The medical acronym RFT is frequently encountered by patients and healthcare providers, but it does not refer to a single, standardized test. Its meaning depends entirely on the clinical context. RFT is most commonly interpreted as a measure of organ function, referring to two completely different organ systems. This information clarifies the two primary interpretations of RFT, along with other specialized meanings, to help patients understand their medical records and lab orders.
Renal Function Tests and What They Measure
Renal Function Tests (RFTs) are a collection of blood and sometimes urine analyses designed to assess how well the kidneys filter the blood. The kidneys remove waste products, regulate fluid balance, and maintain electrolyte levels. These tests are routinely ordered to screen for, diagnose, and monitor conditions like kidney disease, diabetes, and high blood pressure.
The RFT panel typically measures the concentration of specific waste products in the blood. One key marker is creatinine, a waste product of normal muscle breakdown that is almost entirely removed from the blood by the kidneys. Elevated serum creatinine levels often signal a decrease in the kidney’s filtration efficiency.
Another important measure is Blood Urea Nitrogen (BUN), which assesses the nitrogen content of urea, a waste product of protein metabolism. High BUN can indicate impaired kidney function, but it is also influenced by factors like dehydration or a high-protein diet. The estimated Glomerular Filtration Rate (eGFR) is a calculated value, derived from serum creatinine, age, sex, and race, that provides the most accurate picture of how quickly the kidneys clear waste.
The RFT also includes measurements of electrolytes, such as sodium, potassium, and chloride, to check the kidney’s ability to maintain balance. An imbalance, particularly high potassium, can lead to serious health issues, including heart rhythm disturbances. A urine component may also look for albumin, a protein that should not be present in urine, as its presence can be an early sign of kidney damage.
Respiratory Function Testing Procedures
Respiratory Function Testing (RFT) is the other major interpretation of the acronym, often used interchangeably with Pulmonary Function Testing (PFT). These tests measure how well the lungs move air and how efficiently oxygen transfers into the bloodstream. They are used to diagnose and monitor lung diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis.
The primary procedure in this RFT is spirometry, a non-invasive test where the patient breathes into a mouthpiece connected to a spirometer. The patient takes a deep breath and then exhales as hard and fast as possible, for as long as possible. This maneuver is performed multiple times to ensure the results are accurate.
Two main values are derived from spirometry: the Forced Vital Capacity (FVC) and the Forced Expiratory Volume in one second (\(\text{FEV}_1\)). The FVC represents the total amount of air the patient can exhale after a maximal inhalation. The \(\text{FEV}_1\) is the volume of air expelled in that first second of the forceful breath.
The ratio of \(\text{FEV}_1\) to FVC is a diagnostic tool used to distinguish between obstructive and restrictive lung diseases. A low \(\text{FEV}_1/\text{FVC}\) ratio indicates an obstructive pattern, where narrowed airways prevent air from being quickly expelled, as seen in COPD. A low FVC with a normal ratio suggests a restrictive pattern, where the lung tissue is stiff or chest wall movement is limited.
Context-Specific RFT Definitions
Beyond the two major organ function assessments, RFT can occasionally refer to other specialized procedures or treatments. One such interpretation is Fibrinolysis Therapy, sometimes called Rapid Fibrinolysis Therapy in cardiology. This treatment involves administering medications to quickly dissolve dangerous blood clots that have formed in the circulatory system, such as during a heart attack or stroke.
This therapy uses drugs to activate the body’s natural clot-busting system, restoring blood flow to prevent tissue death. Another niche interpretation in gastroenterology is Rectal Function Testing. This is a collection of tests used to evaluate the function of the muscles and nerves in the rectum and anus, typically ordered for patients experiencing chronic constipation or fecal incontinence.
The ambiguity of the RFT acronym is why many healthcare institutions now favor writing out the full term, such as “Renal Panel” or “Pulmonary Function Test,” to prevent miscommunication. When encountering RFT, context from the ordering physician or the medical specialty involved is necessary to understand the exact test being referenced.