RFT / Renal Function Test Explained
If your doctor has written RFT on a laboratory request, you may expect it to mean a standard set of kidney tests.
However, in practice, RFT does not always mean exactly the same group of tests in every laboratory or clinical setting.
RFT usually stands for:
Renal Function Test or Renal Function Tests
The term generally refers to blood tests used to provide information related to kidney function.
But the important question is:
Some RFT requests may contain only a small number of tests such as blood urea and serum creatinine.
Other laboratories or doctors may include additional tests.
Therefore, always check the actual investigation request or laboratory report rather than relying on the abbreviation alone.
Why Can “RFT” Mean Different Things?
The abbreviation RFT is widely used, but different laboratories and healthcare settings may use it for different combinations of kidney-related blood tests.
For example, one laboratory may use RFT for:
- blood urea;
- serum creatinine.
Another may add:
- uric acid.
A broader kidney-related profile may include additional tests such as:
- electrolytes;
- calcium;
- phosphate;
- other measurements.
This is why the term RFT alone does not always tell you exactly which tests will be performed.
If Your Request Just Says “RFT”
Before giving the sample, check one of the following:
- Are the individual tests written on the request?
- Does the laboratory have a defined RFT package?
- Does the laboratory distinguish between RFT and Renal Profile?
- If the meaning is still unclear, ask the laboratory or the doctor who requested the test.
What Tests May Be Included in an RFT?
The exact tests can vary.
However, the tests most commonly associated with an RFT request include:
Blood Urea / BUN
A blood measurement related to urea, a waste product removed partly through the kidneys.
Serum Creatinine
A blood measurement commonly used when assessing kidney filtration.
eGFR
An estimate of kidney filtration that may be reported with the serum creatinine result.
Some RFT packages may also include other tests such as:
- uric acid;
- serum electrolytes;
- additional measurements depending on the laboratory.
Always check your own request or report.
Is eGFR Part of the RFT?
You may see eGFR on your report when serum creatinine has been tested.
eGFR stands for estimated glomerular filtration rate.
It is generally a calculated estimate rather than another substance independently measured in the blood.
Therefore, a laboratory may report Serum Creatinine + eGFR even if the request mainly specified creatinine or RFT.
For a detailed explanation, read eGFR Explained.
Blood Urea / BUN
Blood urea is one of the tests commonly associated with an RFT request.
Urea is a waste product formed mainly when the body handles protein and nitrogen-containing waste.
The kidneys remove much of it from the blood.
Some laboratory reports use Urea, while others may use BUN — Blood Urea Nitrogen.
These are closely related measurements but are not numerically identical.
A high blood urea or BUN result does not automatically mean kidney failure because the value can also be affected by factors such as hydration and other medical conditions.
For the complete explanation, read Blood Urea / BUN Test Explained.
Serum Creatinine
Serum creatinine is another test commonly included when doctors request kidney-related blood tests.
Creatinine is a waste product produced mainly from normal processes involving muscles.
The kidneys remove it from the blood.
A rise in serum creatinine can occur when kidney filtration decreases, but the result must be interpreted according to the individual patient and other findings.
A high creatinine result does not automatically mean kidney failure.
For the complete explanation, read Serum Creatinine Test Explained.
Also see High Creatinine & eGFR Explained.
Uric Acid
Some laboratories may include uric acid in an RFT package, while others do not.
Uric acid is a waste product that is partly removed from the body through the kidneys.
However:
A high uric acid result can occur for several different reasons.
Are Electrolytes Included in RFT?
Sometimes.
Some doctors or laboratories may include serum electrolytes when requesting or providing a broader kidney-related blood-test package.
Common electrolytes include:
- sodium;
- potassium;
- chloride.
However, electrolytes should not be assumed to be included in every RFT.
If your request simply says RFT and you need to know whether electrolytes are included, check the laboratory's package or ask the healthcare professional who requested the test.
For electrolyte results, use the existing Electrolyte Result Interpreter.
RFT and Renal Profile Are Not Always the Same
The terms RFT and Renal Profile are sometimes used in similar ways, but they should not automatically be assumed to mean exactly the same laboratory package.
An RFT request may refer to a relatively small group of kidney-related tests.
A Renal Profile / Kidney Profile may refer to a broader laboratory package containing:
- creatinine;
- eGFR;
- blood urea/BUN;
- electrolytes;
and, in some laboratories:
- calcium;
- phosphate/phosphorus;
- uric acid;
- other tests.
