A kidney function blood test gives us an insight into how well the kidneys are working by including the main biomarkers filtered and regulated by the nephrons: urea, creatinine, and electrolytes.
Urea: this biomarker is a waste product from protein metabolism that is filtered by the kidneys and mostly eliminated through the urine, making it useful for screening renal health. It also provides information on hydration status.[5]
Creatinine: kidney function assessment is heavily based on creatinine levels. Its concentration is determined by the production (muscle metabolism) and elimination (kidney function) rates, serving as a relatively stable and easy-to-measure biomarker. Conveniently, as it is filtered out by the kidneys, creatinine’s clearance rate can be used to estimate the glomerular filtration rate (eGFR).[6]
eGFR: this value represents how well the kidneys are filtering blood and, thus, gives us critical information on kidney health and function. Most frequently, it is calculated with the help of creatinine levels and other variables, such as sex, age, and race. Glomerular filtration can be measured with even higher accuracy, but this requires costly, cumbersome, and invasive methods (such as intravenous injection of inulin, radioactive substances, or radio-contrast agents).[6]
Electrolytes: cells require a strict electrolyte balance to work. Sodium, potassium, chloride, and bicarbonate are vital electrolytes for the human body and their regulation is tightly linked to kidney health. They are in charge of maintaining water and acid-base balance, as well as promoting the transportation of nutrients, elimination of cellular waste products, and even cardiac muscle contraction. Other important electrolytes include calcium, magnesium, and phosphate; however, they are only ordered when a problem is suspected.[7]
Note, as detailed above electolytes are not included in a kidney test at home, these require a visit to the Patient Reception for immediate analysis. You can select this at checkout.