Increased Plasma Osmolar Gap Is Predictive of Contrast-Induced Acute Kidney Injury

Increased Plasma Osmolar Gap Is Predictive of Contrast-Induced Acute Kidney Injury

SEJOONG KIM,^1,2 JIYOON SUNG,³ WOONG CHUL KANG,³ SHIN YOUNG AHN,^1,2 DONG KI KIM,^2,4 HO JUN CHIN,^1,2 KI YOUNG NA,^1,2 KWON WOOK JOO,^2,4 DONG-WAN CHAE^1,2 and JIN SUK HAN^2,4

¹ Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
² Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
³ Department of Internal Medicine, Gachon University Gil Hospital, Incheon, Korea
⁴ Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea

Contrast-induced acute kidney injury (CIAKI) is a common complication after percutaneous coronary artery intervention (PCI). It is urgent to find a novel, easily measurable and accurate predictor for the early detection of CIAKI. Hyperosmolarity and large amounts of contrast media are risk factors for CIAKI. However, there is no study on plasma osmolar gap as a predictor of CIAKI. We enrolled 89 patients undergoing elective PCI and tested changes of serum sodium, osmolar gap, and renal function at 0, 6, 12 and 24 hours. Plasma osmolar gap was calculated using the following formula: measured plasma osmolarity - [2(Na) + serum urea nitrogen/2.8 + glucose/18]. CIAKI was defined as follows: increase in serum creatinine of ≥ 50%, increase in serum creatinine of ≥ 0.3 mg/dL, or decrease in estimated glomerular filtration rate of ≥ 25% within 24 hours after PCI. The incidence of CIAKI was 13.5% (12/89 patients). The CIAKI group had higher plasma osmolar gaps 6 hours after PCI. The adjusted hazard ratio of the plasma osmolar gap from hour 6 (1-mOsm/L increments) to the development of CIAKI was 1.12 (95% confidence interval [CI], 1.01-1.26; P = 0.041). Sensitivity and specificity of 7 mOsm/L or higher plasma osmolar gap at hour 6 were 70.0% and 76.6%, respectively (area under the ROC curve = 0.77 [95% CI, 0.65-0.89]). Increased plasma osmolar gap may precede the development of CIAKI in patients undergoing PCI. In conclusion, plasma osmolar gap may be a useful predictor for the development of CIAKI.

keywords —— acute kidney injury; biomarker; contrast media; coronary angiography; osmolality

===============================

Tohoku J. Exp. Med., 2012, 228, 109-117

Correspondence: Jin Suk Han, M.D., Ph.D., Department of Internal Medicine, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea.

e-mail: jshan@snu.ac.kr