Albumin and electrolytes

Q: Hypoalbuminemia may cause false negative? (select one)

A) hypokalemia

B) hypomagnesemia

Answer: B

One caveat to measuring magnesium in chronically malnourished patients is knowing their magnesium level via regular tests. About 30% of magnesium is bound to albumin and is inactive. 

Hypoalbuminemia may cause spuriously low magnesium levels. There is no formula to adjust total and ionized magnesium. The ionized (free) magnesium level should be ordered via direct measurement.

#electrolytes

References:

1. Kroll MH, Elin RJ. Relationships between magnesium and protein concentrations in serum. Clin Chem. 1985 Feb;31(2):244-6. PMID: 3967355.

2. Huijgen HJ, Soesan M, Sanders R, Mairuhu WM, Kesecioglu J, Sanders GT. Magnesium levels in critically ill patients. What should we measure? Am J Clin Pathol. 2000 Nov;114(5):688-95. doi: 10.1309/jr9y-pptx-ajtc-qdrd. PMID: 11068541.

3. Xu B, Sun J, Deng X, Huang X, Sun W, Xu Y, Xu M, Lu J, Bi Y. Low serum magnesium level is associated with microalbuminuria in chinese diabetic patients. Int J Endocrinol. 2013;2013:580685. doi: 10.1155/2013/580685. Epub 2013 Aug 26. PMID: 24065990; PMCID: PMC3770069.