Assessment of Renal insufficiency in patients with normal serum creatinine levels undergoing angiography

Objective: To determine the frequency of patients with underlying renal insufficiency having normal serum creatinine level proceeding for coronary angiography. Methods: A total of 693 patients from September 2009 to February 2010 undergoing diagnostic coronary angiography at the National Institute of Cardiovascular Diseases (NICVD) with normal serum creatinine 1.5mg/dl were selected. Glomerular filtration rate (GFR) was calculated for each patient using the Cockcroft-Gault (C-G) equation and a GFR 80ml/min was labeled as renal insufficiency. Results: The mean age of males was 51.86±10.19 years and 51.52 ± 9.80 years for females. Almost one-third (n=236, 34.1%) of patients had GFR 80ml/min; comparison between male (n=168, 31.2%) and female (n=68, 43.9%) was significant (p-value 0.003). Age group breakdown showed majority of patients (n=196; 83.05%) with GFR 80 ml/min ranged between 40-69 years (p-value 0.001). Conclusion: This study has shown that most of the patients with normal serum creatinine have abnormal GFR. Serum creatinine, which is considered to be an important screening test in patients with renal impairment, might remain in the normal range despite the renal function being significantly impaired. Therefore, GFR should be considered as an estimate of renal insufficiency, regardless of serum creatinine levels being in normal range.