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Renal Function Testing and Diagnostic Methods

One of the functions of the kidneys is detoxification, where they recycle useful substances and eliminate toxins, uric acid, and nitrogenous waste through the production of urine. When renal function weakens, the body is unable to eliminate excess fluids and waste, eventually leading to kidney failure. But what exactly is renal function? What does the level of renal function indicate? How much does renal function testing cost at different healthcare institutions? The Bowtie team has gathered relevant information on renal function to provide a detailed understanding of renal function testing. Let's explore the details of renal function testing together! When should you consider getting tested?
Author Bowtie Team
Date 2023-07-12
Updated on 2023-09-12
When should you consider getting tested?Who is at higher risk and should consider testing?Kidney function self-assessmentMethods of kidney function testing and common diagnostic indicatorsCost of Renal Function Tests:FAQ

When should you consider getting tested?

If any of the following symptoms occur, it could be a warning sign of kidney problems. It is important to seek medical attention immediately and undergo a series of detailed tests to identify the underlying cause.

  • Burning sensation during urination
  • Increased frequency of urination
  • Presence of blood in the urine
  • Swelling in the lower extremities
  • Swelling around the eyes and face, accompanied by back pain
  • High blood pressure

Who is at higher risk and should consider testing?

If you have any of the following factors, it may increase your risk of developing chronic kidney disease. It is advisable to consult a doctor and undergo regular testing:

  • Advanced age (40 years or older)
  • Long-term smoking
  • Family history of kidney disease
  • Structural abnormalities of the kidneys
  • Regular exposure to cadmium, trichloroethylene, asbestos, or petroleum due to occupational reasons
  • Obesity (BMI > 30)
  • Regular use of medications that may harm the kidneys
  • Diabetes
  • High blood pressure
  • Heart (cardiovascular) disease
  • Regular use of over-the-counter or pain medications
  • African-American, Native American, or Asian-American ethnicity

Kidney function self-assessment

If you suspect kidney problems, you can self-assess whether you have the following symptoms:

Self-assessment methodSymptoms
Do you have swelling?
  • Pay attention if you have swelling within two weeks after catching a cold
  • Wrinkles on the face disappear
  • Depression of subcutaneous tissue (pressing the part of the lower leg bone with a finger, it takes a while to recover!)
Are there any abnormal urine characteristics?
  • Frequent urination
  • Decreased urination
  • Nocturia (excessive urination at night)
  • Polyuria (excessive urination)
  • Abnormal urine color
  • Presence of blood in the urine
Do you experience back or loin pain?
  • Pain in the back, loin, or lower abdomen
  • Heaviness in the waist
Do you experience fatigue or headaches?
  • Fatigue
  • Headaches
  • General weakness
Does your complexion look unhealthy?
  • Pale complexion
  • Darkening of the forehead
  • Darkening of the skin
Do you have difficulty seeing nearby objects?
  • Visual impairment
  • Difficulty reading

However, self-assessment may not be accurate. If you suspect kidney function problems, it is important to seek professional advice from a doctor.

Methods of kidney function testing and common diagnostic indicators

Early-stage chronic kidney disease may not present any symptoms, and problems can only be detected through testing. The following are 6 key indicators used to measure kidney function:

IndicatorTestNormal Range
CreatinineCreatinine is a waste product produced by muscles. Doctors compare the level of creatinine in a urine sample to that in the blood to assess how much waste the kidneys are filtering outFemale:Below 1.2

Male:Below 1.4

Blood Urea Nitrogen (BUN)Urea nitrogen is a waste product in the body that is produced as proteins break down. An elevated level indicates that the kidneys are not effectively filtering out these waste products7 – 20 mg
Glomerular Filtration Rate (GFR)The rate at which blood is filtered by the kidneys. Higher than 60
Urinary ProteinExcessive excretion of albumin in the urine indicates abnormal kidney function90-120ml/min
Urinalysis AnalysisAnalysis of urine sediments, including blood, pus, bacteria, glucose, and protein. Normal sediment should not be present. The presence of sediment indicates possible kidney or bladder infection, kidney disease, kidney stones, or diabetes.Normal sediment should not be present. The presence of sediment indicates possible kidney or bladder infection, kidney disease, kidney stones, or diabetes.
Blood PressureMeasurement of the pressure exerted on the blood vessels during heart function.<140/90 mmHg

In addition to these indicators, doctors may perform other tests to accurately assess a patient’s kidney function. The following are common diagnostic procedures:

Blood Test


Assess the overall health condition of a patient by extracting blood samples. This test ensures the safety of patients with renal cancer, as it helps evaluate their anemia levels and reduces the risk associated with various treatments.


