Serum Creatinine as an Index of Renal Function: New Insights into Old Concepts

Key Points

• To review the physiological, metabolic, and analytical factors that influence serum creatinine concentration and evaluate its reliability as a surrogate marker of glomerular filtration rate (GFR).
• Synthesized fundamental principles of renal physiology, creatinine metabolism, and analytical chemistry affecting serum creatinine levels.
• Evaluated the impact of clinical variables—including aging, pregnancy, diabetes mellitus, pharmacotherapy, and acute versus chronic renal failure—on creatinine interpretation.
• Identified that non-GFR determinants, including tubular secretion, metabolic generation rates, and assay interferences, substantially alter serum creatinine concentrations.
• Demonstrated that clinical states such as pregnancy, aging, and specific drug regimens distort the relationship between serum creatinine and true kidney function.
• Established that while serum creatinine provides practical utility for routine clinical monitoring, more accurate renal clearance measures are frequently required.