Emergency Medicine Practice Test 2026 – Complete Exam Preparation

Serum creatinine is the most critical lab value when assessing for acute kidney injury (AKI). This is because creatinine is a waste product produced by muscle metabolism and is usually removed from the blood by the kidneys. When there is a decrease in kidney function, the serum creatinine levels rise, serving as a key indicator of renal impairment.

An increase in serum creatinine is often one of the earliest signs of AKI, and its measurement is a standard part of the diagnostic process. In clinical practice, a significant change in serum creatinine—typically, an increase of 0.3 mg/dL or more within 48 hours or a 50% increase from baseline within the past week—can indicate AKI.

While blood urea nitrogen can also indicate kidney function, it is less specific and sensitive than serum creatinine for detecting acute changes. The electrolyte panel is valuable for identifying abnormalities that can arise from kidney dysfunction but does not directly indicate the level of kidney injury. Glomerular filtration rate (GFR) is a crucial measure of kidney function, particularly for chronic conditions, but it is typically derived from serum creatinine levels rather than serving as a direct measure in acute situations. Thus, the specificity and direct correlation of serum