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In ideal situation, calcium adj equation is better derived from your methods and your population. This paper below and a work that we have published ( July 2012, annals) about calcium equation in children, showed a significant difference in slope and intercept with different population and methodologies ( Ca and alb). Barth JH, Fiddy JB, Payne RB. Adjustment of serum calcium for albumin concentration: effects of non-linearity and of regression differences between laboratories. Ann Clin Biochem 1996; 33:55-8. The last work has been done, showed that Ca Adj equation is also age dependent and the elderly population have a different equation compared the younger population. Best regards Nudar Consultant Clinical Biochemist From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Mohammad Al-Jubouri Sent: 22 November 2012 16:45 To: [log in to unmask] Subject: Re: Ionised calcium in ICU Hi Jonathan, We use CPC method on advia 2400 and we have a historical correction equation: - If albumin is 40 - 45, no correction is required and measured = adjusted. - if albumin < 40, then Adj calcium = measured Ca + (40 - albumin)*0.02 - if albumin > 45, then Adj calcium = measured Ca - (albumin - 40)*0.02 Our external QC for calcium is good. Brian Payne has kindly suggested that using ionised calcium in hypoalbuminaemic patients can give rise to falsely low results, so worth looking into his paper. Regards Mohammad From: Jonathan Kay <[log in to unmask]> To: Mohammad Al-Jubouri <[log in to unmask]> Cc: Jonathan Kay <[log in to unmask]>; "<[log in to unmask]>" <[log in to unmask]> Sent: Thursday, November 22, 2012 12:33 PM Subject: Re: Ionised calcium in ICU What algorithm do you use to calculate "adjusted calcium"? What method do you use to measure albumin? How well do those two work together? Jonathan On 22 Nov 2012, at 12:29, Mohammad Al-Jubouri wrote: Dear All, We only measure total calcium reported as adjusted calcium on ICU patients and a significant number have low results. An ICU calcium replacement protocol is instigated, however the calcium result remains low. Now ICU wants ionised calcium added to their blood gas machine for monitoring calcium status of their patients. Any words of wisdom on the clinical usefulness of inoised calcium in this setting is welcome. Many thanks Mohammad Dr. M A Al-Jubouri, MB ChB, MSc, FRCP Edin, FRCPath Consultant Chemical Pathologist ------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk/ Green Laboratories Work http://www.laboratorymedicine.nhs.uk/ List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/ ------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk Green Laboratories Work http://www.laboratorymedicine.nhs.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/ ------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk Green Laboratories Work http://www.laboratorymedicine.nhs.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/