Pretreatment of enteral nutrition with sodium polystyrene sulfonate: effective, but beware the high prevalence of electrolyte derangements in clinical practice

Abstract

BackgroundCurrent treatment options for chronic hyperkalemia in children with chronic kidney disease include dietary restrictions or enteral sodium polystyrene sulfonate (SPS); however, dietary restrictions may compromise adequate nutrition and enteral SPS may be limited by palatability, adverse effects and feeding tube obstruction. A potentially safer alternative is to pretreat enteral nutrition (EN) with SPS prior to consumption. The purpose of this study was to evaluate the efficacy and safety of pretreating EN with SPS in pediatric patients with hyperkalemia.MethodsWe performed a retrospective cohort study between September 2012 and May 2016 at the Children’s Hospital of Philadelphia. In all, 14 patients (age range 0.5–53.2 months) who received 19 courses of SPS pretreatment of EN were evaluated. Serum electrolytes were evaluated at baseline and within 1 week of initiating therapy. The primary endpoint was mean change in potassium at 7 days. Secondary endpoints included the mean change in serum sodium, chloride, bicarbonate, calcium, phosphorous and magnesium, as well as the percentage of patients who developed electrolyte abnormalities within the first week of treatment.ResultsSerum potassium levels decreased from 6.0 to 4.4 mmol/L (P < 0.001) and serum sodium levels increased from 135.8 to 141.3 mmol/L (P = 0.008) 1 week after initiating SPS pretreatment. No significant differences in mean serum calcium or magnesium levels were noted. Nevertheless, more than half of the courses resulted in at least one electrolyte abnormality, with hypokalemia (31.6%), hypernatremia (26.3%) and hypocalcemia (21.1%) occurring most frequently.ConclusionsPretreatment of EN with SPS is an effective method for treating chronic hyperkalemia in pediatric patients; however, close monitoring of electrolytes is warranted.

Let food be thy medicine and medicine be thy food?

“…The preparation and method of pretreatment of enteral nutrition with SPS had a similar methodology compared with other studies, so does not explain the in vivo and in vitro differences. Independent of potassium, sodium and calcium, Palma et al [ 18 ] found no significant difference in bicarbonate or chloride levels, which is consistent with the previous in vivo study by Thompson et al [ 12 ]. However, as demonstrated in other studies (see Table 1 ) [ 11 , 15 , 16 ], due to the non-specific binding nature of SPS, there may be significant, yet inconsistent effects on other essential trace elements such as zinc, copper and manganese.…”

“…The rates of clinical hypokalaemia (31.6%) and hypernatraemia (26.3%) described by Palma et al [ 18 ] mimic the in vitro findings on the potassium and sodium content of feeds following pretreatment with SPS [ 10–17 ], although the degree of electrolyte disturbance is less marked. For example, clinical hypernatraemia developed following SPS pretreatment in only five cases (26.3%), despite the reported increase in in vitro studies of sodium feed content by 86–527% [ 10 , 11 , 13–17 ].…”

“…For example, clinical hypernatraemia developed following SPS pretreatment in only five cases (26.3%), despite the reported increase in in vitro studies of sodium feed content by 86–527% [ 10 , 11 , 13–17 ]. Most in vitro studies also demonstrate a reduction in feed calcium content following pretreatment with SPS (range 8–84%) [ 10 , 11 , 14 , 15 , 17 ], contributing to the reported incidence of episodic hypocalcaemia seen by Palma et al [ 18 ] in four cases (21.1%). The impact on ionized calcium, a more relevant in vitro measurement, remains unknown.…”

“…The gastrointestinal disturbances and hypocalcaemia described in the first case are similar to case reports elsewhere: Kakajiwala et al [ 20 ] describe two cases of hypocalcaemia and metabolic alkalosis attributed to the use of SPS, where one child was receiving pretreated formula. In the second case of potentially life-threatening adverse events described by Palma et al [ 18 ], although causation cannot be certain due to other comorbidities, clinicians must be aware that the addition of SPS to feeds is not a benign or risk-free intervention. Furthermore, these events occurred with correct preparation and pretreatment in a hospital environment.…”

Optimizing Enteral Nutrition for Growth in Pediatric Chronic Kidney Disease (CKD)

“…Thus, if this product is used, the powdered version should be chosen. Although considered to be safer than oral or rectal administration, there are still risks with the decanting process, including common risks of serious biochemical derangement (67) as it is not possible to remove all of the SPS solution from the decanted formula.…”