RENAL-GFR MEASUREMENT

SUMMARY

1. Creatinine clearance: using 24 hour urine collection. But difficulties with accurate collection.

2. Exceeds true GFR by 10 to 20% due to tubular secretion.

3. Tubular secretion increases with drop in GFR: up to 50% in Near End Stage Renal Failure (NESRF).

4. Equations using serum creatinine: Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI).

5. More accurate that MDRD and Cockcroft-Gault equations in normal or near-normal GFR but MDRD better for low levels of GFR.

6. Isotopic measurement of GFR using a radioactive tracer (DTPA nuclear medicine test): accurate but cumbersome and expensive. Used mostly in transplant donor workup.

Reference(s)

Barrett, K.E., Barman, S.M., Boitano, S., Brooks, H.L., Weitz, M., Brian Patrick Kearns, Ganong, W.F. and Mcgraw-Hill Education (Firm (2016). Ganong’s review of medical physiology. 25th ed. New York: Mcgraw Hill Education.
Hall, J.E. and Hall, M.E. (2020). Guyton And Hall Textbook Of Medical Physiology. 14th ed. S.L.: Elsevier - Health Science.
West, J.B. and Luks, A.M. (2021). West’s Pulmonary Pathophysiology. Lippincott Williams & Wilkins.