Abstract Disclosure: A. Rubenstein: None. A. Kondapalli: None. S. Agarwal: None. M. Bucovsky: None. I. Colon: None. N. Kil: None. S. Lewis: None. B. Lebwohl: None. P. Green: None. M. Walker: Advisory Board Member; Self; Alexion Pharmaceuticals, Inc.. The pathophysiology of osteoporosis related to celiac disease (CD) remains incompletely understood. High resolution peripheral quantitative computed tomography (HRpQCT) has revealed microarchitectural deficits in women with CD, but no data exist in men. We prospectively studied bone health using DXA and HRpQCT in 17 men with duodenal biopsy-confirmed CD (mean age 43±16 years; 82% white, 6% Asian, 12% other) and 5 male controls (mean age 40±12 years; 80% white, 20% Asian). Compared to controls, men with CD had lower self-rated health scores (p<0.05), but age, BMI, alcohol use, physical activity, acid blocker use, and vitamin D intake did not differ. Among patients with CD, 23.5% had other autoimmune diseases (type 1 diabetes, hypothyroidism, vitiligo, systemic sclerosis). At CD diagnosis, mean age was 34.3 ± 14.8. CD patients had a mean CD and gluten-free diet duration of 8 years. 29% of patients (n=5/17) were enrolled within 13 months of CD diagnosis. Mean tissue transglutaminase IgA, serum calcium, PTH, Vitamin D, and alkaline phosphatase were normal, but vitamin D levels were < 30 ng/mL in 36% (n=5/14) and PTH was elevated in 11% (n=1/9). T- (-0.5±1.5 vs. 0.8±0.8, p=0.03) and Z-scores (-0.1±1.4 vs. 1.1±0.9, p=0.05) by DXA were normal at all sites but tended to be lower at the 1/3-radius only in CD compared to controls. By HRpQCT, there were no differences. Compared to a larger control group including HRpQCT data from an additional 14 normative database controls (n=19), CD had lower radial cortical (-4.7%, p=0.02) and tibial trabecular (-13.3%, p=0.04) vBMD and a trend toward lower cortical volumetric BMD (vBMD; -3.5%, p=0.06) at the tibia. Within the CD group, longer CD duration was associated with worse tibial cortical vBMD at (r=-0.55, p=0.02). Higher PTH (n=9) correlated with lower lumbar spine areal BMD (r=-0.75, p=0.02), tibial trabecular thickness (Tb.Th; r=-0.77, p=0.02) as well as radial cortical vBMD (r=-0.81, p<0.01), trabecular Tb.Th (r=-0.78, p=0.01), and cortical thickness (r=-0.75, p=0.02). Those with greater dietary vitamin D intake had higher total vBMD (r=0.50, p=0.04) and trabecular thickness at the tibia (r=0.51, p=0.04). Similarly, higher 25-hydroxy vitamin D levels were associated with higher total hip aBMD (r=0.58, p=0.03). In summary, CD in men is associated with lower areal BMD at the 1/3-radius by DXA and lower vBMD at the radius and tibia by HRpQCT. Low vitamin D levels and secondary hyperparathyroidism may contribute. Further work is needed to understand the extent and pathophysiology of skeletal disease in men with CD. Presentation: 6/3/2024