Bsm1 Vitamin D Receptor Polymorphism and Calcium Homeostasis Following Bariatric Surgery

ABSTRACT

Purpose/Aim: To evaluate the association between the Bsm1 vitamin D receptor polymorphism and the calcium-vitamin D-parathormone axis following bariatric surgery. Materials and Methods: This cross-sectional study included 86 morbidly obese patients, who underwent either gastric bypass or sleeve gastrectomy, with a mean follow-up of four years. Calcium metabolism indices and bone turnover markers were assessed according to the presence of secondary hyperparathyroidism and the Bsm1 vitamin D receptor genotypes. Results: Secondary hyperparathyroidism (42.2% of sample) was associated with lower levels of 25hydroxyvitamin D and elevated markers of bone turnover. In subjects without secondary hyperparathyroidism, presence of the unfavorable B allele resulted in higher levels of parathormone (Bb and BB vs. bb genotype: 50.3 ± 8.2 pg/dl vs. 44.4 ± 10.7 pg/dl, p = .011, adjusted for weight loss, baseline body mass index, 25hydroxyvitamin D, surgical procedure, and duration after surgery). In the whole sample, patients bearing the unfavorable B allele exhibited lower weight loss, a parameter that was negatively associated with markers of bone resorption. Conclusions: Secondary hyperparathyroidism is highly prevalent after bariatric surgery. Bsm1 vitamin D receptor polymorphism may have an effect in early stages of calcium metabolism imbalance, while no association is detected in patients who have already developed secondary hyperparathyroidism. Moreover, vitamin D receptor polymorphism is associated with post-surgery weight loss, a process related to bone turnover.

Keywords: :

• Bsm1 VDR polymorphism
• parathormone
• calcium metabolism
• bariatric surgery
• Roux-en-Y Gastric bypass
• sleeve gastrectomy

SUPPLEMENTARY MATERIAL

Questionnaire

Evaluation of demographic and lifestyle parameters.

1. Race

   (0: Caucasian, 1: Non-Caucasian)

2. Ethnicity

   (0: Greek, 1: Other)

3. Type of surgery

   (0: Roux-En-Y-Gastric Bypass, 1: Sleeve Gastrectomy)

4. Gender (0: male, 1: female)

5. Date of birth

6. Marital status

   (0: married, 1: single/divorced/widowed)

7. Highest degree obtained

   (0: no education, 1: primary education, 2: secondary education, 3: university degree)

8. Physical exercise

   (0: not at all, 1: ≤ 1 hr weekly, 2: 1–4 hr weekly,

   3: > 3 hr per week)

9. Alcohol consumption

   (0: never, 1: occasionally, 2: daily)

10. Smoking habits

    (0: never or past smoker, 1: current smoker)

11. Medical history:

    (0: no, 1: yes)

  • Diabetes mellitus?

  • Hypertension?

  • Coronary heart disease?

  • Dyslipidemia

  • Arterial thrombosis

  • Thromboembolism

  • Thyroid dysfunction

  • Other (specify)

12. Medication administration (0: no, 1: yes)

  • Oral hypoglycemic drugs (metformin, sulfonylureas, a-glycosidase inhibitors, DPP4, GLP-1)

  • Insulin (glargine, levemir, or human isophane insulin)

  • Angiotensin II receptor antagonist

  • Calcium channel blocker

  • Diuretic

  • B-Blocker

  • Digoxin

  • Hypolipidemic drugs: statins, fibrates, nicotinic acid

  • Acenocoumarol

  • Heparin

  • Levothyroxine

  • Antithyroid drugs: carbimazole, thiamazole

  • NSAIDs

13. vitamin and micronutrient supplementation (0: no, 1: yes)

  • Calcium and vitamin D

  • Ferrum

  • Folic acid

  • Vitamin B12

  • Multivitamins

14. Menopausal status (for women)

  (0: premenopausal, 1: postmenopausal)

15. For women: Years since menopause