Navigating an unexpected creatinine result during a pre-intravenous contrast renal function workup.

Background: Increasing chronic disease incidence drives intravenous (IV) contrast-based diagnostic imaging. While IV procedure is largely safe, contrast-induced neuropathy risk in patients with predisposing factors demand pre-IV renal assessment. Although common, point-of-care creatinine (POC) tests are prone to generating ambiguous results. This frequently result in time-consuming retests, rescheduled appointments, patient distress, and healthcare burdens.

Case Presentation: A diabetic, hypertensive, and chronic kidney diseased Caucasian male, aged 61, presented for a scheduled intravenous contrast-enhanced computed tomography scan. His initial POC-based creatinine result of 1.20 mg/dL (106.1 μmol/L) narrowly exceeded the reference interval (0.67---1.17 mg/dL [59.2 - 103.5 μmol/L]). Given the patient's pre-existing conditions, laboratory-based creatinine test was performed to reassure his renal function. The new result was found to be 0.95 mg/dL (84 μmol/L), which fell within the normal reference interval. This substantial disparity of 0.25 mg/dL (22.1 μmol/L; 20.8 %) between creatinine tests while delaying the intravenous procedure prompted the clinicians to request an in-depth laboratory investigation.

Conclusion: Comprehensive analysis using patient-centered metrics such as index of individuality, reference change value, and subject-based reference interval alleviated the concerns on his renal health and disparity in assay results (<0.3 mg/dL≡ <26.5 μmol/L) total allowable error limit), thus allowing intravenous contrast imaging.