Sample Type

Serum (blood sample)

Fasting Required

❌ Not necessary

Typical Reference Range

0.6 – 1.3 mg/L (may vary slightly by lab)

Test Method

Nephelometry / Immunoturbidimetry

Department

Clinical Biochemistry / Nephrology

Estimating GFR (alternative to creatinine)

Detects early kidney impairment

Chronic Kidney Disease (CKD) monitoring

Especially stage 1 and 2 when creatinine is normal

Kidney transplant recipients

Monitoring allograft function

Heart failure patients

Cystatin-C is a cardiovascular risk marker too

Diabetic nephropathy

Early indicator before creatinine rises

Affected by muscle mass

❌ No

✅ Yes

Affected by diet

❌ No

✅ Yes (e.g., meat intake)

Early CKD detection

✅ Better

❌ Less sensitive

Standardized testing

✅ Available

✅ Available

Low (< 0.6 mg/L)

May be normal or reduced production

Normal (0.6–1.3 mg/L)

Likely normal GFR if consistent with clinical picture

High (> 1.3 mg/L)

Possible kidney dysfunction, reduced GFR

Serum Creatinine

Standard kidney function test

eGFR (Creatinine and/or Cystatin-C based)

Most accurate renal filtration estimate

BUN (Blood Urea Nitrogen)

Assesses renal clearance

Urine Albumin/Creatinine Ratio (ACR)

Detects early glomerular damage

Electrolytes (Na⁺, K⁺, Cl⁻, HCO₃⁻)

Renal electrolyte regulation

Sample Type

Serum (blood)

Fasting Needed

No

Primary Organ

Kidney

Used For

Kidney function estimation, GFR, early CKD

Better than Creatinine?

Yes, in many specific clinical scenarios

Add-On Tests

Creatinine, eGFR, ACR, Electrolytes