Elevated serum phosphate and parathyroid hormone (PTH) concentrations are associated with cardiovascular events, bone disease, and mortality in patients on maintenance hemodialysis. Although circadian changes are known in people with CKD, it is unknown whether differences occur in these parameters over the course of a day in people receiving hemodialysis.

We used clinical data from Fresenius Medical Care US dialysis clinics to determine how the time of day when measurements were collected (hemodialysis treatment start time) may be associated with serum phosphate and PTH concentrations. We used harmonic regression to assess these associations while accounting for demographic data and treatment parameters.

A total of 96,319 patients receiving maintenance hemodialysis were included in this analysis. Patients had a mean age of 64±14 years, 43% were women, and dialysis start times ranged from 3:00 am to 7:59 pm. The mean serum phosphate concentration was 5.2±1.5 mg/dl, and the median PTH was 351 pg/ml (interquartile range [IQR], 214–547). In fully adjusted models, serum phosphate had a nadir at 11:00 am of 4.97 (IQR, 4.94–5.01) mg/dl and a peak at 7:00 pm of 5.56 (IQR, 5.50–5.62) mg/dl. Serum PTH had a nadir at 9:00 am of 385 (IQR, 375–395) pg/ml and a peak at 7:00 pm of 530 (IQR, 516–547) pg/ml.

Among patients receiving maintenance hemodialysis, concentrations of PTH and phosphate before a dialysis session vary with the time of day that these values are measured. Consideration of whether these values were obtained at peak or nadir times of the day may be important in treatment decisions.

血清磷酸盐和甲状旁腺激素 (PTH) 浓度升高与维持性血液透析患者的心血管事件、骨病和死亡率有关。尽管 CKD 患者的昼夜节律变化是已知的，但尚不清楚接受血液透析的人在一天中这些参数是否会发生差异。

我们使用来自 Fresenius Medical Care 美国透析诊所的临床数据来确定一天中收集测量值的时间（血液透析治疗开始时间）如何与血清磷酸盐和 PTH 浓度相关。我们使用调和回归来评估这些关联，同时考虑人口统计数据和治疗参数。

共有 96,319 名接受维持性血液透析的患者被纳入该分析。患者的平均年龄为 64±14 岁，43% 为女性，透析开始时间为 3:00是至 7:59下午. 平均血清磷酸盐浓度为 5.2±1.5 mg/dl，中位 PTH 为 351 pg/ml（四分位距 [IQR]，214–547）。在完全调整的模型中，血清磷酸盐在 11:00 达到最低点是为 4.97 (IQR, 4.94–5.01) mg/dl，峰值出现在 7:00下午5.56 (IQR, 5.50–5.62) 毫克/分升。血清 PTH 在 9:00 达到最低点是385 (IQR, 375–395) pg/ml，峰值出现在 7:00下午530 (IQR, 516–547) pg/ml。

在接受维持性血液透析的患者中，透析前 PTH 和磷酸盐的浓度随一天中测量这些值的时间而变化。考虑这些值是在一天中的高峰时间还是最低时间获得，对于治疗决策可能很重要。