Variação do fósforo sérico em pacientes com doença renal crônica em hemodiálise conforme horário da coleta e esquema semanal de sessões

Abstract

Introduction: Chronic Kidney Disease (CKD) is defined as the change in the Glomerular Filtration Rate (GFR) below 60 ml/min/1.73m2, and/or the presence of kidney damage determined by proteinuria/structural damage, with implications for health and duration over 3 months. The mineral and bone disease (MBD) is one of the main complications of CKD, and fluctuations in phosphorus (P) are considered risk factors for cardiac death and cardiovascular events in this population. Monitoring of serum P in CKD is important, but little is known about the circadian variation of mineral and bone variables in this population. Objective: To analyze the variation in serum P concentration in patients with CKD undergoing hemodialysis according to the time of measurement and weekly schedule of sessions. Material and methods: We evaluated the electronic medical records of all patients undergoing hemodialysis at the Hospital das Clínicas HCFMUSP, Universidade de São Paulo, in São Paulo, between January 2017 and December 2017 to collect biochemical data. We asked a question related to fasting to each patient. We correlated the variation in serum phosphorus values with time and state of fasting at the time of laboratory measurement, and with the weekly dialysis scheme. Results: 1,354 serum P measurements were evaluated, 15.3% and 37.5% of the measurements had the P below the limit of normality (3.5 to 5.5 mg/dL), respectively. According to the circadian rhythm, we analyzed the morning shift against the afternoon + night shift, combined. The P measurements of patients who performed the collection in the morning were higher throughout the year, reaching significance in the months of February, April, July, September, and December. The result of the multivariate analysis showed the independent role of the dialysis shift, PTH, and the use of Sevelamer in the serum concentration of phosphorus. Conclusion: Changes in serum P levels are common in patients with CKD, with hyperphosphatemia being the most evident change. We verified that the highest serum P level occurs in the morning when compared to the afternoon and evening, a result that denotes the impact of the circadian rhythm in the P control.