Creatinine Blood Test in Australia

What Is a Creatinine Blood Test?

A serum creatinine test measures how much creatinine is in your blood. Creatinine is a waste product made continuously as your muscle tissue breaks down through normal breakdown. Healthy kidneys filter creatinine out of your blood and excrete it in urine at a steady rate. Because production stays fairly constant while healthy kidneys filter waste efficiently, rising serum creatinine levels are one of the most widely used signals that your kidneys are working less effectively, which is why it's one of the standard chronic kidney disease tests and renal function tests ordered alongside eGFR.

Creatinine is also the direct input used to calculate eGFR (estimated Glomerular Filtration Rate), the headline kidney function number you'll actually see in your test results. High blood creatinine levels, or blood creatinine that's rising over repeat tests, are what your doctor watches most closely, rather than any single measure creatinine reading in isolation.

What Does Creatinine Measure?

Creatinine levels reflect a balance between two things: how much your muscles are producing, and how efficiently your kidneys are clearing it. This is why creatinine isn't purely a marker of renal function, it also carries information about your muscle mass:

• Kidney filtration: the main driver of a rising result. Reduced filtration lets creatinine build up in your blood, since your kidneys are working less efficiently to clear it out.
• Muscle mass: people with more muscle mass naturally produce more creatinine, and men generally run higher than women for this reason. Decreased muscle mass has the opposite effect. A well-trained adult can have a higher creatinine reading with completely healthy kidneys and normal blood vessels.
• Diet: a large serving of cooked meat shortly before testing can temporarily raise your result, since muscle proteins from food are broken down into related compounds.
• Hydration: dehydration can make creatinine appear higher than it actually is.

How Much Does a Creatinine Blood Test Cost?

Creatinine testing is included as part of your core Everlab blood panel, using the same serum sample as eGFR, urea, sodium, chloride, bicarbonate, and the rest of your kidney and electrolyte markers, at no extra cost. It isn't purchased as a standalone test. Normal levels for creatinine in your blood are covered below.

What Is a Normal Creatinine Level?

Reference ranges vary between laboratories, so always check the specific range printed on your own results. Commonly used adult reference ranges are approximately 60 to 110 µmol/L (about 0.7 to 1.2 mg/dL) for men and 45 to 90 µmol/L (about 0.5 to 1.0 mg/dL) for women, reflecting the fact that men typically carry more muscle mass. A result outside this range doesn't automatically mean kidney disease, age, sex, body size, and muscle mass all shift what's normal for you, which is exactly why we read creatinine alongside eGFR, urea, and the calculated ratios below, rather than on its own.

For eGFR specifically, a result of 90 mL/min/1.73m² or above is generally considered normal, and a result that stays below 60 mL/min/1.73m² for three months or more is the standard definition of chronic kidney disease.

What Causes High Creatinine Levels?

• Chronic kidney disease: reduced filtration capacity that builds up gradually over time.
• Diabetic kidney disease (diabetic nephropathy): a common long-term complication of poorly controlled blood sugar.
• Acute kidney injury, including acute tubular necrosis: a sudden drop in kidney function, which can happen alongside severe muscle breakdown (rhabdomyolysis), certain infections, or reduced blood flow to the kidneys.
• Dehydration or congestive heart failure: both reduce effective blood flow to the kidneys and can temporarily raise creatinine without permanent kidney damage.
• Urinary obstruction (urinary tract blockage), including kidney stones: a blockage that prevents normal filtration and excretion.
• Certain medications: including some NSAIDs and blood pressure medications, which can reduce kidney blood flow. A few other medications (such as trimethoprim) can inhibit tubular secretion of creatinine specifically, raising your result slightly without actually reducing your true filtration rate.
• High muscle mass: a benign explanation in well-trained adults, worth ruling out before assuming a kidney cause.

Is a Creatinine Clearance Test the Same as What Everlab Does?

Not quite. Creatinine clearance is an older creatinine urine test method of assessing kidney function, calculated using both a blood (serum) sample and a urine creatinine measurement, requiring you to collect your urine volume over a full 24 hour urine sample for an accurate measurement. Normal creatinine clearance is generally around 100 to 120 mL/min for healthy men, but because your kidneys secrete a small amount of extra creatinine directly into the urine, this urine test tends to overestimate true kidney filtration by roughly 10 to 20%, as the US National Kidney Foundation and similar bodies note.

