Objective: To assess the correlation between urea and mortality in acutely ill medical patients admitted to hospital.

Methods: We included consecutively admitted adult patients from the medical admission unit at a regional Danish hospital. Data on mortality was extracted. The association with 30-day mortality was described using cubic splines, and discriminatory power, crude association and adjusted analyses were performed.

Results: We included 5,894 patients, with a 30-day mortality of 5.6%. We found a dose-response relation between urea and 30-day mortality with an increase from 2.7% to 19.5% (p<0.001).

Conclusion: Elevated urea is strongly associated with 30-day all-cause mortality in acutely admitted medical patients with acceptable discrimination and good calibration.

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