RFT vs Renal Profile
| RFT | Renal Profile |
|---|---|
| Meaning can vary. May sometimes be Blood Urea, Serum Creatinine, ± other tests. | Usually describes a broader laboratory package. May include Creatinine, eGFR, Urea/BUN, Electrolytes, ± Calcium, ± Phosphate, ± Uric Acid. |
Are Urine Tests Such as ACR and UFR Part of an RFT?
Not automatically.
Urine ACR and UFR / urinalysis are urine tests.
They can provide important kidney-related information, but they are separate investigations and should not automatically be assumed to be included simply because a request says RFT.
If the doctor wants urine testing, it may be written separately or requested as part of a broader assessment.
For more information, read Urine Albumin and ACR Test Explained and Urine Full Report (UFR) / Urinalysis Explained.
Do I Need to Give a Urine Sample for an RFT?
Usually, the common blood tests associated with an RFT are performed from a blood sample.
A urine sample is needed only if urine investigations have also been requested.
Examples include:
- UFR / urinalysis;
- urine ACR;
- urine culture;
- other specific urine tests.
If your request is unclear, check whether a urine investigation is listed separately.
How Is an RFT Done?
The common blood tests associated with an RFT are performed using a blood sample.
A healthcare worker usually takes a small amount of blood from a vein in your arm.
The laboratory then performs the individual tests included in its RFT package or specifically written on the request.
Because RFT packages can vary, two patients who were both told to have an “RFT” may not necessarily have exactly the same set of tests performed.
Do I Need to Fast for an RFT?
Fasting is not always required specifically for the common blood tests associated with an RFT.
However, RFT may be performed together with other investigations that require fasting or special preparation.
Therefore:
If you are unsure, ask the laboratory or the healthcare professional who requested the tests.
Should I Drink Extra Water Before an RFT?
Do not deliberately drink unusually large amounts of water simply to try to make the test results look better.
Unless you have been given specific instructions, follow your usual fluid intake and the laboratory preparation advice.
Dehydration can affect some kidney-related blood results, but excessive water intake before testing is not a reliable way to produce a “normal” RFT.
Some patients also have medical conditions that require specific fluid advice.
Should I Stop Medicines Before an RFT?
Do not stop prescribed medicines simply because you are having an RFT unless the healthcare professional responsible for your care has specifically told you to do so.
Some medicines can affect kidney-related blood results or electrolytes.
In some situations, checking the effect of a medicine may actually be one reason the RFT was requested.
If you are unsure, ask the doctor or healthcare professional who requested the investigation.
How to Read an RFT Report
Start by identifying the individual tests actually listed on the report.
Do not interpret the heading RFT as though it were one single numerical result.
Your report may contain:
- Blood Urea / BUN
- Serum Creatinine
- eGFR
- Uric Acid
- Electrolytes
- other measurements
depending on what was ordered and what the laboratory includes.
For each test, check:
- Test name
- Result
- Unit
- Reference range
Then use the dedicated article or report-reader tool for the individual result.
What Is the Normal RFT Range?
There is no single normal RFT value because RFT is not one measurement.
Each individual laboratory test has its own result, unit and reference range.
Use the reference interval printed beside the individual result on your own laboratory report.
Do not compare creatinine, urea, eGFR, uric acid, or electrolytes as though they share the same normal range.
What If One Result on My RFT Is Abnormal?
One abnormal result does not automatically mean that you have kidney failure.
Different tests are affected by different factors.
For example:
- creatinine and eGFR provide related information about kidney filtration;
- blood urea can also change with hydration and other factors;
- uric acid can be abnormal for several different reasons;
- electrolyte abnormalities can occur because of many medical conditions and medicines.
The abnormal result should therefore be interpreted individually and together with the rest of the report.
Does a Normal Creatinine Mean the Whole RFT Is Normal?
Not necessarily.
An RFT may contain more than one result.
Even if serum creatinine is within the laboratory reference range, another result may be abnormal.
Also, the interpretation of kidney-related blood tests depends on factors such as eGFR, previous results and the patient's medical situation.
Always look at the complete report rather than only one number.
Can Urea Be High When Creatinine Is Normal?
Yes.
Blood urea and creatinine are affected by different factors and do not always change together.
For example, blood urea can rise with dehydration and other conditions even when creatinine does not show the same change.
This pattern should be interpreted according to the patient's overall situation.
