Pseudohyperphosphatemia induced by endogenous lipoproteins: New elements supporting an interference with ammonium
Charles R Lefèvre1,2, Felipe Le Divenah1, Bastien Paterek1
1Clinical Biochemistry and Toxicology Laboratory, Rennes University Hospital Centre, Rennes, France.
Annals of Clinical Biochemistry
|April 29, 2025
Summary
Hyperlipidemia can falsely elevate inorganic phosphate (Pi) levels, a condition known as pseudohyperphosphatemia. This study confirms this interference is dependent on lipemia levels.
Area of Science:
- Clinical Chemistry
- Biochemistry
- Medical Diagnostics
Background:
- Inorganic phosphate (Pi) is vital for homeostasis.
- Standard Pi measurement methods use acidic conditions, which can interfere with certain substances.
- Previous studies noted phospholipid interference; this study investigates endogenous lipoproteins.
Purpose of the Study:
- To determine if endogenous lipoproteins in hyperlipidemia interfere with inorganic phosphate (Pi) measurement.
- To quantify the impact of lipemia on Pi levels.
Main Methods:
- Retrospective analysis of Pi levels in 194,636 patients across varying lipemia degrees.
- Prospective study of 85 patients evaluating Pi levels before and after plasma filtration to remove lipoproteins.
Main Results:
- Retrospective data showed a significant Pi increase with higher lipemia (P < .0001).
- Prospective study: Pi levels decreased by 6.8% after filtration (1.36 vs. 1.27 mmol/L, P < .0001).
- The bias in Pi measurement correlated with lipemia levels (r = 0.34, P = .001).
Conclusions:
- Hyperlipidemia causes analytically significant pseudohyperphosphatemia.
- The degree of lipemia directly influences the accuracy of Pi measurements.
- This interference must be considered in clinical diagnostics for hyperlipidemic patients.
