6 values
KFT: Reading a Kidney Function Test
A kidney function test asks two separate questions: how well the kidneys are clearing waste, and whether the body's salts are in balance. Urea and creatinine answer the first; sodium, potassium and calcium the second.
When it is ordered
Ordered in diabetes and high blood pressure, before certain medicines and scans, and in routine check-ups. Fasting is not usually required.
Every line on the report
| Test | Typical range | Unit | What it is |
|---|---|---|---|
| Blood Urea | 15–40 | mg/dL | Waste from protein, cleared by the kidneys — but also raised by dehydration and a high-protein diet. |
| Creatinine | 0.6–1.1 (F) · 0.7–1.3 (M) | mg/dL | The more reliable of the two kidney markers, because diet moves it far less. |
| Uric Acid | 2.6–6 (F) · 3.5–7.2 (M) | mg/dL | Raised levels can crystallise in a joint and cause gout, classically in the big toe. |
| Sodium | 136–145 | mEq/L | Salt balance, tied to how much water the body is holding. Moved by vomiting, diarrhoea and some medicines. |
| Potassium | 3.5–5.1 | mEq/L | Matters for the heart's rhythm, which is why a markedly abnormal value is acted on quickly. A tight squeeze during the blood draw can falsely raise it. |
| Calcium | 8.6–10.2 | mg/dL | Bone and nerve function. Read alongside vitamin D, which is widely deficient in India. |
Ranges differ between laboratories. These are the values commonly printed on adult reports in India — always compare against the range printed on your own report, next to your own result.
How the values are read together
- Urea with creatinine — urea alone is unreliable, because dehydration and a high-protein diet both raise it. Creatinine is steadier, and the two together separate a kidney problem from a hot afternoon.
- eGFR — many reports calculate this from creatinine, age and sex. It is usually the number a doctor actually looks at.
- The salts — sodium and potassium move with illness, medicines and fluid loss, and a markedly abnormal potassium is acted on quickly because of its effect on heart rhythm.
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Frequently asked questions
What is a normal creatinine level?
Roughly 0.6–1.1 mg/dL for women and 0.7–1.3 mg/dL for men, varying by lab and by muscle mass. Your report's own range is the one to use.
Can dehydration affect a kidney test?
Yes, noticeably. Being short of fluid raises urea more than creatinine, and that pattern is one of the things a doctor looks for before concluding anything about the kidneys.
Is a slightly raised uric acid a problem?
Often not by itself. It matters most when it comes with joint pain, or alongside other risks, and it is managed with diet and, where needed, medicine a doctor prescribes.