For more detail, use Blood Urea / BUN Test Explained.
What If Creatinine Is High?
A high creatinine result can occur when kidney filtration is reduced, but a single elevated creatinine result does not automatically establish the cause or mean that a patient has kidney failure.
Doctors often consider:
- eGFR;
- previous creatinine results;
- current illness;
- hydration;
- medicines;
- other blood and urine tests.
For more information, read High Creatinine & eGFR Explained.
Need Help Understanding the Results?
Use the relevant tool for the results actually shown on your report.
Kidney Function Report Reader
Use for supported results such as serum creatinine, eGFR and urine ACR: open the Kidney Function Report Reader.
Electrolyte Result Interpreter
Use for supported electrolyte results: open the Electrolyte Result Interpreter.
Need to Calculate eGFR?
Use the appropriate calculator: Adult eGFR Calculator or Pediatric eGFR Calculator. Adult and pediatric eGFR calculations are not necessarily the same.
If Your Doctor Writes “RFT” — What Should You Do?
- Step 1 — Look for individual tests written beside RFT.
- Step 2 — If none are written, ask the laboratory what its RFT package includes.
- Step 3 — Check whether the laboratory distinguishes between RFT and Renal Profile.
- Step 4 — If the intended tests are still unclear, clarify with the requesting doctor or healthcare service.
- Step 5 — After testing, read the individual results rather than looking for one overall RFT number.
- Step 6 — Use the relevant dedicated article or report-reader tool for results you want to understand.
What If the Laboratory Asks Whether You Need RFT or a Renal Profile?
Do not choose between the two simply by guessing.
Check the investigation request.
If the doctor has listed individual tests, follow those tests.
If the request only says RFT and the laboratory offers more than one kidney-related package, ask the laboratory what its RFT contains.
If there is still uncertainty about what the doctor intended, clarify with the requesting doctor or healthcare service.
The goal is to perform the tests that were actually intended — not simply choose the package with the most tests.
If the Doctor Wrote Only “Creatinine,” Do I Need a Full RFT?
Not automatically.
If the request specifically asks for serum creatinine, the doctor may only need that test.
Do not automatically add a larger laboratory package unless it was requested or appropriately recommended.
Similarly, if the request specifies blood urea, serum electrolytes, ACR, or UFR, the requested test should not automatically be replaced by an RFT package.
When Should I Discuss My RFT Results With a Doctor?
Discuss the results with the healthcare professional who requested them if:
- you were specifically asked to return with the report;
- one or more results are significantly abnormal;
- abnormalities persist on repeat testing;
- there has been an important change from previous results;
- you have a known kidney or other medical condition;
- you are taking medicines that require kidney or electrolyte monitoring;
- you are unsure why the tests were requested.
The importance of a result depends on the individual test and medical situation, not simply on whether the report marks it H or L.
When May Prompt Medical Attention Be Needed?
Seek prompt medical attention if you are unwell and develop symptoms such as:
- markedly reduced urine output;
- difficulty passing urine;
- repeated vomiting or inability to keep fluids down;
- significant swelling;
- unusual drowsiness or confusion;
- difficulty breathing;
- severe weakness;
- palpitations or an abnormal heartbeat sensation;
- a rapidly worsening general condition.
Remember
In Sri Lanka, different laboratories and healthcare settings may use RFT for different combinations of tests.
Commonly associated tests include blood urea, serum creatinine, and eGFR when reported with creatinine — and some packages may include additional tests. A broader Renal Profile may contain more measurements. Always check the individual tests actually ordered and reported.
Related kidney health topics
Key Points
- RFT stands for Renal Function Test or Renal Function Tests.
- RFT does not have one completely standardized composition.
- Some Sri Lankan settings use RFT for blood urea and serum creatinine.
- Other RFT packages may contain additional tests such as uric acid.
- Electrolytes may be included in broader kidney-related testing but should not automatically be assumed to be part of every RFT.
- eGFR may be reported with serum creatinine.
- RFT and Renal Profile may overlap but are not necessarily identical packages.
- ACR and UFR are urine tests and are not automatically included simply because RFT was requested.
- Fasting is not always required specifically for the common RFT blood tests.
- Do not deliberately over-hydrate or stop prescribed medicines simply because an RFT is being performed.
- An RFT does not have one overall numerical result or one normal range.
- Read each individual result separately.
- If the request is unclear, check what the laboratory's RFT contains or clarify with the requesting healthcare professional.