What Do Kidney Function Tests Mean in a Check-Up?

check-up During treatment, kidney functions are usually evaluated with blood and urine tests. Blood values ​​such as creatinine, estimated glomerular filtration rate (eGFR), urea or BUN can provide information about the filtering function of the kidneys. Evaluation of albumin or protein in urine can help look for early signs of kidney damage.

However, chronic kidney disease cannot be diagnosed by looking at a single creatinine or eGFR result. The results need to be evaluated together with the person's age, muscle mass, fluid status, medications used, diseases such as diabetes and hypertension, and previous tests.

There may be no obvious complaints in the early stages of kidney diseases. For this reason, it may be important to evaluate kidney functions during check-up, especially in people with risk factors for diabetes, high blood pressure, cardiovascular disease or kidney disease.

Which Kidney Tests Are Checked During Check-Up?

The contents of check-up packages may differ from each other. While basic packages may include blood tests such as creatinine and urea, urine albumin/creatinine ratio or more detailed kidney tests may not be included in every package.

Commonly evaluated tests may include:

• Serum creatinine

• eGFR

• Urea or BUN

• Complete urinalysis

• protein in urine

• Urine albumin/creatinine ratio

• Electrolytes such as sodium and potassium

Which tests are needed depends on the person's health condition.

What is Creatinine?

Creatinine is a waste product produced during the normal functioning of muscles. Creatinine in the bloodstream is filtered by the kidneys and removed from the body.

When the filtering capacity of the kidneys decreases, blood creatinine levels may increase. For this reason, creatinine is one of the most frequently used laboratory values ​​in evaluating kidney functions.

What Does High Creatinine Mean?

High creatinine may suggest that there may be a decrease in kidney function, but it does not by itself make a definitive diagnosis of kidney disease.

Creatinine value:

• muscle mass

• Age

• Nutrition

• intense exercise

• fluid loss

• some medications

• acute diseases

may affect.

Therefore, the result should be evaluated especially in conjunction with eGFR and other kidney tests.

Does low creatinine indicate that the kidneys are working very well?

Not always. Since creatinine production is related to muscle tissue, creatinine value may be lower in people with low muscle mass.

In cases of advanced age, low muscle mass or some chronic diseases, looking only at the creatinine level may make kidney function look better than it is. Therefore, different evaluation methods can be used when necessary.

What is eGFR?

eGFR is a value used to estimate how well the kidneys filter blood. It is usually calculated using information such as serum creatinine result and age.

eGFR value may provide a more meaningful general indicator than creatinine value in the evaluation of kidney functions.

In general, eGFR of 60 mL/min/1.73 m² and above may be consistent with adequate renal filtration capacity in most adults. However, the result should not be interpreted alone.

If eGFR is below 60, is there kidney disease?

A single eGFR value below 60 is not sufficient for the diagnosis of chronic kidney disease.

In chronic kidney disease, it must be shown that the impairment of kidney function or kidney damage usually persists for at least three months.

Temporary dehydration, acute illness or some medications may affect the eGFR value. Additionally, eGFR may naturally decrease with age.

When a low result is detected, the physician may request a repeat of the test and urine albumin evaluation.

What Do Urea and BUN Mean?

Urea is one of the waste products formed during the breakdown of proteins in the body. The kidneys remove urea from the bloodstream and excrete it in urine.

In some laboratories, urea may be reported directly, while in others, BUN, which means blood urea nitrogen, may be reported.

High urea or BUN:

• kidney dysfunction

• fluid loss

• High protein intake

• some medications

• Gastrointestinal bleeding

It may be associated with different situations such as:

Therefore, high urea level alone does not mean that there is kidney failure.

Why is Albumin in Urine Important?

Albumin is an important protein normally found in the blood. Healthy kidneys prevent most of the albumin from passing into the urine.

When the filter structure of the kidneys is damaged, the amount of albumin in the urine may increase. This may be especially important in the early stages of kidney damage due to diabetes and hypertension.

What is the Urine Albumin/Creatinine Ratio?

Urine albumin/creatinine ratio, or uACR for short, evaluates the amount of albumin in the urine according to the creatinine value.

In general, a uACR value below 30 mg/g is considered normal or compatible with a mild level. Higher values ​​may suggest kidney damage.

However, intense exercise, fever, infection and some temporary conditions may cause an increase in albumin in the urine. Therefore, a high result may need to be retested.

Does Normal Creatinine Show That the Kidneys Are Definitely Healthy?

No. Even if creatinine is within the normal reference range, some people may have kidney disease.

Especially in the early stages of kidney damage, while eGFR is still within normal limits, an increase in albumin in the urine may be observed.

Therefore, not only creatinine should be used to evaluate kidney health:

• eGFR

• Urine albumin/creatinine ratio

• Complete urinalysis

• blood pressure

• diabetes status

• Previous results

can be considered together.

For Whom Are Kidney Function Tests More Important?

