Glomerular Filtration Surrogates: BUN, Creatinine, SDMA

These flashcards cover key concepts related to glomerular filtration, GFR markers, and renal function assessment.

Glomerular Filtration Rate (GFR)

A measure of renal function, particularly functional renal mass.

Ideal GFR marker

Inulin, which must be infused; clearance of inulin equals GFR.

Filtration Fraction (FF)

The fraction of renal plasma flow (RPF) filtered across glomerular capillaries, calculated as FF = GFR/RPF.

Serum creatinine

A product of muscle metabolism used as a marker for GFR; increases when over 75% of functional nephrons are lost.

Blood Urea Nitrogen (BUN)

Synthesized in the liver; end-product of protein catabolism; levels can indicate renal function when assessed alongside creatinine.

BUN:Creatinine ratio

Used to evaluate renal function; changes can indicate renal or non-renal causes of azotemia.

Symmetrical Dimethylarginine (SDMA)

A kidney function biomarker that increases earlier than creatinine and is not affected by muscle mass.

Hyperphosphatemia

Increased serum phosphorus concentrations as GFR decreases in chronic kidney disease (CKD).

Best practice for assessing kidney function

Involves a comprehensive approach including history, physical examination, urinalysis, and multiple biomarkers.