Update on Stopping Strontium before Total Calcium Test

I just got my latest total calcium results. I stopped taking strontium citrate for 17 days prior to my blood collection date of 11/13/2014. My result was 9.8 mg/dL, with a reference range of 8.5 to 10.5 mg/dL.

I began stopping the strontium for several days prior to blood draws as of 07/24/2012. I also switched laboratories on that date. My calcium results have all been normal. The 10.3 result of 07/24/2012 was high normal, according to the reference range for the new laboratory.

Collection Date     Stopped Strontium?          Total Calcium           Ref. Range

11/13/2014            Yes, 17 days before test          9.8                     8.5-10.5

11/12/2013            Yes, 12 days before test           9.5                    8.5-10.5 

07/24/2012            Yes, 11 days before test         10.3                    8.5-10.5

Prior to 07/24/2012, I was either not stopping my strontium or stopping just a day before blood collection. I had one high calcium result on 12/28/2009 (10.3 with reference range of 8.6-10.2 mg/dL). You will note all these earlier calcium tests were done at a different laboratory, with a different reference range.

Collection Date     Stopped Strontium?          Total Calcium           Ref. Range
12/09/2010            Yes, night before test               9.8                     8.6-10.2

12/28/2009                       No                                10.3 H                8.6-10.2

03/19/2009                       No                                   9.7                   8.6-10.2

01/06/2009                       No                                10.1                    8.6-10.2

The reason for stopping strontium for at least 12 days prior to blood or urine collection for calcium:

I have read that strontium reaches peak blood levels in 12 days of strontium intake. Servier, the manufacturer of strontium ranelate, has stated that sr. ranelate interferes with colorimetric tests for calcium. Automated total serum calcium tests are colorimetric. Urine calcium tests are usually colorimetric. If you stop taking strontium for 12 days or more, your blood level should be significantly lower than peak level. Therefore, it may be a good idea to stop taking strontium 12-14 days prior to having blood drawn for a total serum calcium and prior to collecting urine for a urine calcium test. Urine calcium values may vary considerably and are only meaningful if the patient is kept on a low-calcium, neutral-ash diet for three days before collection.

I’m not sure if stopping strontium citrate prior to specimen collection for calcium tests has made a difference for me or not, but I want to avoid another high calcium result. I have had one, and it was most likely falsely elevated by strontium.