Serum cystatin C as a marker of renal function in critically ill patients with normal serum creatinine.
BACKGROUND
Serum creatinine as a classic marker of renal function has several limitations in the detection of renal dysfunction.


OBJECTIVE
This study assessed the validity of serum cystatin C as a marker of renal function in critically ill patients with normal serum creatinine.


METHODS
Eighty adult patients referred to intensive care units with serum creatinine levels < 1.5 mg/dL and without hemodynamic instability were chosen and their serum creatinine and cystatin C levels were measured. A 24-hour urine sample was collected to calculate creatinine clearance (Ccr). Renal dysfunction was defined as Ccr < 80 mL/min/1.73 m(2).


RESULTS
There were significant correlations between measured Ccr and 1/serum creatinine (R = 0.51, P < 0.001) and 1/serum cystatin C (R = 0.25, P = 0.028). The difference between false negative rates of serum creatinine (93.33%) and cystatin C (80%) in the detection of renal dysfunction was significant (P = 0.032). Receiver operating characteristic curve analysis illustrated that area under the curve of serum creatinine and cystatin C for detecting renal dysfunction were 0.711 and 0.607, respectively; however, this difference was not significant (P = 0.222).


CONCLUSIONS
Our data demonstrated that serum cystatin C is not superior to serum creatinine in the early detection of renal dysfunction in critically ill patients.
Nephrology Urology Research Center and Department of Internal Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
Mohammad Mahdi
MM
Sagheb
Department of Clinical Pharmacy, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, IR Iran.
Soha
S
Namazi
Transplant Research Center and Department of Pathology, Shiraz University of Medical Sciences, Shiraz, IR Iran.
Bita
B
Geramizadeh
Department of Dermatology, Imam Khomeini Hospital, Jundishapur University of Medical Sciences, Ahvaz, IR Iran.
Amin
A
Karimzadeh
Department of Clinical Pharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, IR Iran.
Mohammad Bagher
MB
Oghazian
Department of Clinical Pharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, IR Iran.
Iman
I
Karimzadeh
Acute Kidney Injury; Creatinine; Critically Ill; Cystatin C; Patients