Changes in bone mineral density in women following 1-year gastric bypass surgery.
BACKGROUND
Roux-en-Y gastric bypass (RYGB) surgery is the gold standard surgical treatment for obesity. However, unintended nutritional deficiencies following this surgery are common, including changes in bone metabolism. We assessed changes in bone mineral density (BMD), nutritional compounds, and bone resorption markers before and 1 year following RYGB surgery.


METHODS
Our study included 22 female patients with class II/III obesity. A clinical questionnaire, a 24-h recall, blood and urine samples, and dual-energy X-ray absorptiometry were provided.


RESULTS
Mean age was 37.2 ± 9.6 years; 86 % were Caucasian and 77.2 % were premenopausal. Mean preoperative body mass index was 44.4 ± 5.0 and 27.5 ± 4.5 kg/m(2) at 1-year follow-up (p < 0.001). 25-OH-vitamin D-levels were similar in both periods [11.7 (9.7-18.0) vs. 15.7 (10.2-2.7) pg/dL, p = 0.327]. Serum N-telopeptide (16.3 ± 3.4 vs. 38.2 ± 7.0 nM BCE, p < 0.001) and parathyroid hormone (45.4 ± 16.7 vs. 62.7 ± 28.9 pg/mL, p = 0.026) increased after RYGB surgery, reflecting bone resorption. BMD decreased after RYGB surgery in the lumbar spine (1.13 ± 0.11 vs. 1.04 ± 0.09 g/cm(2), p = 0.001), femoral neck (1.03 ± 0.15 vs. 0.94 ± 0.16 g/cm(2), p = 0.001), and total femur (1.07 ± 0.11 vs. 0.97 ± 0.15 g/cm(2), p = 0.003).


CONCLUSIONS
Decreased BMD in the lumbar spine, femoral neck, and total femur is detectable in women 1 year after RYGB surgery. Calcium malabsorption, caused by vitamin D deficiency and increased bone resorption, is partially responsible for these outcomes and should be targeted in future clinical trials.
Postgraduate Program in Medical Sciences: Endocrinology and Metabolism, Hospital de Clinicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Daniela Schaan
DS
Casagrande
Giuseppe
G
Repetto
Claudio Corá
CC
Mottin
Jatin
J
Shah
Ricardo
R
Pietrobon
Mathias
M
Worni
Beatriz D
BD
Schaan
D015502:Absorptiometry, Photon; D000328:Adult; D015992:Body Mass Index; D015519:Bone Density; D001862:Bone Resorption / Q000000981:diagnostic imaging / Q000378:metabolism*; D001938:Brazil; D002136:Calcium, Dietary / Q000378:metabolism; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000378:metabolism*; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000009:adverse effects / Q000379:methods; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism*; D009767:Obesity, Morbid / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000601:surgery; D017697:Premenopause; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014808:Vitamin D Deficiency / Q000378:metabolism*; D015431:Weight Loss
D002136:Calcium, Dietary