Kidney function test (RFT): normal ranges and what they mean

A kidney function test (RFT) usually checks urea, creatinine, eGFR and electrolytes. Typical adult ranges: urea 15 to 45 mg/dL (BUN 7 to 20), creatinine 0.7 to 1.3 mg/dL in men and 0.6 to 1.1 in women, eGFR 90 or above, potassium 3.5 to 5.0 mmol/L. A urine ACR below 30 mg/g completes the check. Your lab prints its own ranges.

Reviewed by the dietitian.pk dietitian team Last reviewed 18 October 2026

What a kidney function test includes

Pakistani labs sell this panel as RFT, KFT, "renal profile" or "urea, creatinine and electrolytes" (U&E). The names differ but the core is the same: two waste products (urea and creatinine), the eGFR calculated from creatinine, and four electrolytes. A blood test alone can miss early damage, so doctors pair it with a urine test. Without both, kidney disease in its early stages, when diet and medicines help most, is easy to miss.

Blood test normal ranges (adults)

Test	Typical adult range	What it tells you
Urea (blood urea)	15 to 45 mg/dL (2.5 to 7.8 mmol/L)	Waste from protein. Rises with dehydration, a high-protein diet, bleeding in the stomach, some medicines and reduced kidney function
BUN (blood urea nitrogen)	7 to 20 mg/dL	The same test reported another way: urea ≈ BUN × 2.14. Check which one your report shows before comparing
Creatinine	Men 0.7 to 1.3 mg/dL; women 0.6 to 1.1 mg/dL	Waste from muscle. Used to calculate eGFR. Details on the creatinine page
eGFR	90 or above (60 to 89 can be normal with age)	Estimated filtering rate in mL/min/1.73 m². Below 60 for over 3 months = chronic kidney disease
BUN : creatinine ratio	About 10:1 to 20:1	A high ratio with normal creatinine often points to dehydration or a high-protein intake rather than kidney damage
Sodium (Na)	135 to 145 mmol/L	Low with vomiting, diarrhoea, some BP tablets or too much plain water; high with dehydration
Potassium (K)	3.5 to 5.0 mmol/L (some labs up to 5.3)	High potassium affects the heart and is the most urgent result on this panel
Chloride (Cl)	96 to 106 mmol/L	Read together with sodium and bicarbonate
Bicarbonate (HCO₃ / CO₂)	22 to 29 mmol/L	Low when weak kidneys cannot clear acid (metabolic acidosis), or with severe diarrhoea

Ranges vary a little between labs and analysers; always compare with the range printed on your own report. Ranges for children and pregnancy are different. For eGFR stages G1 to G5 and what raises creatinine, see creatinine normal range.

Tests often added to the panel

Test	Typical adult range	Why it is checked
Uric acid	Men 3.4 to 7.0 mg/dL; women 2.4 to 6.0 mg/dL	High in gout and often in kidney disease
Calcium	8.5 to 10.2 mg/dL	Can fall in advanced kidney disease
Phosphorus (phosphate)	2.5 to 4.5 mg/dL	Rises in advanced kidney disease and on dialysis; diet and binders control it
Albumin (blood)	3.5 to 5.0 g/dL	Low with heavy protein loss in urine, poor intake or liver disease

For a high uric acid, see the uric acid diet.

Urine tests: the half most people skip

Test	Normal	What an abnormal result means
Urine ACR (albumin : creatinine ratio)	Below 30 mg/g (below 3 mg/mmol)	30 to 300 mg/g = moderately increased (A2); above 300 = severely increased (A3). The earliest sign of kidney damage in diabetes and high BP
Urine routine (urine R/E): protein	Nil or trace	Repeated protein needs an ACR to measure it
Urine R/E: blood (RBCs)	Nil, or 0 to 2 per high-power field	Can come from stones, infection, menstruation or the kidney itself
Urine R/E: pus cells	0 to 5 per high-power field	More, with burning or fever, suggests a urine infection
Urine R/E: sugar	Nil	Usually means blood sugar is high; also seen with some diabetes medicines (SGLT2 inhibitors)

KDIGO stages kidney disease by both eGFR and urine albumin. Someone with a normal eGFR but an ACR of 100 mg/g already has kidney damage, and this is usually the first sign in diabetes. A single high ACR is repeated, because fever, heavy exercise, a urine infection or menstruation can raise it for a day.

