KFT: the kidney function test, line by line
What does a KFT actually test?
Your kidneys do two jobs at once. They clear waste out of the blood, and they hold the balance of water, salts and minerals steady. A kidney function test looks at both, which is why the report has two obvious halves.
The clearance half is urea, creatinine and uric acid — leftovers from protein, muscle and cell turnover. When filtering slows, they build up in the blood, so a rise is an indirect measurement: you are reading what did not leave. The balance half is sodium, potassium, chloride, calcium and phosphorus, and those numbers stay in remarkably tight ranges when things are working. A potassium that drifts is a different kind of signal from a creatinine that drifts, and it is often the more urgent one.
What does each line on a KFT mean?
Analyzers and methods vary, so the range printed beside your own result is the one that applies to you. These are the values a typical adult report carries.
| Line | Usual adult range | Half | What moves it |
|---|---|---|---|
| Blood urea | 15 – 40 mg/dL | Clearance | Rises with dehydration and a high-protein day as readily as with slow filtering, so it is the twitchier of the two waste markers |
| Creatinine | 0.7 – 1.3 mg/dL men 0.6 – 1.1 mg/dL women | Clearance | Comes from muscle, so build and sex shift it. Steadier than urea, which is why it anchors the panel |
| eGFR | 90 and above | Calculated | Not measured — computed from creatinine, age and sex. Below 60 held for three months is the figure doctors use when staging kidney disease |
| Uric acid | 3.4 – 7.0 mg/dL men 2.4 – 6.0 mg/dL women | Clearance | Genuinely different by sex. Alcohol, red meat, organ meat and low water intake all push it up |
| Sodium | 136 – 145 mmol/L | Balance | Really a water measurement. Vomiting, diarrhoea, heat and some blood-pressure medicines move it |
| Potassium | 3.5 – 5.1 mmol/L | Balance | The one with the tightest tolerance, because heart rhythm depends on it. A squeezed or delayed sample can read falsely high |
| Chloride | 98 – 107 mmol/L | Balance | Read with sodium and bicarbonate rather than alone; it helps a doctor place an acid-base picture |
| Calcium | 8.6 – 10.2 mg/dL | Balance | Depends on albumin, vitamin D and parathyroid hormone, so a lone odd value is usually rechecked before it means anything |
| Phosphorus | 2.5 – 4.5 mg/dL | Balance | Moves opposite calcium and drifts up late, when filtering has been reduced for a long time |
What does a slightly high creatinine mean?
Usually less than the arrow suggests, and it is worth knowing why. Creatinine is a muscle by-product, so a broad-shouldered adult and a slight one can filter equally well and print different numbers. Add a dehydrated afternoon, a protein shake, a heavy leg day or certain common medicines and a single reading can move without your kidneys changing at all.
That is what eGFR is for. It folds age and sex into the creatinine so two different bodies can be compared on the same scale — an estimate, deliberately, not a measurement. One value slightly out is a prompt to repeat properly hydrated in a few weeks. Two values in the same direction, months apart, is the thing a doctor actually acts on.
Aira and Teresa explain a marker and coach the follow-through on WhatsApp, in plain language. They do not diagnose and do not prescribe. Dr. Manju, MD Pathology, verifies every report.
Why is a urine test added to a kidney panel?
Because blood and urine answer different questions. The blood panel shows what the kidneys failed to clear; urine shows what they are letting slip out. Small amounts of albumin can appear in urine while creatinine is still comfortably normal, which makes the Urine Albumin/Creatinine ratio the earlier of the two signals. It is ₹500, and a Urine Complete Examination is ₹120. Either can be collected in the same visit as the blood sample.
What does a kidney test cost in Kanpur?
The whole price list is published and it is the same at the counter. Your sample is barcoded at the chair, run on calibrated analyzers and reviewed by a pathologist before release, and the lab is registered under the UP Clinical Establishments Act. Routine results are typically ready in about 6 hours.* Home collection is available and charged separately; the fee varies by area, so we quote it when you book.
A kidney panel is a set of numbers that only make sense against each other. In a Smart Report, creatinine is printed beside its eGFR and its previous value, with the comparison already written out in a sentence instead of left as a red arrow for you to interpret at 11 pm.
What should you do next?
Food. Salt is the lever most people underestimate, and most of it is not in the salt shaker — it is in pickle, papad, namkeen, packet masala and bakery bread. Reading one label a week is more durable than a resolution. Protein is worth eating, not fearing; the amount that suits you depends on your own numbers and is a conversation with your doctor, not a rule from a blog.
Movement. The kidneys care most about blood pressure and blood sugar, and walking moves both. Thirty minutes on most days, counted in ten-minute pieces, is the realistic dose. Skip the heavy leg session in the 48 hours before your sample — the creatinine it releases is muscle, not filtering, and it can make a clean report look worse than it is.
Habits. Water steadily across the day rather than a litre before the test. Keep a written list of everything you take, including painkillers and over-the-counter supplements, because regular anti-inflammatory tablets are the most common avoidable strain we see written on a requisition. If you already track blood pressure at home, bring those readings to the appointment — they are the context your creatinine is missing.