A case of transient elevation of creatinine caused by severe hyperuricemia

Background: To explore the underlying causes of significant fluctuations in creatinine levels within three days due to transient and severe uric acid elevation, and to provide evidence for the interpretation of abnormal test results and clinical diagnosis and management.

Methods: The issues were resolved by retesting the samples, comparing results across different detection platforms, and analyzing the reaction curve. We comprehensively reviewed patients' general conditions, imaging examinations, and treatments. Additionally, we compared pre- and post-admission changes in laboratory indices and performed an extensive literature search for comprehensive analysis.

Results: At the patient's first visit, the levels of uric acid (UA), creatinine (CR), and urea (UREA) were measured at 891 umol/L, 211 umol/L, and 7.8 mmol/L, respectively using a Roche full-automatic biochemical analyzer and its corresponding reagents. Subsequent testing yielded 917 umol/L, 211 umol/L, and 8.3 mmol/L for UA, CR, and UREA. After retesting with the Beckman automatic biochemical analyzer and its corresponding reagents, the results for UA, CR, and UREA were 1013 umol/L, 221 umol/L, and 7.75 mmol/L, respectively. The results of the two detection systems were in agreement. A supplementary measurement of Cystatin C (CYSC) at 1.69 mg/L indicates renal dysfunction, consistent with the observed increase in CR levels and ruling out false elevation due to assay-related issues. At 48 h post-admission, untreated, the levels of blood UA, CR, and UREA decreased to 567umol/L, 77umol/L, and 5.1 mmol/L, respectively. Through literature review and analysis, it was determined that the transient abnormal increase in the patient's creatinine level may be attributed to a substantial accumulation of uric acid crystals obstructing the renal tubules, leading to an impediment in renal tubular excretion which subsequently resolves spontaneously.

Conclusion: Severe hyperuricemia may result in a transient increase in blood CR levels and could potentially lead to the development of acute uric acid nephropathy. When a clinical laboratory encounters test results inconsistent with the clinical manifestations, it is essential to not only address any potential detection issues but also proactively investigate the underlying reasons for abnormal test results through comprehensive literature reviews and other rigorous methodologies.