Average eGFR by age

Kidney function falls slowly with age. The averages below come from the National Kidney Foundation. A result near the average for your age with a normal urine test is usually not a concern.

Age (years)	Average eGFR (mL/min/1.73 m²)
20 to 29	116
30 to 39	107
40 to 49	99
50 to 59	93
60 to 69	85
70 and above	75

eGFR is calculated with the CKD-EPI 2021 equation from creatinine, age and sex. It is less accurate in bodybuilders, amputees, very thin or bed-bound people and in pregnancy; doctors then use cystatin C or a timed urine collection.

Common result patterns

High urea, normal creatinine: most often dehydration (summer heat, diarrhoea, fasting without enough water at sehri and iftar), a high-protein diet or protein shakes, or steroids. Black stools with a high urea can mean bleeding in the stomach and need a doctor the same day.
High urea and high creatinine, low eGFR: reduced kidney function. One result is not a diagnosis: your doctor repeats it, checks the urine and compares with old reports to decide whether it is sudden (AKI) or long-standing (CKD).
Normal eGFR, high urine ACR: early kidney damage, common in diabetes and high blood pressure. This is the stage where good sugar and BP control can slow or stop the damage.
High potassium: can come from weak kidneys, some BP medicines, salt substitutes or a lot of high-potassium food. A haemolysed (damaged) sample also gives a falsely high reading, so a surprising result is often repeated.
Low sodium: vomiting, diarrhoea, some water tablets, or drinking very large amounts of plain water. Severe low sodium causes confusion and needs hospital care.
Low bicarbonate with low eGFR: the kidneys are not clearing acid. Your doctor may prescribe treatment; more fruit and vegetables can help, but only within your potassium limit.

When a result needs urgent attention

Acute kidney injury is defined by KDIGO as a creatinine rise of 0.3 mg/dL or more within 48 hours, a rise to 1.5 times the usual level within 7 days, or very little urine for 6 hours or more. In Pakistan, common triggers are severe diarrhoea, heatstroke, dengue and other serious infections, and painkillers such as diclofenac taken while dehydrated. AKI often recovers if it is treated early, so do not wait for a routine appointment.

Who should have kidney tests, and how often

Diabetes: eGFR and urine ACR at least once a year (ADA and KDIGO). See the diabetic diet chart.
High blood pressure: at diagnosis and then at least yearly. See the high BP diet.
Heart disease, kidney stones, gout, obesity, or a parent or sibling with kidney disease or on dialysis.
Long-term use of painkillers (diclofenac, ibuprofen, mefenamic acid) or lithium, or regular "kidney tonics" and herbal powders of unknown content.
Known CKD: as often as your nephrologist advises, usually every 3 to 12 months depending on the stage.

Getting an accurate result

Drink your normal amount of water; do not test while dehydrated after a long fast or heavy sweating.
Skip a large meat meal or protein shake the evening before, because cooked meat briefly raises creatinine.
Avoid hard exercise for 24 to 48 hours and stop creatine supplements a week before, if your doctor agrees.
Give the urine sample from the first morning urine for ACR if your lab asks, and not during menstruation.
Tell the doctor about all medicines. Some (for example trimethoprim) raise creatinine without harming the kidneys.
Keep old reports. A trend over months says more than one number.

