A creatinine serum test measures the level of creatinine, a waste product produced by muscle breakdown, in your blood.Creatinine is normally filtered from the blood by the kidneys and excreted in urine.Elevated creatinine levels can indicate impaired kidney function.This test is essential for assessing kidney health, diagnosing kidney disease, monitoring the progression of kidney conditions, and evaluating the effectiveness of kidney treatments.

Cystatin C is a small protein produced by most cells in the body.It is freely filtered by the kidneys, making it a reliable marker of kidney function, even in individuals with normal creatinine levels.Unlike creatinine, cystatin C production is not influenced by muscle mass or diet, providing a more accurate assessment of glomerular filtration rate (GFR), a measure of kidney function.Elevated cystatin C levels can indicate kidney damage or dysfunction, even in the early stages of chronic kidney disease.

NEUTROPHIL GELATINASE ASSOCIATED LIPOCALCIN (NGAL) IS A LEADING NEW BIOMARKER OF ACUTE KIDNEY INJURY (AKI). NGAL CAN BIND TO IRON SIDEROPHORE COMPLEXES AND MAY HAVE TISSUE PROTECTIVE EFFECTS IN THE PROXIMAL TUBULE. IT IS HIGHLY UPREGULATED AFTER INFLAMMATION AND KIDNEY INJURY AND CAN BE DETECTED IN URINE WITHIN 2 HOURS OF CARDIOPULMONARY BYPASS ASSOCIATED AKI. SPECIFICITY OF NGAL IN CASES OF SEPSIS AND PYURIA NEEDS TO BE ESTABLISHED.

FRACTIONAL EXCRETION OF SODIUM (FENA) IS THE FRACTION OF FILTERED SODIUM LOAD THAT IS REABSORBED BY THE TUBULES AND IS A MEASURE OF BOTH THE KIDNEYS ABILITY TO REABSORB SODIUM AS WELL AS ENDOGENOUS AND EXOGENOUS FACTORS THAT AFFECT TUBULAR REABSORPTION. WITH PRERENAL AZOTEMIA, FENA IS USUALLY <1% SUGGESTING AVID TUBULAR SODIUM REABSORPTION. LOW FENA IS OFTEN SEEN IN GLOMERULONEPHRITIS, HENCE SHOULD NOT BE CONSIDERED SYNONYMOUS WITH INTRAVASCULAR VOLUME DEPLETION AND SHOULD NOT BE USED AS A SOLE GUIDE FOR VOLUME MANAGEMENT. IN ISCHEMIC AKI, FENA IS FREQUENTLY >1% BECAUSE OF TUBULAR INJURY AND RESULTANT INABILITY TO REABSORB SODIUM.