Everlab calculates eGFR directly from your blood sample alone, using your creatinine result together with your age and sex, so there's no 24-hour urine collection required. This is now the standard, more convenient approach used in routine kidney function testing. If your doctor ever needs the older creatinine clearance test, or a urine albumin (urine albumin-to-creatinine ratio) test to check how much albumin is passing into your urine, that's arranged separately and isn't part of your standard Everlab blood panel.

What Causes Low Creatinine Levels?

• Low or decreased muscle mass: including age-related muscle loss (sarcopenia), the most common explanation, since less muscle means less normal breakdown of muscle tissue to produce creatinine.
• Malnutrition: reduced protein intake lowers overall creatinine production.
• Muscle-wasting conditions: less common, but a genuine cause worth investigating if unexplained.
• Advanced liver disease: less commonly, since part of creatinine's precursor is produced in the liver, severe liver disease can also lower your result.

What Are the Calculated Ratios We Generate From Your Creatinine Result?

Beyond your raw creatinine number, Everlab calculates three additional ratios automatically from the same blood draw, at no extra cost. Each one adds context that creatinine alone can't give you.

Urea:Creatinine Ratio

This ratio helps tell apart the possible causes of an abnormal urea result. When urea rises disproportionately compared to creatinine, it points to a cause outside the kidneys themselves, such as dehydration, a high-protein diet, or gastrointestinal bleeding. When urea and creatinine rise together in proportion, it points to a genuine kidney-based cause instead. A markedly high ratio is one of the ways we can pick up on internal bleeding that neither marker would flag on its own.

BUN:Creatinine Ratio

Blood Urea Nitrogen (BUN) is calculated directly from your urea result. Comparing it to your creatinine helps distinguish dehydration or reduced blood flow to the kidneys (pre-renal causes) from a problem within the kidneys themselves.

Uric Acid:Creatinine Ratio

This ratio reflects how your kidneys are handling uric acid specifically, giving extra context on kidney handling and urate metabolism alongside your other results.

How Is the Creatinine Blood Test Performed?

Your creatinine result comes from the same blood draw as the rest of your Everlab panel, no separate appointment or extra sample needed. A healthcare professional places a tourniquet above a vein in your arm, cleans the area, and draws blood into a collection tube. The draw itself takes less than five minutes, and the sample is sent to the laboratory for analysis alongside your other markers.

How Do I Prepare for a Creatinine Blood Test?

24 hours before

• Avoid heavy exercise, intense activity increases muscle breakdown and can temporarily raise creatinine.
• Avoid a large serving of cooked meat, since muscle proteins from food can influence your result.

Before your appointment

• Stay well hydrated, dehydration can make creatinine appear higher than it actually is.
• List any medications you're taking, including NSAIDs, blood pressure medications, and creatine supplements, since these can all affect your result.

No fasting is required for creatinine specifically, though if your blood draw includes other fasting-dependent markers as part of your panel, follow the fasting instructions for those instead.

How Does Creatinine Connect to Your Broader Health?

Reduced kidney function doesn't just affect your kidneys. It's associated with increased risk of heart disease, stroke, high blood pressure, fluid retention, anaemia, and bone disease, since your kidneys are involved in regulating blood pressure, producing red blood cells, and supporting bone health, alongside filtering waste. Early kidney changes often cause no symptoms at all, which is exactly why routine testing, rather than waiting for symptoms, is what catches this early. If your results suggest a genuine renal cause, your Everlab doctor can refer you to a kidney specialist (nephrologist) for further diagnostic tests and other tests as needed.

If your doctor is also considering a CTCA (CT Coronary Angiogram) for you, your creatinine and eGFR are checked first, since the contrast dye used in that scan is processed by your kidneys.

Sources:

• ‍Kidney Health Australia

Internationally, similar patient guidance is published by the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the US National Kidney Foundation.

Explore More From Everlab

If kidney and metabolic health are part of a bigger picture for you, these might also be useful:

• Liver Function Test (LFT): the liver panel reviewed alongside your kidney results. Learn more.
• AST Blood Test: another marker read in context, not alone, from the same panel. Learn more.
• CT Coronary Angiogram (CTCA): a scan that requires a recent creatinine and eGFR check before booking. Learn more.
• Blood Pressure, Explained Simply: a major factor in long-term kidney health. Read more.