Kidney function is crucial to overall health. The kidneys are responsible for filtering waste products from the blood, regulating blood pressure, balancing electrolytes, and producing urine. Measuring kidney function is an important aspect of medical evaluations. Below we discuss what normal kidney function values are, how they are measured, and what it means for your health.
What is Kidney Function?
Kidney function refers to how well the kidneys are able to perform their tasks. There are several tests to measure kidney function, the most common of which is the glomerular filtration rate (GFR). The GFR indicates how much blood the kidneys can filter each minute.
How is Kidney Function Measured?
Kidney function is typically measured through blood and urine tests. The most common are:
- Blood urea nitrogen (BUN): Measures the level of urea in the blood, a waste product of protein metabolism.
- Creatinine in Serum: Measures the amount of creatinine in the blood. Creatinine is a waste product produced by muscle metabolism and is constantly filtered by the kidneys.
- Estimated Glomerular Filtration Rate (eGFR): Calculations used to estimate kidney filtration efficiency, often derived from creatinine values, age, sex, and race.
What are Normal Kidney Function Values?
Normal values may vary depending on the lab, but here are general guidelines:
- eGFR: A normal eGFR value is above 90 ml/min/1.73 m². Values between 60-89 ml/min/1.73 m² may indicate mild renal impairment, depending on other factors such as age and presence of other medical conditions.
- Creatinine in Serum: Normal values can range between 0.7 and 1.2 mg/dL for men and between 0.5 and 1.1 mg/dL for women. These values may vary depending on muscle mass and other factors.
- Blood urea nitrogen (BUN): Normal BUN levels are between about 7 and 20 mg/dL, depending on age and sex. https://www.bloodtesting.nl/bun-stikstoftest-van-het-bloedureum-en-creatinine.html
What To Do When Deviating Values?
- Elevated Creatinine or BUN: This may be an indication of impaired kidney function. Possible causes include dehydration, kidney disease, or other medical conditions.
- Decreased eGFR: This may indicate chronic kidney disease. An eGFR below 60 ml/min/1.73 m² that persists for more than 3 months is usually classified as chronic kidney disease.
