Alteração do teor de cálcio no banho de DP para 2,5 mEq/L é eficaz no reestabelecimento dos valores preconizados por diretrizes atuais em pacientes com PTH < 150 pg/dL

International variations in serum PTH and calcium levels and their mortality associations in peritoneal dialysis patients: Results from PDOPPS

BACKGROUND

Mineral bone disorder (MBD) in chronic kidney disease (CKD) is associated with high symptom burden, fractures, vascular calcification, cardiovascular disease and increased morbidity and mortality. CKD-MBD studies have been limited in peritoneal dialysis (PD) patients. Here, we describe calcium and parathyroid hormone (PTH) control, related treatments and mortality associations in PD patients.

METHODS

We used data from eight countries (Australia and New Zealand (A/NZ), Canada, Japan, Thailand, South Korea, United Kingdom, United States (US)) participating in the prospective cohort Peritoneal Dialysis Outcomes and Practice Patterns Study (2014-2022) among patients receiving PD for >3 months. We analysed the association of baseline PTH and albumin-adjusted calcium (calciumAlb) with all-cause mortality using Cox regression, adjusted for potential confounders, including serum phosphorus and alkaline phosphatase.

RESULTS

Mean age ranged from 54.6 years in South Korea to 63.5 years in Japan. PTH and serum calciumAlb were measured at baseline in 12,642 and 14,244 patients, respectively. Median PTH ranged from 161 (Japan) to 363 pg/mL (US); mean calciumAlb ranged from 9.1 (South Korea, US) to 9.8 mg/dL (A/NZ). The PTH/mortality relationship was U-shaped, with the lowest risk at PTH 300-599 pg/mL. Mortality was nearly 20% higher at serum calciumAlb 9.6+ mg/dL versus 8.4-<9.6 mg/dL. MBD therapy prescriptions varied substantially across countries.

CONCLUSIONS

A large proportion of PD patients in this multi-national study have calcium and/or PTH levels in ranges associated with substantially higher mortality. These observations point to the need to substantially improve MBD management in PD to optimise patient outcomes.

LAY SUMMARY

Chronic kidney disease-mineral bone disorder (MBD) is a systemic condition, common in dialysis patients, that results in abnormalities in parathyroid hormone (PTH), calcium, phosphorus and vitamin D metabolism. A large proportion of peritoneal dialysis (PD) patients in this current multi-national study had calcium and/or PTH levels in ranges associated with substantially higher risks of death. Our observational study design limits our ability to determine whether these abnormal calcium and PTH levels cause more death due to possible confounding that was not accounted for in our analysis. However, our findings, along with other recent work showing 48-75% higher risk of death for the one-third of PD patients having high phosphorus levels (>5.5 mg/dL), should raise strong concerns for a greater focus on improving MBD management in PD patients.

A feasibility study of avoiding positive calcium balance and parathyroid hormone increase in patients on peritoneal dialysis

Background

The effect of the dialysate calcium concentration (D[Ca]) on mineral and bone metabolism in patients on peritoneal dialysis (PD) is overlooked. D[Ca] of 1.75 mmol/L is still prescribed to many patients on PD around the world. Previous studies on the effects of reducing D[Ca] have been carried out before the incorporation of calcimimetics in clinical practice. We hypothesized that a reduction in D[Ca] is safe and without the risk of a rise in serum parathyroid hormone (PTH).

Methods

In this non-randomized clinical trial, the D[Ca] was reduced from 1.75 mmol/L to 1.25 mmol/L for one year in prevalent patients on PD. Demographic, clinical, and CKD-MBD-related biomarkers were evaluated at baseline, 3, 6, and 12 months of follow-up.

Results

20 patients completed 1-year follow-up (56 ± 16 years, 50 % male, 25 % diabetic, 55 % with baseline parathyroid hormone – PTH >300 pg/mL). Over time, there was no significant change in calcium, phosphate, total alkaline phosphatase, 25(OH)-vitamin D or PTH, although adjustments in calcitriol and sevelamer prescription were required. After 1 year, absolute and percentual change in PTH levels were 36 (−58, 139) pg/mL, and 20 % (−28, 45) respectively. The proportion of patients with PTH > 300 pg/mL did not change during the follow-up (p = 0.173).

Conclusion

Knowing the risk of a positive calcium balance in patients on PD, reducing the D[Ca] concentration is a safe and valuable option, although medication adjustments are needed to detain PTH rising.

Aluminum-Induced Electrophysiological Variation, Synaptic Plasticity Impairment, and Related Mechanism

Aluminum, an environmentally abundant non-redox trivalent cation, has long been reported to alter blood-brain barrier and gets deposited in different regions of the brain. Many reports strongly indicated that Al had an adverse impact on the central nervous system (CNS), particularly on cognitive ability. Until now, studies in animal models and cell cultures have revealed that Al exposure results in altered behavioral performance and memory damage. The present paper reviews the scientific literature linking aluminum and the impairment of electrophysiological variation and synaptic plasticity. The focus is on the changes of electrical excitability, voltage-operated ion channels, and synaptic plasticity induced by aluminum. A detailed mechanism of the role of aluminum in hippocampal LTP which is the most widely studied example of synaptic plasticity is highlighted. Evidence revealed that glutamate-NO-cGMP, PLC, Ca²⁺-CaM-CaMKII, MAPK, and Wnt pathway may be important in the mechanism underlying Al-induced long-term memory impairment. Further studies are required to establish the upstream activators and downstream effectors of these cascades and to answer how so many signaling cascades relate to the other signaling processes that might be involved in the Al-induced inhibition of synaptic plasticity.