Bone Health Is Affected By Amount of Weight Lost Following RYGB

Greater changes in body mass index (BMI) following Roux-en-Y gastric bypass (RYGB) are associated with lower bone mineral density (BMD) more than 9 years after the procedure, according to a recent study. Deficiencies in calcium and vitamin D may be to blame.

For their study, the researchers evaluated 51 participants who had received RYGB. Mean patient age was 17 years.
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Dietary calcium and protein were recorded, and dual-energy x-ray absorptiometry was used to assess BMD at the spine, hip, and radius. Routine serum chemistries, magnesium, phosphorous, parathyroid hormone, vitamin D, vitamin K, and micronutrients were assessed. Additionally, calcium levels were evaluated in 16 participants who provided 24-hour urine.

After more than 9 years, patients’ mean maximum weight loss had been approximately 155 lbs, and mean net weight loss had been about 103.4 lbs. Fractures had occurred in 15.7% of participants, secondary hyperparathyroidism had occurred in 37% of participants, and vitamin D deficiency had occurred in 39% of participants. The researchers also found that 27.5% of participants had demonstrated a BMD in the osteoporotic range.

The researchers also calculated patients’ mean calcium:creatinine clearance ratio as 0.0124, median intake of dietary calcium as 582.5 mg, total calcium intake as 947.5 mg, protein intake as 50.2 g, and vitamin D intake as 1000 IU.

Mean Z-scores at all sites had been less than 0, with a negative correlation observed between distal radius Z-score and net change in BMI. The net change in BMI had been greater among participants with osteoporosis vs those without osteoporosis.

“Many years after RYGB, BMD remains lower than expected compared to an age-, sex-, race-, and weight-matched reference population and is correlated with the amount of weight lost,” the researchers concluded. “Deficiencies of vitamin D and calcium are prevalent.”

—Christina Vogt

Reference:

Jackson Cook F, Khanna I, Giordano J, Matarese L, Hudson S. Long-term bone health after Roux-en-Y gastric bypass: a pilot study. Endocr Pract. 2017;23(9). https://doi.org/10.4158/EP171823.OR.