#Bun levels normal range update#

These eGFR equations are superior to serum creatinine alone since they include race, age, and gender variables. Serum creatinine is also utilized in GFR estimating equations such as the Modified Diet in Renal Disease (MDRD) and the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. Additionally, serum creatinine is a later indicator of renal impairment-renal function is decreased by 50% before a rise in serum creatinine is observed. As GFR increases in pregnancy, lower creatinine values are found in pregnancy. Creatinine can change as much as 30% after the ingestion of red meat. Thus, there is a difference in creatinine ranges between males and females with lower creatinine values in children and those with decreased muscle bulk. The amount of creatinine produced per day depends on muscle bulk. Decreased clearance by the kidney results in increased blood creatinine. For the most part, creatinine is cleared from the blood entirely by the kidney. Furthermore, due to tubular secretion, creatinine overestimates GFR by around 10% to 20%.Ĭreatinine is the by-product of creatine phosphate in muscle, and it is produced at a constant rate by the body. Improper or incomplete urine collection is one of the major issues affecting the accuracy of this test hence timed collection is advantageous. ml/min), and P = plasma concentrationĬreatinine clearance should be corrected for body surface area. Creatinine clearance is then calculated using the equation:Ĭ = clearance, U = urinary concentration, V = urinary flow rate (volume/time i.e. The calculated clearance of creatinine is used to provide an indicator of GFR. This involves the collection of urine over a 24-hour period or preferably over an accurately timed period of 5 to 8 hours since 24-hour collections are notoriously unreliable. The most commonly used endogenous marker for the assessment of glomerular function is creatinine. The inconvenience associated with the use of exogenous markers, specifically that the testing has to be performed in specialized centers, and the difficulty to assay these substances, has encouraged the use of endogenous markers. The most promising exogenous marker is the non-radioactive contrast agent, iohexol, especially in children. Other exogenous markers used are radioisotopes such as chromium-51 ethylene-diamine-tetra-acetic acid (51 Cr-EDTA), and technetium-99-labeled diethylene-triamine-pentaacetate (99 Tc-DTPA). It involves the infusion of inulin and then the measurement of blood levels after a specified period to determine the rate of clearance of inulin. Assessment of GFR using inulin, a polysaccharide, is considered the reference method for the estimation of GFR. It should not undergo extrarenal elimination.Īs no such endogenous marker currently exists, exogenous markers of GFR are used.

#Bun levels normal range update#

This article provides an update on the relevant biochemical tests for the assessment of renal function.

Worldwide, the most common causes of CKD are hypertension and diabetes. According to the National Institutes of Health, the overall prevalence of chronic kidney disease (CKD) is approximately 14%. Tests of renal function have utility in identifying the presence of renal disease, monitoring the response of kidneys to treatment, and determining the progression of renal disease. Assessment of renal function is important in the management of patients with kidney disease or pathologies affecting renal function. The functional unit of the kidney is the nephron, which consists of the glomerulus, proximal and distal tubules, and collecting duct. The kidneys play a vital role in the excretion of waste products and toxins such as urea, creatinine and uric acid, regulation of extracellular fluid volume, serum osmolality and electrolyte concentrations, as well as the production of hormones like erythropoietin and 1,25 dihydroxy vitamin D and renin.