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Abstract: FR-PO642

Changes in Serum Phosphate Levels Associated with In-Hospital Mortality

Session Information

Category: Fluid and Electrolytes

  • 902 Fluid and Electrolytes: Clinical


  • Thongprayoon, Charat, Mayo Clinic, Rochester, Minnesota, United States
  • Cheungpasitporn, Wisit, University of Mississippi Medical Center, Jackson, Mississippi, United States
  • Mao, Michael A., Mayo Clinic, Rochester, Minnesota, United States
  • Kashani, Kianoush, Mayo Clinic, Rochester, Minnesota, United States

Fluctuations in serum phosphate levels have recently been shown to be associated with coronary calcification and increased mortality in end-stage renal disease (ESRD) patients. However, the impacts of serum phosphate changes in hospitalized patients remain unclear. This study aimed to test the hypothesis that serum phosphate changes during hospitalization were associated with in-hospital mortality.


We included all adult hospitalized patients from January 2009 to December 2013 that had at least two serum phosphate measurements during their hospitalization. We categorized the hospital serum phosphate change, which was defined as the absolute difference between the highest and lowest phosphate, into 5 groups: 0-0.6, 0.7-1.3, 1.4-2.0, 2.1-2.7, ≥2.8 mg/dL. , Using the phosphate change group of 0-0.6 mg/dL as the reference group, the adjusted odds ratio of in-hospital mortality for various phosphate change groups was obtained by multivariable logistic regression analysis.


A total of 28,149 patients were studied. The in-hospital mortality in patients with phosphate change of 0-0.6, 0.7-1.3, 1.4-2.0, 2.1-2.7, ≥2.8 mg/dL was 1.5, 2.0, 3.1, 4.4, and 10.7%, respectively (p<0.001). When adjusted for potential confounders, a larger phosphate change was associated with progressively increased in-hospital mortality with ORs of 1.35 (95% 1.04-1.74) in 0.7-1.3 mg/dL, 1.98 (95% CI 1.53-2.55) in 1.4-2.0 mg/dL, 2.68 (95% CI 2.07-3.48) in 2.1-2.7 mg/dL, and 5.4 (95% CI 3.94-6.45) in ≥2.8 mg/dL compared to the phosphate change group of 0-0.6 mg/dL. A similar result was noted when we further adjusted for either the lowest, highest or admission phosphate.


Greater serum phosphate changes during a patient’s hospitalization were progressively associated with increased in-hospital mortality.