7 responses to “Correcting the Myth of Calcium Correction”

  1. Wow! This was very informative and what seems like an important new perspective to how calcium levels should be thought about and assessed. Thanks for writing this.

  2. Based on this evidence, I will abandon the Payne formula, and screen at low to moderate risk oncology patients with serum calcium and confirm with ionized calcium. I will order ionized calcium in high risk oncology patients.

  3. I love it when orthodoxy is questioned and found wanting. Thank you for updating our understanding of this aspect of calcium testing.

  4. although it is not applicable to my current practice , I found it very rational and useful and surly I will use this information in relevant discussions with my patients and other healthcare professionals.

  5. 1. Ref 15 is cited as the source for the statement “in hypoalbuminaemic states, the binding constant between albumin and calcium changes, and more calcium binds to each available gram of albumin.” Ref. 15 drew that conclusion from an inverse correlation they observed between the Calcium bound per g albumin (y axis) and albumin (x axis). Unfortunately, that correlation is statistically flawed because the measurements in the y-axis and x axis are not independent of each other (albumin appears in both). A negative correlation is tautologically inevitable and no inference can be drawn from it.

    2. Great review of the weakness of the albumin correction. Correcting total calcium for both (1) the complexation of calcium by anions and (2) binding of calcium to albumin might improve the estimation of ionized calcium, but there will always be incertitude. A new method that, instead, assesses the PROBABILITY of significant hypocalcemia, based on both those corrections using only routine data–and which was, at least, internally validated in a separate cohort–was recently published by me and my co-authors. We think it could help guide the decision to measure ionized calcium. A working calculator can be downloaded from the article’s supplemental appendix if anyone wishes to try it: http://jalm.aaccjnls.org/content/early/2019/10/18/jalm.2019.029314/tab-figures-data

  6. to Philip Goldwasser – the link you provided no longer works (it is now 2023). Is there a way you could provide a new link to your calculator?

  7. Thanks. A working link for the calculator I referenced above is now located at qxmd:

    Incidentally, this method underwent successful external validation twice recently:

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