Creatinine

Clinical significance:

• Assessment of renal function:
  Serum creatinine is routinely used to evaluate how well the kidneys are filtering blood. An increase usually indicates impaired kidney function.
• Diagnosis and monitoring of kidney diseases:
  Elevated creatinine levels are seen in:

Acute kidney injury (AKI)

Chronic kidney disease (CKD)

Glomerulonephritis

Obstructive uropathy

• Estimation of Glomerular Filtration Rate (GFR):
  Creatinine is used to calculate eGFR and creatinine clearance, which give a more accurate measure of renal function than serum creatinine alone.
• Monitoring drug therapy:
  Many drugs are excreted by the kidneys. Creatinine levels help guide dose adjustments and prevent drug toxicity.
• Effect of non-renal factors:
  Creatinine levels may also be influenced by muscle mass, age, sex, diet (high meat intake), dehydration, and strenuous exercise.

Clinical interpretation:

• Increased creatinine: Reduced kidney function, dehydration, shock, urinary obstruction.
• Decreased creatinine: Low muscle mass, pregnancy, severe liver disease (usually of less clinical concern).