Kidney
BUN / Creatinine Ratio
What This Marker Tells Us
Compares these two waste products, revealing whether elevations reflect dehydration, kidney problems, or high protein intake.
Why It Matters
Distinguishes between prerenal causes (dehydration, heart failure), intrinsic kidney disease, and postrenal obstruction better than either marker alone. High ratios with both elevated suggest dehydration or increased protein breakdown. High ratios with normal creatinine indicate prerenal issues. Normal ratios with both elevated suggest intrinsic kidney disease. The pattern guides diagnosis and intervention.
How to Interpret Your Trends
Low ratios (below 10) may indicate overhydration, low protein intake, or liver disease. Typical ratios (10-20) suggest normal kidney function and hydration. Elevated ratios (21-30) indicate dehydration, high protein intake, or prerenal kidney dysfunction. High ratios (above 30) signal significant dehydration, gastrointestinal bleeding, or heart failure requiring medical attention.
What Influences This Marker
Hydration status dramatically affects this ratio; dehydration raises BUN more than creatinine. High protein intake, gastrointestinal bleeding, and catabolic states elevate BUN preferentially. Heart failure reduces kidney perfusion, raising BUN disproportionately. Adequate hydration, balanced protein intake, and cardiovascular health maintain optimal ratios.
How Your Team Uses It
Your coach uses this ratio to determine whether elevated kidney markers reflect reversible causes like dehydration versus true kidney disease. High ratios prompt hydration optimization and protein intake adjustment before assuming kidney dysfunction. It guides whether timing of lab testing around training and nutrition needs adjustment.
Related Signals We Also Review
BUN, creatinine, eGFR, electrolytes, hydration status, protein intake, and cardiovascular function complete the kidney function and hydration assessment.