The main parameters examined in a blood test are urea nitrogen and creatinine (normal range: 0.7~1.4 mg/dl). Higher values indicate poorer kidney function.

Suitable Individuals or Cases:

Not recommended for individuals who have recently undergone physical therapy.



Extract urine samples from patients and send them to the laboratory for analysis.


The goal is to detect the presence of “proteinuria.” In healthy adults, the daily protein excretion in urine should be ≤150 mg.

Renal Ultrasound Scan


Uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs.


The aim is to detect structural issues in the kidneys, measure kidney size, identify kidney stones or tumors, and assess for enlargement or shrinkage of the kidneys.

Intravenous Pyelography :


An X-ray examination of the urinary tract that involves injecting a contrast agent to visualize the kidneys, bladder, and the tubes (ureters) that transport urine from the kidneys to the bladder.


Used to diagnose potential urinary tract conditions such as kidney stones, bladder stones, enlarged prostate, renal cysts, or urinary tract tumors.

Suitable Individuals or Cases:

Some individuals may experience side effects from the injection of X-ray contrast agents. Pregnant women should inform their doctors about their pregnancy.

Renal Biopsy


An invasive procedure where a needle is inserted into the kidney to extract a small tissue sample.


Assists in disease diagnosis, guides medication treatment, and determines prognosis. Helps understand the severity of kidney disease.

Suitable Individuals or Cases:

When the aforementioned imaging tests are not clear enough for surgery, doctors may consider a biopsy for live tissue examination.

Cost of Renal Function Tests:

The following table lists the prices of common renal function tests at four private hospitals. The diagnostic services provided by each hospital may not be identical. Factors such as room type, inclusion of contrast agents, etc., can also affect the prices. For accurate and detailed pricing, it is recommended to directly inquire with the hospitals.

Private HospitalExamination ItemFees
Hong Kong Sanatorium & HospitalUnion Hospital Renal Function Test (urea/creatinine/sodium/potassium/chloride/bicarbonate)HK$140 起 (per examination item)
UrinalysisStarting from HK$190
Ultrasound Scan (Kidneys and Bladder)Starting from HK$3,820
CystoscopyStarting from HK$23,067
Gleneagles Hong Kong HospitalRenal Function TestStarting from HK$640
UrinalysisStarting from HK$160
Ultrasound Scan (Kidneys and Bladder)Starting from HK$1,590
Voiding CystourethrogramStarting from HK$4,410
Cystoscopy +/- BiopsyStarting from HK$21,133
Saint Teresa’s HospitalRenal Function (urea, creatinine, total protein, albumin, albumin-to-globulin ratio, sodium, potassium, chloride, bicarbonate)Starting from HK$630
UrinalysisStarting from $155
Cystoscopy Starting from HK$2,700
Ultrasound Scan (Kidneys) Starting from HK$1,000
Hong Kong Baptist HospitalBlood TestStarting from HK$420
UrinalysisStarting from HK$180
Ultrasound Scan (Kidneys)Starting from HK$1,040
  • NoteThe above price information is for reference only (updated as of February 3, 2023).


What is the kidney function index?

Kidney function can be reflected by the levels of creatinine and urea in the blood. Elevated levels indicate a decline in the function of both kidneys. If serum creatinine reaches 140 umol/L (1.6 mg/dl), it means the kidney function has declined by 50%.

How can I determine if I have chronic kidney disease from the kidney function index?

Chronic kidney failure can be divided into the following four stages. When kidney function falls below 25% of normal, uremia appears, leading to kidney failure.

Renal Insufficiency 51% – 80% of normal renal function
Renal Impairment25% – 50% of normal renal function
Renal Failure15% – 25% of normal renal function
Late-stage Renal Failure10-15% of normal renal function
Can these tests be performed together?

Since the symptoms of kidney disease and renal failure are not apparent, multiple tests are often required for a clear diagnosis of kidney function. Therefore, the aforementioned tests can be performed together, and conducting different tests can help doctors identify signs of kidney dysfunction.


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