Assessment of Body Weight Change Patterns and Their Association With Serum Vitamin D and Parathyroid Hormone Levels Following Bariatric Surgery in Adolescents: A Longitudinal Study; [بررسی الگوی تغییر وزن بدن و ارتباط آن با وضعیت سرمی ویتامین دی و هورمون پاراتیروئید پس از جراحی چاقی در نوجوانان: یک مطالعه طولی]



Dianati Z ; Tabesh MR ; Khalaj A ; Honardoust M ; Asghari G
Source: Iranian Journal of Nutrition Sciences and Food Technology Published:2026

Abstract

Background and Objectives: Obesity is a complex chronic disease with rising prevalence, posing a significant public health concern among Iranian adolescents. In refractory cases, sleeve gastrectomy reduces weight but may alter body composition and disrupt vitamin D and parathyroid hormone homeostasis. This study examines these changes and their interrelationships in adolescents following bariatric surgery. Materials & Methods: This cohort study analyzed data from 50 adolescents aged 12 to 18 who underwent sleeve gastrectomy between 2015 and 2022. Weight, height, and body mass index (BMI) measurements, along with fasting blood sampling to determine vitamin D and parathyroid hormone (PTH) serum levels, were conducted preoperatively and subsequently at 3, 6, 12, 18, and 24 months post-operation. Statistical data analysis was performed using appropriate tests, including Spearman’s correlation coefficient. Results: Weight loss remained sustained up to 24 months; the only significant correlation between weight change and VITD was observed in females at month 3 (r = −0.516, p = 0.014), indicating that greater weight loss in females was associated with lower VITD levels; in males at month 24 a strong inverse correlation between VITD and PTH was found (r = −0.574, p = 0.001), with all other associations non-significant. Conclusion: Sleeve gastrectomy in adolescents led to significant and sustained weight loss up to 24 months. Nonetheless, fluctuating vitamin D levels and progressive increases in PTH underscore the need for periodic biochemical monitoring and targeted nutritional interventions to prevent bone and metabolic complications. © 2026, National Nutrition and Food Technology Research Institute. All rights reserved.