Estimated Glomerular Filtration Rate (eGFR)
Renal function is an indication of the state of the kidney and its role in renal physiology. Unfortunately, blood urea nitrogen (BUN) and creatinine will not be raised above the normal range until 60% of total kidney function is lost. Hence, the more accurate estimated glomerular filtration rate (eGFR) is measured whenever renal disease is suspected and is important in grading of chronic renal insufficiency. eGFR is estimated by formulas using just a blood test result.
Risk factors for kidney disease include diabetes, high blood pressure, family history, older age and ethnic group.
For most patients, eGFR over 60 mL/min is adequate. But, if the eGFR has significantly declined from a previous test result, this can be an early indicator of kidney disease requiring medical intervention. The sooner kidney dysfunction is diagnosed and treated, the greater odds of preserving remaining nephrons, and preventing the need for dialysis.
eGFR can increase due to hypoproteinemia because of the reduction in plasma oncotic pressure. eGFR can also increase due to constriction of the efferent arteriole but decreases due to constriction of the afferent arteriole. Non-steroidal anti-inflammatory drugs (NSAIDs) prevent the production of prostaglandins, molecules which dilate the afferent arteriole, NSAIDs could therefore worsen kidney function by decreasing afferent blood flow to the Bowman's capsule.
The normal ranges of eGFR, adjusted for body surface area, are:
· Males: 70 ± 14 mL/min/1.73m2
· Females: 60 ± 10 mL/min/1.73m2
Chronic Kidney Disease Stages
The severity of chronic kidney disease (CKD) is described by 6 stages, the most severe three are defined by the eGFR value, and first three also depend whether there is other evidence of kidney disease (e.g. proteinuria):
0)- Normal kidney function: eGFR above 90mL/min/1.73m2 and no proteinuria
1)- CKD1: eGFR above 90mL/min/1.73m2 with evidence of kidney damage
2)- CKD2 (Mild): eGFR of 60 to 89 mL/min/1.73m2 with evidence of kidney damage
3)- CKD3 (Moderate): eGFR of 30 to 59 mL/min/1.73m2
4)- CKD4 (Severe): eGFR of 15 to 29 mL/min/1.73m2
5)- CKD5 Kidney failure (dialysis or kidney transplant needed): eGFR less than 15 mL/min/1.73m2
Estimated Glomerular Filtration Rate (eGFR) is now routinely done with serum creatinine level assay in Saridar Lab.