Your kidneys filter about 180 litres of blood every day, removing waste and balancing water, salt and minerals. Chronic kidney disease (CKD) is increasingly common in India, driven largely by diabetes and high blood pressure, and it often causes no symptoms until a large part of kidney function is lost. A kidney function test (KFT or RFT) helps catch problems early.
What the test includes
| Test | Typical adult range |
|---|---|
| Serum creatinine | Men about 0.7 – 1.3 mg/dL; women about 0.6 – 1.1 mg/dL |
| Blood urea | about 15 – 45 mg/dL |
| BUN (blood urea nitrogen) | about 7 – 20 mg/dL |
| Sodium | 135 – 145 mmol/L |
| Potassium | 3.5 – 5.0 mmol/L |
| Uric acid | See our separate uric acid guide |
Creatinine
Creatinine is a waste product from muscles. When kidneys slow down, creatinine builds up in the blood. However, it also depends on muscle mass: a muscular young man may have a higher normal value than a thin elderly woman. That is why doctors rely more on eGFR.
eGFR: the most useful number
The estimated glomerular filtration rate is calculated from creatinine, age and sex, and estimates how well your kidneys filter blood (in mL/min/1.73 m²).
| eGFR | Meaning |
|---|---|
| 90 or above | Normal (if no other signs of kidney damage) |
| 60 – 89 | Mildly reduced, common with ageing |
| 45 – 59 | Mild to moderate decrease |
| 30 – 44 | Moderate to severe decrease |
| 15 – 29 | Severely reduced |
| Below 15 | Kidney failure |
Chronic kidney disease is generally diagnosed when eGFR stays below 60 for three months or more, or when there are other signs of kidney damage such as protein in the urine.
Urine albumin: the early warning
The urine albumin-to-creatinine ratio (UACR) detects small amounts of protein leaking into the urine, often the earliest sign of diabetic or blood pressure-related kidney damage. A value below 30 mg/g is considered normal. People with diabetes or hypertension should have this test regularly.
What can raise urea and creatinine temporarily?
- Dehydration, fever or vomiting
- A very high-protein meal or supplements
- Intense exercise
- Some medicines
A single high reading is often repeated before any conclusions are drawn.
How to protect your kidneys
- Keep blood sugar and blood pressure well controlled.
- Avoid frequent use of painkillers such as ibuprofen and diclofenac without medical advice.
- Be cautious with unregulated herbal or "detox" products.
- Drink enough water, especially in hot weather.
- Limit salt and processed foods.
- Do not smoke, and stay at a healthy weight.
Who should get tested?
Anyone with diabetes, high blood pressure, heart disease, a family history of kidney disease or age over 60 should have a kidney function test and urine albumin check at least once a year, or as advised by their doctor.
Lab Tests Explained: the full series
- Part 1: CBC (Complete Blood Count)
- Part 2: Lipid Profile
- Part 3: Liver Function Test
- Part 4: Kidney Function Test (you are here)
- Part 5: Urine Routine Test
- Part 6: Iron Studies and Ferritin
- Part 7: Vitamin B12
- Part 8: Full-Body Checkup by Age
Related reads: Blood sugar levels and HbA1c · Thyroid tests · Vitamin D test · Uric acid
Disclaimer: This article is for general information only and is not medical advice. Reference ranges vary between laboratories, so always read your report against the range printed on it and discuss results with a qualified doctor.
