The kidneys are responsible for the excretion of most of the end products of bodily metabolism. They control the concentration of most of the constituents of bodily fluids which determines the acid alkaline base of the body. The kidneys also help regulate the blood pressure.
Urea is formed in the liver and is the final by-product of protein catabolism (breakdown). The level of urea fluctuates with the amount of dietary protein. Urea will be increased with high dietary intake of protein or reduced kidney excretion and may indicate kidney dysfunction (further testing would be required). It can also be used as an indicator of dysbiosis due to ammonia production (from putrefactive action of microbes on nitrogens in the colon) being converted to urea by the liver.
Uric acid (also called urea) is a product of the metabolic breakdown of purine nucleotides (found in the foods liver, anchovies, sardines, dried beans, and beer), and it is a normal component of urine. The major site of uric acid formation is the liver; however, many tissues contribute to the output. Uric acid is mainly excreted by the kidneys but also through the intestines and biliary route. High blood concentrations of uric acid can lead to gout and are associated with other medical conditions, including diabetes, atherosclerosis and kidney insufficiency or kidney stones. We would also look at creatinine.
Uric acid forms ions and salts known as urates and acid urates which can accumulate in the joints and cause gout.
Estimated Glomerular Filtration Rate (e/GFR) is calculated from blood test results using a formula that looks at the level of creatinine (a waste product) in your blood. Low levels indicate kidney insufficiency and results consistently below 60mL/min/1.73m2 indicate chronic kidney disease.