PHOTO: Decades ago, every doctors' office regularly used a balance beam scale, similar to my bathroom mechanical balance beam weight scale that I've owned for twenty years and use to detect sudden weight loss due to medical reasons or from dieting. My bathroom scale is shown above, next to a stainless steel handicap grab bar I originally installed to be a towel bar because it looked better than the standard towel bars available back then, but today this "towel bar" also serves the more practical function of being something I can grab to steady myself and also a place I can hang up my low-vision support cane. See previous posts LED Pixi flat panel light replaces my laundry room light (4/10/15) and Wheelchair accessible Speed Queen Washer Dryer replaces old Maytag stacker (7/7/14)
As a kid, doctors would always make a big deal about how accurate their balance beam scales were compared to the typical home mechanical spring scales.
Therefore, I was surprised to see on my recent visits to several doctors' offices that they had replaced their mechanical balance beam scales with electronic stain-gauge scales with large digital readings on LCD displays. None of them had any visible source of calibration, nor did any doctor seem to be concerned about their absolute accuracy because human weight can easily vary by pounds within a few hours for many individuals and doctors are mostly interested in relatively large changes in weight over a period of time.
The advantages of mechanical balance beam scales are they don't require any power or batteries, which makes them electrically safe in a medical environment, and they also don't require any regular maintenance, other than perhaps lubricating and periodic replacement when the mechanism wears out, which may the reason why they have disappeared from my doctors' offices where weight scales get constant use.