2025 Hypophosphatemia Case Study

Hypophosphatemia in Home Parenteral Nutrition Patients Following Ferric Carboxymaltose Injection: A Case Series Review

Authors: Dana Finke, MS, RD, CNSC; Christine Miller, PharmD; Jessica Younkman, RD, CNSC; Paige Paswaters, RD, CNSC

Background and Purpose

• Iron deficiency anemia is common in patients receiving home parenteral nutrition (HPN).¹
• Post iron infusion, hypophosphatemia due to fibroblast growth factor 23 is a known side effect of some IV iron formulations.²
• Ferric carboxymaltose can cause serum phosphorus levels to drop below 2 mg/dL in 27% of patients.³
• Hypophosphatemia (<2.7 mg/dL) can lead to neurological, neuromuscular, cardiopulmonary, and hematologic issues, and long-term effects like osteopenia and osteoporosis.⁴
• Goal: Review the occurrence and clinical implications of transient serum phosphorus drops in patients receiving ferric carboxymaltose alongside HPN.
• Focus: Determine the impact on phosphorus levels and how interventions affect outcomes.

Methods

• A retrospective case series review was performed for three patients who were administered ferric carboxymaltose while receiving HPN therapy.
• Serum phosphorus levels were measured at baseline prior to initial iron dose, within 1 week post iron injection, and at subsequent time intervals up to 4 months post initial injection.
• Data was collected on the timing, magnitude, and duration of any phosphorus decreases, and any associated clinical symptoms or complications.
• Patient records were also reviewed to evaluate any correlations with HPN composition or phosphorus dosing.

Results

• Three patients receiving multiple doses of ferric carboxymaltose while on HPN were reviewed.
• Baseline phosphorus levels were normal in all cases.
• Average phosphorus drop: 50.3% from baseline to lowest level following ferric carboxymaltose dosing.
• Lowest phosphorus level recorded: 1.4 mg/dL.
• Interventions:
  • In two cases, HPN phosphorus levels were increased.
  • In one case, no changes were made, but levels normalized without intervention.
• Despite low phosphorus levels, no significant symptoms of hypophosphatemia were reported.

Discussion

• The findings from this case series underscore the significant impact of ferric carboxymaltose injections on serum phosphorus levels in patients receiving HPN. Consistent with existing literature, all three patients experienced transient drops in serum phosphorus levels following ferric carboxymaltose administration. This aligns with clinical trial data indicating that ferric carboxymaltose can cause hypophosphatemia in a substantial proportion of patients. The observed drops in phosphorus levels highlight the need for vigilant monitoring of serum phosphorus in patients receiving ferric carboxymaltose.
• Patients receiving HPN are closely monitored by a trained nutrition support team with frequent lab monitoring. Lab monitoring in patients receiving ferric carboxymaltose who are not on HPN may be less common. The lowest recorded phosphorus level of 1.4 mg/dL in one patient emphasizes the potential severity of this side effect.
• Despite the significant drops, it is noteworthy that none of the patients exhibited clinical symptoms of hypophosphatemia, suggesting that subclinical hypophosphatemia may be more common than symptomatic cases. In two of the reviewed cases, hypophosphatemia was addressed by making incremental increases in the patient’s HPN formulas.
• Note that there are limitations to phosphorus management in HPN due to compatibility and stability issues, and alternative means of supplementation may be necessary depending upon the patient’s individual formula.

Conclusion

• Three patients receiving HPN experienced transient drops in phosphorus levels after ferric carboxymaltose.
• Clinical complications were rare, and most phosphorus levels self-corrected over time.
• Recommendations: Monitoring of serum phosphorus and symptoms of hypophosphatemia are essential, with adjustments to HPN or phosphorus supplementation as needed.