Changes in serum phosphorus level in patients with severe burns: A prospective study

Background: The second most abundant mineral in the body, phosphorus (P), is absorbed in the small intestine after ingestion enhanced by 1,25- dihydroxy vitamin D, and its excretion is exclusively regulated by the kidney. It is clinically significant, aside from its disturbance in burn ICU patient's P mechanism. The increasing rate of morbidity and mortality among the patients can be associated with severe hypophosphatemia. The current study aimed at investigating the changes in serum P levels in the early period after burns, the relationship between serum P level and TBSA (total body surface area) of burn, and the impact of hypophosphatemia on patients' clinical outcomes. Material and methods: The current prospective, observational study was conducted on 137 patients hospitalized in the burn intensive unit (BICU) of Velayat Sub-specialty Burn and Plastic Surgery Center from December 2015 to May 2017. According to the TBSA percentage, the patients were divided into three groups. The level of serum P was determined in the 1st, 3rd, 5th, 7th, and 9th days of hospital stay and before discharge. To evaluate the trend of P changes in the sixtime-points, the average changes along with 95% confidence intervals (CI) were used for multivariate analysis of variance with repeated measures (repeated measures ANOVA). A P-value of 0.05 or less was considered statistically significant. The analyses were performed using SPSS software, version 19 (SPSS Inc.). Results: Totally, 137 patients (70% male, mean age 32 +/- 21years, and TBSA 32.6 +/- 14%) were included in the study. The overall incidence of hypophosphatemia was 75.1%. Hypophosphatemia developed as early as 1.66 f 0.136 (95%CI: 1.4-1.9) days after injury. The highest decrease in the serum P level was observed on the 3rd and 5th days after burn as 2.78 mg/dL and 2.85 mg/dL, respectively (P-value = 0.001). A correlation was observed between TBSA and serum P level. The mean serum P level decreased with increasing the percentage of burns. There was a correlation between serum P level and mortality; therefore, a decrease in serum P level increased the patient's mortality rate (P <0.05). Conclusion: The current study highlighted that hypophosphatemia is often observed in patients with burn injuries during their hospitalization. It is potentially beneficial to identify patients at risk of hypophosphatemia. Therefore, it is suggested that P level be assessed regularly in patients with burn injuries for the timely initiation of P replacement therapy. (C) 2019 Elsevier Ltd and ISBI. All rights reserved.