Renal Function Test (RFT)

What is a Renal Function Test?

A Renal Function Test (RFT) is a group of blood and urine tests designed to assess kidney function and identify any potential kidney disease. The RFT test report format typically includes measurements of albumin-creatinine ratio, cystatin C, glomerular filtration rate (GFR), and more, which help healthcare practitioners evaluate how well the kidneys filter waste products from the blood. These tests are crucial for diagnosing chronic kidney disease (CKD), chronic renal disease, and acute kidney injury.

By measuring kidney functions, healthcare providers can detect decreased blood flow to the kidneys, which may indicate underlying issues such as urinary tract infections or hypertension. The RFT is particularly significant for patients with chronic renal impairment or those at risk of end-stage renal disease, as it allows for early intervention and management. Regular monitoring through renal function tests is essential for individuals with known kidney issues, providing valuable insights into their health status and guiding treatment plans. Overall, RFT plays a critical role in assessing renal function and ensuring timely care for various kidney-related conditions.

How does the Renal Function Test template work?

Carepatron's free Renal Function Test template makes it easy for healthcare professionals to document their patient's findings. Here's how to use the template:

Step 1: Download the form

Click "Use Template" to utilize the in-app template, allowing you to customize it for your practice's need. Click "Download" for a PDF copy.

Step 2: Record results

Use the Renal Function Test to record your patient's findings for urinalysis, creatine clearance, blood urea nitrogen (BUN) tests, and more. Write any next steps in the "Addional notes" for your patient.

Step 3: Explain to your patient

Based on the results from the Renal Function Test, work with your patient to determine the next steps for their treatment or further testing.

Step 4: Keep accurate records

Store the completed Renal Function Test forms in your patient's health records to maintain an accurate and up-to-date history of their kidney function. This will be helpful in tracking any changes over time and adjusting treatment plans as needed.

What do the results mean?

A renal function test assesses kidney health by evaluating key indicators such as glomerular filtration rate, creatinine, blood urea nitrogen, proteinuria, and more. Here’s an overview of what the results typically reveal (Gounden & Jialal, 2023):

Glomerular filtration rate

The GFR is one of the best indicators of kidney function. A normal GFR for adults ranges from 90 to 120 mL/min/1.73m². Results below this range indicate decreased kidney function, potentially signaling chronic kidney disease.

Serum creatinine

Creatinine is a waste product that the kidneys filter from the blood. Elevated levels of serum creatinine suggest impaired kidney function. A creatinine clearance test calculates GFR, though results may overestimate GFR due to tubular secretion. Low creatinine clearance may signal kidney disease, while elevated levels may indicate severe dehydration or obstruction.

Blood urea nitrogen

BUN measures the amount of nitrogen in the blood that comes from urea, a byproduct of protein metabolism. Elevated BUN levels can indicate reduced kidney function but may also increase due to dehydration, high protein intake, or gastrointestinal bleeding.

Albuminuria and proteinuria

Albuminuria indicates abnormal levels of albumin in the urine, often signifying early kidney damage or diabetic nephropathy. Urine albumin is measured as the albumin-to-creatinine ratio (ACR):

• A1: ACR < 30 mg/g (normal).
• A2: ACR 30-300 mg/g (moderate increase).
• A3: ACR > 300 mg/g (severe increase, indicative of nephrotic syndrome).

Frank proteinuria (exceeding 3.5 g/d) may be a sign of nephrotic syndrome, characterized by protein leakage, edema, and increased cholesterol.

Cystatin C

Cystatin C is a protein used as an alternative marker for GFR. Unlike creatinine, it is not affected by muscle mass or diet. Elevated levels of cystatin C reflect reduced GFR and worsening kidney function. It is particularly useful in early-stage kidney disease when creatinine levels may still appear normal.

Urinalysis

Urine analysis results provide additional insights:

• Color and clarity: Darker urine may indicate dehydration, and cloudy urine may suggest infection.
• Protein: Normally absent in urine, its presence indicates glomerular damage.
• Blood: May indicate infection or injury.
• Crystals: Specific types (e.g., uric acid, calcium oxalate) may signal gout or kidney stones.

What problems does a Renal Function Test detect?

Renal Function Tests play a vital role in identifying various kidney-related issues. Here are some of the key problems that these tests can detect:

Chronic kidney disease

RFT helps assess kidney functions, allowing for the early detection of chronic kidney disease (CKD). By monitoring key markers such as urine albumin, elevated creatinine levels, and the creatinine ratio, healthcare practitioners can evaluate kidney health and track any deterioration over time. Identifying CKD early enables timely interventions, including lifestyle changes or renal replacement therapy, to slow disease progression.

Glomerular dysfunction

RFTs are crucial for detecting glomerular dysfunction, which refers to problems in the filtering units of the kidneys. Abnormal results in urine tests, such as elevated levels of uric acid and protein, can indicate issues with glomerular filtration. Understanding these changes can help healthcare providers determine appropriate treatments and monitor the effectiveness of interventions.

Hypertension and its impact on kidney health

High blood pressure is a significant risk factor for kidney damage. Regular kidney function tests allow healthcare professionals to assess kidney functions in patients with high blood pressure. A comprehensive RFT test can reveal how well the kidneys are managing blood pressure levels and identify any signs of stress or damage to healthy kidneys.

Increased endothelial permeability

Certain RFT results may indicate increased endothelial permeability, which can lead to various kidney problems. By identifying these changes through blood tests and urine tests, healthcare providers can implement strategies to manage or prevent further complications, ensuring optimal kidney health.

Reference

Gounden, V., & Jialal, I. (2023). Renal function tests. National Library of Medicine; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK507821/