated Glomerular Filtration Rate)
Your laboratory report will often include an eGFR value, which is calculated from your serum creatinine along with your age, sex, and race. The eGFR gives a more accurate picture of kidney function than creatinine alone and is used to stage chronic kidney disease (CKD).
| CKD Stage | eGFR (mL/min/1.73m²) | Kidney Function | Action |
|---|---|---|---|
| Stage 1 | 90 or above | Normal or high | Monitor if risk factors present. Manage diabetes and blood pressure. |
| Stage 2 | 60 - 89 | Mildly decreased | Monitor regularly. Control risk factors (blood sugar, blood pressure). |
| Stage 3a | 45 - 59 | Mildly to moderately decreased | Referral to a specialist may be needed. Dietary modifications recommended. |
| Stage 3b | 30 - 44 | Moderately to severely decreased | Specialist care recommended. Medication review and dietary management essential. |
| Stage 4 | 15 - 29 | Severely decreased | Preparation for possible dialysis or transplant. Close specialist monitoring. |
| Stage 5 | Below 15 | Kidney failure | Dialysis or kidney transplant usually required. |
Risk Factors for Kidney Disease in Sri Lanka
Sri Lanka has some unique kidney health challenges. The following are important risk factors:
- Diabetes mellitus: The leading cause of CKD worldwide and in Sri Lanka. Uncontrolled blood sugar damages the tiny blood vessels in the kidneys over time.
- Hypertension (high blood pressure): The second leading cause of CKD. Persistent high blood pressure damages kidney arteries and reduces filtration capacity.
- Overuse of NSAIDs: Pain killers such as ibuprofen, diclofenac, and mefenamic acid are widely available and commonly used. Long-term or excessive use can cause significant kidney damage.
- Dehydration: Sri Lanka's hot and humid climate, combined with outdoor labour, can lead to chronic dehydration, which stresses the kidneys over time.
- CKDu (Chronic Kidney Disease of unknown etiology): A unique form of kidney disease found predominantly in farming communities in the North Central, North Western, Uva, and Eastern provinces of Sri Lanka. It is not linked to diabetes or hypertension. Possible causes being studied include agrochemical exposure, contaminated water (heavy metals such as cadmium and arsenic), and heat stress. CKDu has affected thousands of Sri Lankan farmers and is a major public health concern.
- Herbal and ayurvedic preparations: Some traditional remedies may contain heavy metals or nephrotoxic substances. Always inform your doctor about any herbal products you use.
What Should You Do Next?
- Normal creatinine and eGFR: Continue healthy habits. Stay hydrated, maintain a balanced diet, control blood sugar and blood pressure, and avoid unnecessary NSAIDs.
- Mildly elevated creatinine: Your doctor will likely order a repeat test and additional investigations (urine test, ultrasound) to determine the cause.
- Moderately elevated creatinine: Referral to a nephrologist (kidney specialist) may be recommended. Dietary modifications, medication adjustments, and close monitoring are essential.
- Severely elevated creatinine: This is an urgent situation. Seek immediate medical care. Dialysis may be required.
Important: A single creatinine result should be interpreted in context. Muscle mass, hydration, diet, and medications all influence creatinine levels. Your doctor will consider these factors along with your eGFR, urine tests, and clinical symptoms to assess your kidney health. Never self-diagnose based on creatinine alone.