Pseudo-hypophosphatemia

Q: Intravenous (IV) mannitol may cause? - select one

A) pseudo-hypocalcemia 

B) pseudo-hypokalemia

C) pseudo-hypomagnesemia

D) pseudo-hyponatremia

E) pseudo-hypophosphatemia

Answer: E

The first step in the evaluation of pseudohypophosphatemia is to rule out spurious or pseudo-hypophosphatemia. Many well-known conditions and drugs may cause pseudohypophosphatemia either by the presence of paraproteins or by interference with the phosphate assay. Some of the causes are:

• multiple myeloma 
• other monoclonal gammopathies
• IV mannitol (usually in large or repeated doses)

#electrolytes

References:

1. Molinaris V, Bianchetti MG, Milani GP, et al. Interferences in the measurement of circulating phosphate: a literature review. Clin Chem Lab Med 2020; 58:1971.

2. Kerr S, Kindt J, Daram SR. Hypophosphatemia associated with paraproteinemia: a case report and review of the literature. WMJ 2007; 106:490.

3. Wen Wu L, Choi TS, Barbosa M, et al. PSEUDOHYPOPHOSPHATEMIA IN A PATIENT WITH MULTIPLE MYELOMA. AACE Clin Case Rep 2020; 6:e334.

4. Larner AJ. Pseudohyperphosphatemia. Clin Biochem. 1995 Aug;28(4):391-3. doi: 10.1016/0009-9120(95)00013-y. PMID: 8521592.