Introduction

Patients with inflammatory bowel disease (IBD) are at increased risk of reduced bone mineral density (BMD), often linked to chronic inflammation, corticosteroid use, biologics, and vitamin D deficiency. 25-hydroxyvitamin D (25(OH)D) is a fat-soluble vitamin essential for calcium and phosphorus homeostasis, and its deficiency is common in IBD due to malabsorption, dietary, altered metabolism, or impaired VDR signaling.

Aims & Methods

This cross-sectional study aimed to evaluate the relationship between serum 25(OH)D levels, BMD, and body composition in IBD patients. A total of 73 outpatients with IBD (38 ulcerative colitis, 35 Crohn’s disease) were assessed. Body composition was evaluated using BMI and bioelectrical impedance analysis (BIA). BMD was measured using whole-body dual-energy X-ray absorptiometry (DEXA), and vitamin D status was assessed by serum 25(OH)D concentration. Statistical analysis included descriptive and comparative tests (Chi-square and t-test).

Results

Participants had a mean age of 45.27±11.37 years, with 67.1% being female and a mean disease duration of 10.22±7.54 years. Most patients (93.15%) were in clinical and endoscopic remission. The average BMI was 26.85±4.51 kg/m², with 39.7% classified as overweight. DEXA revealed a high prevalence of osteopenia (39.7%) and osteoporosis (19.0%). Mean BMD Z-scores were whole body -1.32±1.13, spine -0.92±1.19, and femoral neck -0.34±1.02. Mean serum 25(OH)D level was 31.20±8.78 ng/mL; 52.1% had insufficient levels and 47.9% were sufficient. Vitamin D insufficiency was significantly associated with osteopenia/osteoporosis (p=0.0144) and with overweight/obesity (p=0.0265). No significant associations were observed between vitamin D levels and age (p=0.6476), sex (p=0.4565), lean mass (p=0.2941), fat mass (p=0.1218), phase angle (p=0.3154), or regional BMD (total body p=0.5001; spine p=0.3067; femoral neck p=0.2364).

Conclusion

IBD patients are vulnerable to low serum vitamin D levels and present a high prevalence of low BMD. Vitamin D insufficiency was associated with altered BMI and increased risk of osteopenia/osteoporosis, though not with other body composition metrics. Further studies are needed with larger and more clinically heterogeneous samples to confirm these associations and guide screening and supplementation strategies.

References

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Clinical Case Summary

Case: A 23-year-old female patient presented with non-bloody diarrhea, abdominal pain, flatulence, postprandial fullness, bloating, nausea, anal pain and itching, and low back pain. Three years prior, a minor trauma led to an X-ray revealing a compression fracture of two lumbar vertebrae. A densitometric exam of bone tissue showed osteopenia (T-score = -1.2). The patient reported no harmful habits and no relevant family medical history. Physical exam revealed abdominal tenderness in the right and left pelvic regions. Laboratory abnormalities included CRP at 6.78 mg/L, fecal calprotectin >1000 µg/g, total IgA at 1.91 g/L, and Anti-tTG IgA at 406.1 RU/mL. Tests for intestinal infections were negative. An abdominal CT scan revealed terminal ileitis with mesenteric lymphadenopathy. Endoscopy showed multiple erosive lesions in the stomach (Helicobacter pylori negative), as well as multiple erosive lesions with fibrin coating in the ileum. Isolated erosive lesions were also noted in the transverse, descending, and sigmoid colons, and the lower ampullary section of the rectum. Histological patterns were consistent with both Crohn's disease (Montreal classification: A2, L3 + L4, B1p) and Celiac disease (Marsh classification: III B). The therapeutic approach was tailored to the patient’s condition: biological therapy (Infliximab), a gluten-free diet, bisphosphonates, calcium, and vitamin D supplementation.
Conclusion: Both Crohn’s and Celiac disease are primarily considered gastrointestinal (GI) disorders, but they are systemic conditions that may present with a broad range of extraintestinal manifestations. These may develop earlier than, or in the absence of, classic GI symptoms and may be the only indication of the underlying condition. Patients presenting with osteopenia, osteoporosis, or fractures may initially be evaluated for metabolic bone disorders, while underlying Crohn’s or Celiac disease remains undiagnosed and/or alters both diagnostic and therapeutic pathways.

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