What to eat when a result is high

Diet is set from the result that is abnormal, never from a general "kidney diet" list. The main points:

Any reduced eGFR or high ACR: salt under 5 g a day (about one level teaspoon in all food), which means fewer achar, nimko, papad and packaged snacks. Blood pressure and sugar control matter more than any single food.
High urea: enough water if you are dehydrated, and no protein powders. Protein is reduced only if your eGFR is low, to an amount your nephrologist and dietitian set, because too little protein causes muscle loss.
High potassium: smaller portions of kela, khajoor, dried fruit, coconut water, aloo and orange juice; leach vegetables by boiling and throwing away the water; never use "low-sodium" salt substitutes, which are mostly potassium.
High phosphorus: cut cola drinks, processed cheese and fast food first, because added phosphate is absorbed almost completely.

Full meal plans are on the kidney patient diet chart (CKD and dialysis) and the kidney stone diet chart. Our renal dietitian consultation plans the diet from your own reports.

See a doctor first if

Potassium is 6.0 mmol/L or above (same day)
Creatinine has risen quickly, or you pass very little urine
eGFR is below 60, or urine ACR is above 30 mg/g
You have swelling, breathlessness, blood in the urine or constant vomiting
You are pregnant, or the report is for a child

Common questions

What is a kidney function test (RFT)?

A kidney function test, also called a renal function test, RFT or KFT, is a group of blood tests that shows how well your kidneys clear waste and balance salts. It usually includes urea or BUN, creatinine with eGFR, and electrolytes (sodium, potassium, chloride, bicarbonate). Many labs add uric acid, calcium and phosphorus. A full kidney check also needs a urine test: urine ACR and a urine routine.

Do I need to fast for a kidney function test?

Usually no. Some labs ask you to fast when the RFT is done together with sugar or cholesterol. For a fair result, avoid a large meat or protein-shake meal the night before, heavy exercise for a day or two, and creatine supplements; drink your normal amount of water and take your usual medicines unless your doctor says otherwise.

What is the normal urea level?

Most Pakistani labs report blood urea, normally about 15 to 45 mg/dL (2.5 to 7.8 mmol/L). Labs that report BUN (blood urea nitrogen) use 7 to 20 mg/dL. They are the same test in different units: urea is about 2.14 times BUN. A raised urea with normal creatinine is often dehydration or a high-protein diet.

What is the normal GFR by age?

Above 90 mL/min/1.73 m² is normal at any age. Average eGFR falls slowly with age: about 116 in your 20s, 99 in your 40s, 85 in your 60s and 75 after 70. An eGFR of 60 to 89 with a normal urine test is often normal ageing, not disease. Below 60 for more than three months is chronic kidney disease at any age.

Is creatinine different by age?

Children have much lower creatinine because they have less muscle, so their labs use age-specific ranges. In adults the range does not change much with age, but the same creatinine means less kidney function in an older or thinner person. That is why eGFR, which includes age and sex, is used instead of creatinine alone.

When should I worry about my kidney test results?

Get same-day medical advice if potassium is 6.0 mmol/L or above, if creatinine has risen quickly (by 0.3 mg/dL or more within two days, or by half again within a week), or if you pass very little urine. See your doctor soon if eGFR is below 60, urine ACR is above 30 mg/g, or results are getting worse on repeat tests.

What are the first signs of kidney problems?

Usually there are none. Early kidney disease is silent, which is why people with diabetes, high blood pressure or a family history should test every year. When symptoms come they include swelling of the feet or around the eyes, foamy urine, passing urine at night, tiredness, itching, poor appetite and nausea.

What is the difference between acute kidney injury and chronic kidney disease?

Acute kidney injury (AKI) is a sudden fall in kidney function over hours or days, often from severe dehydration (diarrhoea, heatstroke), serious infection, or medicines such as painkillers. It needs urgent care and often recovers. Chronic kidney disease (CKD) is damage lasting more than three months, most often from diabetes and high blood pressure, and is managed long term.

Can diet improve kidney function test results?

Diet cannot repair damaged kidneys, and no juice or herbal tonic lowers creatinine. Diet does protect the kidneys you have: less salt, controlled sugar and blood pressure, the right protein for your stage, and limits on potassium or phosphorus when those results are high. Some results, such as a high urea from dehydration, do improve with enough water.

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