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RJL Systems released version 4.1 of BC (Body Composition) on September, 28, 2015

If you downloaded the software from our website or purchased an analyzer in the last few weeks, you may already have BC 4.1. If you currently have a licensed copy of BC 4.0, version 4.1 is a free upgrade.

To check your version on Windows, launch BC and select “About” from the “Help” menu at the top of the window. On Mac OS, start BC, make sure it is the currently active window, and “About” will be under the “BC” menu in the menu bar at the top of the screen.

There are two main areas where we improved the program:

  • The “Person List” screen has received two major enhancements:
    1. Clicking on a column header in the list of people in the database now sorts the table on that column. Clicking on the header of the current sort column reverses the sort order.
    2. In addition to being able to search the database for people based on their name and Subject ID, you can also search for people tested on a specific date. You can also combine the search criteria, so you could search for people with first initial ‘J’, last initial ‘D’, who were tested on October 15, 2015.
  • We have added the ability to calculate Bone Mineral Content two different ways — what we’re calling the “Indirect” / “Old” method and the “Direct” / “New” method. In addition to setting this as a global default, the equation you choose gets saved to the person’s test records, just like all of the other equation selections.

The change in Item 2 requires some explanation. When RJL was doing research into new equations to add to BC 4.0, we developed new formulas for estimating Fat, Fat-Free Mass (FFM), Skeletal Muscle Mass (SMM), and Lean Soft Tissue (LST). We used the definition that Lean Soft Tissue was “the portion of Fat-Free Mass that is not Bone Mineral Content (BMC)” to estimate BMC by subtracting LST from FFM. Together, these equations formed the basis of the new “RJL Systems” equation set. Because these equations were developed at the same time from the same collection of data, they worked well together.

To allow you to estimate SMM, LST, and BMC using the older equation sets, we added the newly developed equations for SMM and LST to the existing equation sets, and BMC continued to be calculated by subtracting LST from the estimated FFM.

Each equation set has its own formula for FFM which came from a different study with a different population and different methods, the estimate it produces can vary. In some cases, the estimate for FFM produced by one of the existing equation sets can be less than the LST estimate produced by our new equation. When that happens, subtracting them results in a negative estimate for BMC, and the BC program will display a message saying “One or more calculated results is invalid.”

For perspective, the average adult man in the United States has only 2.7 kg (5.9 lbs) of mineral deposits in his bones. The average adult woman only has 2.1 kg (4.6 lbs). [*] Using this indirect method of estimating BMC by subtraction, the selected equation set’s estimate for FFM does not have to differ by much from RJL’s new equation to produce this condition.

To eliminate this issue, RJL has added a new equation that estimates BMC directly. When using this new direct method of calculating BMC, LST is calculated by subtraction.

When you launch BC for the first time after upgrading to version 4.1, you will be presented with a dialog box asking which method for calculating BMC you wish to use by default. We recommend that you select the new “direct” method. When it opens your database, it will ask if you want to update all of your existing test records to use the direct method, to leave them on the old, “indirect” method, or to ask you which one to use for each person. We recommend that you answer “direct” here, as well.

PLEASE NOTE: Changing existing tests to use the direct formula and reprinting the report will result in different BMC and LST estimates than were previously reported.

[*] Total Body Bone Area, Bone Mineral Content, and Bone Mineral Density for Individuals Aged 8 Years and Over: United States, 1999–2006
http://www.cdc.gov/nchs/data/series/sr_11/sr11_253.pdf

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