We are often asked whether or not serum magnesium is a good indicator of magnesium deficiency as many of you have been told that RBC magnesium is the gold-standard. Dr. Weatherby had a conversation with Dr. Kevin Bodling of Evexia Diagnostics and here is Dr. Bodling's response to this question:
I agree and concede that RBC magnesium is theoretically the best way to assess magnesium status. However, the point I wanted to make to you was that the lab reference range is really too broad on the RBCMagnesiumto catch a lot of clinically sub-optimal magnesium deficiencies. In addition, there really isn’t any established “optimal range” for RBC magnesium. So, based on the thousands of case studies I have personally performed and even compared to intracellular tests such as the Spectracell micronutrient testing, the optimal range set for serum magnesium is actually superior and will give you a much better indication of any slight deficiencies in magnesium. Furthermore, since B1 deficiencies often accompany magnesium deficiencies, you are likely to miss both if you only use the RBC magnesium and the associated lab reference range.
Given that, we now have both Serum and RBC magnesium built into the software so feel free to choose which one works for your patient.