Serum Cystatin C for Early Detection of Acute Kidney Injury After Primary Percutaneous Coronary Intervention

Acute Kidney Injury (AKI) is defined as an absolute increase in serum creatinine ≥0.3 mg/dl (≥26.4 μmol/l), a percentage increase in serum creatinine ≥50% (1.5-fold from baseline), or a reduction in urine output (documented oliguria < 0.5 ml/kg/hour for > 6 hours) Serum creatinine which is considered the gold standard currently for diagnosis of AKI remains unchanged until 50% of kidney function falls down. It is affected by non-specific factors like diet, age, dehydration, muscle mass, gender, and drugs There were evidences of the association between AKI and acute coronary syndrome (ACS); First, AKI detection may be missed by cardiologists. Physicians tend to disregard mild or transient serum creatinine elevation during hospital stay for ACS, and they often attribute small serum creatinine increases to laboratory variations.

Cystatin C (CysC), a cystatin protease inhibitor, is less affected by non-specific factors. When GFR decreases, CysC begins to increase. CysC was recommended to be measured in addition to creatinine in GFR estimation.

Inclusion criteria

• Age ≥ 18 years.
• Patient with absolute increase in serum creatinine ≥0.3 mg/dl (≥26.4 μmol/l) or with percentage increase in serum creatinine ≥50% (1.5-fold from baseline)
• Patient with reduction in urine output (documented oliguria < 0.5 ml/kg/hour for > 6 hours)
• Patient with typical chest pain, ECG changes, Echocardiogram positive finding

Exclusion criteria

• History of nephrectomy
• patient with renal transplantation
• patient with renal replacement therapy initiated before admission
• patient with chronic kidney disease
• patient on regular haemodialysis
• patient known to be diabetic