Since kidney diseases can progress silently in the early stages, regular evaluation may be more important in some risk groups.

Those with Diabetes

Diabetes is one of the important causes of kidney disease. Blood sugar that remains high for a long time can damage the small vessels of the kidneys.

Therefore, it may be important to evaluate not only creatinine but also eGFR and urine albumin/creatinine ratio in people with diabetes.

Those with Hypertension

High blood pressure can both damage the kidneys and occur as a result of kidney disease.

Evaluation of kidney function and urinary albumin in people with hypertension is one of the important parts of general health monitoring.

Those with a Family History of Kidney Disease

Risk assessment of people with a family history of chronic kidney disease or hereditary kidney disease can be done in more detail.

Family history alone does not mean that a person will develop kidney disease, but it should be reported to the physician when scheduling a check-up.

What to do if kidney tests are high?

If creatinine or urea is high, eGFR is low, or albumin is detected in the urine during check-up, a decision should not be made based on a single result.

If the physician deems it necessary:

• He/she may request the test again.

• Can evaluate urine albumin/creatinine ratio.

• It can control electrolytes.

• It can evaluate blood pressure and blood sugar.

• He or she may request a kidney ultrasound.

• Can review the medications used.

• May recommend nephrology evaluation.

In particular, there is a significant difference between a new result and one that has been ongoing for a long time.

Do You Have to Be Fasting for Kidney Function Tests?

Fasting is not always required for creatinine and eGFR measurement. However, since blood sugar, triglyceride or other tests may be performed at the same time in check-up packages, fasting may be requested before the package.

Before the test, the preparation instructions given by the health institution should be followed.

Intense exercise, excessive meat consumption, or significant dehydration can affect creatinine results in some people. Not deviating from the normal daily routine before the test usually helps to obtain healthier results.

What Can Be Done to Protect Kidney Health?

Blood pressure and blood sugar control are especially important in maintaining kidney health.

In general:

• monitoring blood pressure

• Maintaining blood sugar control if you have diabetes

• Avoiding unnecessary painkiller use

• Consuming enough fluids

• not smoking

• Maintaining a healthy body weight

• Reporting the medications used to the physician

• Not skipping regular health checks

It may help maintain kidney health.

Uncontrolled use of herbal products or supplements to “cleanse the kidneys” is not recommended.

For Which Symptoms Should You Not Wait for a Check-Up Appointment?

Chronic kidney disease may not cause symptoms in the early stages. However, some findings may require more rapid health assessment.

In the following cases, you should consult a healthcare institution instead of waiting for a check-up appointment:

• Significant decrease in the amount of urine

• Inability to urinate at all

• Significant blood in the urine

• rapidly increasing leg or facial swelling

• Severe shortness of breath

• change of consciousness

• Constant vomiting and inability to drink fluids

• Severe side or lower back pain

• Urinary tract symptoms with fever

• Rapidly deteriorating general health condition

In case of inability to urinate at all, severe shortness of breath, change of consciousness or rapidly deteriorating general condition, check-up or online consultation should not be waited and emergency health services should be sought.

This content is for general information purposes. Interpretation of kidney function tests should be made in conjunction with the person's age, health history, medications, and previous laboratory results.

How to Choose a Check-Up Package Including Kidney Tests?

The presence of the phrase "kidney functions" in the check-up package may not mean that all detailed kidney tests have been performed.

The package content specifically includes:

• creatinine

• eGFR

• Urea or BUN

• Complete urinalysis

• sodium and potassium

It can be checked whether tests such as these are available.

A urine albumin/creatinine ratio may also be needed in people at high risk for diabetes, hypertension, or kidney disease. Since this test may not be included in every standard package, the package scope should be examined before purchasing.

Plan Your Check-Up Process with Happ Health

Creatinine, eGFR and urine tests can provide important information in assessing kidney health during check-up. However, a single laboratory result being low or high does not necessarily mean a diagnosis of chronic kidney disease. It is important to interpret the results together with previous values, blood pressure, blood sugar, medications used and other health risks of the person.

Different services offered by Medical Park and Liv Hospital via Happ Health check-up packages You can review, compare whether kidney function tests are included in the package and plan the health assessment process that suits your needs. If you have additional risk for diabetes, hypertension, or kidney disease, you can evaluate with your healthcare professional whether targeted testing such as urine albumin/creatinine ratio is necessary.

With the approach of "Health Everywhere, For Everyone, Always", we attach importance to the importance of early evaluation in kidney diseases and that check-up results should be interpreted not only by looking at laboratory reference ranges, but also by taking into account the whole health status of the person. If a significant disorder is detected in the results, referral may be made to the relevant branch evaluation.

If there is a serious decrease in the amount of urine, inability to urinate at all, significant shortness of breath, change in consciousness or a rapidly deteriorating general condition, a check-up appointment should not be waited and an urgent health evaluation should be obtained.