The effect of dietary phosphorus load and food matrix on postprandial serum phosphate in hemodialysis patients: a pilot study

Still no direct evidence of postprandial hyperkalemia with plant foods

Although St-Jules et al have presented the case for postprandial hyperkalemia with food, including plant foods, there (still) is little to no direct evidence supporting the occurrence of postprandial hyperkalemia, mostly due to a lack of studies performed exclusively using food. Food is different than salts or supplements, and it is likely that a banana behaves differently than potassium salts. A growing body of evidence supports the use of plant foods without causing hyperkalemia in patients with kidney disease. Currently, only 1 study has reported on the postprandial effects of hyperkalemia. In this study, there was a substantial reduction in the instances of postprandial hyperkalemia in participants consuming a diet that included more plant foods and more fiber. At the time of this writing, there is no evidence to support risk or safety of certain foods with regard to postprandial hyperkalemia, and additional research is warranted.

Response to "Plant-based diets and postprandial hyperkalemia"

Diet therapy for hyperkalemia in people with chronic kidney disease (CKD) has shifted considerably in recent years with the observations that reported potassium intake is weakly, or not at all, associated with plasma potassium levels in this population. One of the lingering debates is whether dietary potassium presents a risk of hyperkalemia in the postprandial state. Although there is general agreement about the need for additional research, the commentary by Varshney et al contends that the available research sufficiently demonstrates that high-potassium plant foods do not pose a risk of postprandial hyperkalemia. Others argue that this remains unsettled science. Although the traditional approach of providing people with CKD lists of high-potassium foods to limit or avoid may be unnecessary, those at high risk of hyperkalemia should be encouraged to consume balanced meals and control portions, at least until some of the key research gaps in this area are resolved. This editorial critiques the analyses offered by Varshney et al and explains the rationale for a more cautious approach to care.

Hyperparathyroidism, Serum Phosphorus and Dietary Intake in Hemodialysis Patients: Is There a Novel Relationship?

The management of hyperparathyroidism (intact parathyroid hormone (iPTH) serum levels > 585 pg/mL), frequently focuses on the appropriate control of mineral and bone markers, with the decrease in serum and dietary phosphorus as two of the targets. We aimed to investigate the association between iPTH, serum phosphorus levels and dietary intake. This was a cross-sectional, multicenter, observational study with 561 patients on hemodialysis treatment. Clinical parameters, body composition and dietary intake were assessed. For the analysis, patients were divided into three groups: (a) iPTH < 130, (b) iPTH between 130 and 585 and (c) iPTH > 585 pg/mL. The association between PTH, serum phosphorus and dietary intake was analyzed using linear regression models. In the whole sample, 23.2% of patients presented an iPTH > 585 pg/mL. Patients with higher iPTH levels were those with longer HD vintage and lower ages, higher serum phosphorus, serum calcium, Ca/P product, albumin and caffeine intake, and a lower dietary intake of phosphorus, fiber, riboflavin and folate. Higher serum phosphorus predicted higher iPTH levels, even in the adjusted model. However, lower dietary phosphorus and fiber intake were predictors of higher iPTH levels, including in the adjusted model. Our results bring new data to the relationship between dietary intake and iPTH values. Despite higher serum phosphorus being observed in patients with HPTH, an opposite association was noted regarding dietary phosphate and fiber.

Hyperkalemia and Plant-Based Diets in Chronic Kidney Disease

Traditional dietary guidelines for patients with kidney disease recommend restriction of plant foods due to concerns about hyperkalemia and associated adverse events. Studies conducted over several decades have shown that the basis for these guidelines does not match the evidence. Serum potassium levels can be elevated in patients with reduced kidney function after consumption of foods with potassium-based additives or with highly concentrated potassium content such as juices, dried fruit, or purees. However, plant foods may have certain qualities that may blunt potassium retention including their alkalinizing effects, the lack of bioavailable potassium, and the impact of dietary fiber in organic plant foods on colonic potassium excretion. Furthermore, there are many benefits of plant foods that patients with kidney disease may be missing by excluding them from their diets by recommending the historical low-potassium "renal diet." Revised dietary recommendations for kidney health may encourage patient-centered kidney recipes that revolve around plant foods and do not restrict them.

A non-linear positive relationship between serum phosphate and clinical outcomes in sepsis

OBJECTIVE

This study aimed to evaluate the possible relationship between serum phosphate and short-term outcomes in sepsis.

METHODS

This was a retrospective study. Sepsis patients in MIMIC-IV database were included. Based on the quartiles of serum phosphate, all sepsis patients were divided into four groups. Univariable and multivariable regression analyses were constructed for discussing the relationship between different parameters and 30-day mortality in sepsis. A generalized additive model was performed for exploring the association of serum phosphate with 30-day mortality.

RESULTS

6251 sepsis patients including 4368 survivors and 1883 non-survivors were included. A significant relationship between serum phosphate and 30-day mortality was found after adjusting for all potential confounders (OR = 1.19, 95%CI:1.13-1.26, P < 0.0001). The relationship was non-linear with an inflection point of 6.8 mg/dl. On the left side of the inflection point (≤6.8 mg/dl, n = 5911 (94.56%)), the OR was 1.24 (95%CI: 1.17-1.31, P < 0.0001). On the right side of the inflection point (>6.8 mg/dl, n = 340 (5.44%)), the OR was 0.94 (95%CI:0.78-1.13, P = 0.5038).

CONCLUSION

A non-linear positive relationship was found between serum phosphate and 30-day mortality in sepsis. Serum phosphate was associated with mortality in sepsis. Our results could be used for screening out those sepsis patients with higher risk of worse outcomes.