Salivary Neutrophil Gelatinase-Associated Lipocalin Sampling Feasibility in Acute Renal Colic

Purpose: Neutrophil gelatinase-associated lipocalin (NGAL) levels in the serum and urine are predictive biomarkers of acute kidney injury with correlation to complication and survival in major surgery. Salivary levels of NGAL during acute renal colic may reflect the degree of renal injury as it appears in different compartments encompassing body response in time perspective. Our aim is to evaluate and examine the feasibility and correlation of salivary NGAL with serum and urine levels in acute renal colic event. Materials and Methods: A prospective controlled study of all patients presenting to the emergency room with acute renal colic event diagnosed with single ureteral stone obstruction by noncontrast CT. Saliva, urine, and blood samples were collected in patients and a control group during the first morning of admission. Results: The study groups consisted of 44 patients and 13 controls, mean age 47 ± 15 years, body mass index 29 ± 6, mean stone size 6 ± 4 mm, mean creatinine levels 1.3 ± 0.7 mg/dL, mean white blood count 10,900 ± 3100 counts per field, and C-reactive protein 29 ± 55. Serum (190 ± 120 ng/mL vs 81 ± 24; p < 0.001) and predominantly salivary (474 ± 185 vs 328 ± 134 ng/mL; p < 0.05) NGAL levels were significantly elevated in patients compared with controls. Conclusions: Salivary NGAL sampling is feasible during the acute phase of renal colic. High levels of salivary NGAL are observed in a single sampling during acute ureteral stone obstruction and may advance clinical decision-making.