Albumin-Ca connection

Q: In hyperalbuminemia ____________ is expected? (select one)

A) hypocalcemia

B) hypercalcemia

Answer: B

In hyperalbuminemia total serum calcium level is expected to be high due to the calcium-albumin binding situation. This is not real hypercalcemia as ionized calcium stays normal. This is called pseudo or factitious hypercalcemia.

About half of the calcium in serum is bound to albumin. The best to have a calcium level is to measure ionized calcium. Unfortunately, it may not be readily available. Formulae have been developed to adjust calcium per albumin level. As a rule of thumb, for every 1 g/dL drop in the serum albumin the serum calcium drops by 0.8 mg/dL.

#electrolytes

References:

1. Thode J, Juul-Jørgensen B, Bhatia HM, Kjaerulf-Nielsen M, Bartels PD, Fogh-Andersen N, Siggaard-Andersen O. Comparison of serum total calcium, albumin-corrected total calcium, and ionized calcium in 1213 patients with suspected calcium disorders. Scand J Clin Lab Invest. 1989 May;49(3):217-23. Erratum in: Scand J Clin Lab Invest 1990 Feb;50(1):113. PMID: 2662382.

2. Lian IA, Åsberg A. Should total calcium be adjusted for albumin? A retrospective observational study of laboratory data from central Norway. BMJ Open. 2018;8(4):e017703. Published 2018 Apr 7. doi:10.1136/bmjopen-2017-017703