Vitamin D Deficiency Pre- and Post-Bariatric Surgery

Pre-Operative Period

Vitamin D is integral in maintaining normal calcium levels by aiding in absorption. Individuals who are obese have greater fat mass, so more vitamin D is required to maintain normal concentrations, due to the fact that vitamin D is segregated in adipose cells¹. Peterson et al. noted a deficiency rate of 71.4% out of 58 patients studied, with the majority of deficiency presenting in minority races. Melanin concentrations in the skin present as a risk factor for vitamin D deficiency, with increased concentrations providing a greater risk due to the fact that melanin inhibits vitamin D synthesis¹. Another study showed 89.7% of patients had 25-OH-D levels below 76.0 nmol/l, 61.2% below 50.0 nmol/l, and 25.4% below 25nmol/l. As BMI increased across the study population, the rate of vitamin D deficiencies also increased².

Post-Operative Period

There is evidence that suggests weight loss procedures can cause a negative effect on bone mineral density, accelerate bone loss, and increase bone fragility³. However, these negative effects can mostly be reversed with adequate supplementation after surgery⁴. Serum calcium levels often remain within normal limits in post-operative patients, due to the regulatory pathways in the body. Unfortunately, obese individuals typically have abnormal 25(OH)D levels due to sequestration of vitamin D within adipose tissue, as well as due to a sedentary lifestyle with reduced sunlight exposure⁴. It's believed that changes in gut hormone concentrations after the sleeve gastrectomy can cause vitamin D deficiency in post-operative patients⁵.

Lu et al. conducted a twelve-year study to observe fracture risk in bariatric surgery patients. Their results showed that out of the total 1,775 patients that had a restrictive procedure, 154 patients (8.7%) had fractures. The fracture rate for the surgical group were: 1.6% at 1 year, 2.37% at 2 years, 1.69% at 5 years, and 2.06% at greater than 5 years, with most fractures occurring in the extremities³.

Likewise, Mihmanli et al. studied 119 post-sleeve gastrectomy patients and their vitamin D levels during the first year after surgery. At 12 months post-surgery, 32.7% of patients needed high-dose vitamin D supplementation to combat deficiency⁵.

Carrasco et al. noted vitamin D deficiency in sleeve gastrectomy patients as being 31.6% pre-op, 5.6% at 6 months, and 15.8% at 12 months after surgery. Coincidentally, hyperparathyroidism was observed in 57.9% pre-op, 31.6% at 6 months, and 5.3% at 12 months post-surgery. Bariatric patients who achieved higher vitamin D and calcium intake via diet and supplementation had reduced parathyroid hormone levels. Calcium intake of patients, closer to ASMBS recommendations, showed an association with less bone loss in the lumbar region of the spinal cords of sleeve gastrectomy patients⁶.

Pluskiewicz et al. noted bone mineral density reductions of 1.2% in the spine, 7% in femoral neck, and 5.3% in total hip in sleeve gastrectomy patients 6 months post-surgery⁷. A review of evaluation and management of bone health in the surgical patient (Table 1) and recommendations for calcium and vitamin D supplementation (Table 2) are described below⁸

^{Table 1-Evaluation and Management of Bone Health in Surgical Patients}

Adapted from Ben-Porat T, Elazary R, Sherf-Dagan S, et al. Bone Health following Bariatric Surgery: Implications for Management Strategies to Attenuate Bone Loss. Adv Nutr. 2018;9(2):114‐127. doi:10.1093/advances/nmx024

Table 2- Recommendations for Calcium and Vitamin D Supplementation

Adapted from Ben-Porat T, Elazary R, Sherf-Dagan S, et al. Bone Health following Bariatric Surgery: Implications for Management Strategies to Attenuate Bone Loss. Adv Nutr. 2018;9(2):114‐127. doi:10.1093/advances/nmx024

References:

1. Peterson, L.A., Cheskin, L.J., Furtado, M. et al. Malnutrition in Bariatric Surgery Candidates: Multiple Micronutrient Deficiencies Prior to Surgery. OBES SURG 26, 833–838 (2016). https://doi.org/10.1007/s11695-015-1844-y
2. Ernst, B., Thurnheer, M., Schmid, S.M. et al. Evidence for the Necessity to Systematically Assess Micronutrient Status Prior to Bariatric Surgery. OBES SURG 19, 66–73 (2009). https://doi.org/10.1007/s11695-008-9545-4
3. Lu CW, Chang YK, Chang HH, et al. Fracture Risk After Bariatric Surgery: A 12-Year Nationwide Cohort Study. Medicine (Baltimore). 2015;94(48):e2087. doi:10.1097/MD.0000000000002087
4. Folli F, Sabowitz BN, Schwesinger W, Fanti P, Guardado-Mendoza R, Muscogiuri G. Bariatric surgery and bone disease: from clinical perspective to molecular insights. Int J Obes (Lond). 2012;36(11):1373‐1379. doi:10.1038/ijo.2012.115
5. Mihmanli M, Isil RG, Isil CT, et al. Effects of Laparoscopic Sleeve Gastrectomy on Parathyroid Hormone, Vitamin D, Calcium, Phosphorus, and Albumin Levels. Obes Surg. 2017;27(12):3149‐3155. doi:10.1007/s11695-017-2747-x
6. Carrasco F, Basfi-Fer K, Rojas P, et al. Changes in bone mineral density after sleeve gastrectomy or gastric bypass: relationships with variations in vitamin D, ghrelin, and adiponectin levels. Obes Surg. 2014;24(6):877‐884. doi:10.1007/s11695-014-1179-0
7. Pluskiewicz W, Buzga M, Holeczy P, Bortlik L, Smajstrla V, Adamczyk P. Bone mineral changes in spine and proximal femur in individual obese women after laparoscopic sleeve gastrectomy: a short-term study. Obes Surg 2012;22(7):1068–76
8. Ben-Porat T, Elazary R, Sherf-Dagan S, et al. Bone Health following Bariatric Surgery: Implications for Management Strategies to Attenuate Bone Loss. Adv Nutr. 2018;9(2):114‐127. doi:10.1093/advances/nmx024