Vitamin D Level Effects on Nailfold Capillaroscopy in a Sample of Egyptian Mixed Connective Tissue Disease patients

Background: The current pilot study aims to determine the potential association between serum vitamin D ( Vit.D) levels and peripheral microvascular alterations in Egyptian patients diagnosed with Mixed Connective Tissue Disease (MCTD) using Nailfold video-capillaroscopy (NVC).Aim: To determine the potential correlation between serum vitamin D levels as well as peripheral microvascular alterations in Egyptian patients diagnosed with MCTD, utilizing NVC evaluationMethods: The present cross-sectional, observational study collected samples from 25 female MCTD patients. Patients’ ages ranged from 25 to 50 years, with a mean age of 32.6±8.8 and a disease duration ≤5 years (range 0-5 years, mean: 2.7±1.4 years). The patients underwent a serum 25-OH vitamin D assessment and NVC. NC parameters were analyzed and scored for four fingers of each hand, excluding thumbs. The association between serum vitamin D and NC findings and various demographic, clinical, and lab parameters was examined.Results: The study revealed a notable decrease in capillary density among individuals with inadequate levels of serum Vit.D (<20 ng/mL) compared to those with sufficient Vit.D levels (p 0.012). A significant negative association was also detected between capillary density score and Vit.D level (p 0.002). Conversely, a strong negative association was found between Vit.D levels and capillary hemorrhages (p 0.014). Serum vitamin D level exhibited a statistically significant moderate diagnostic performance in predicting the presence of low capillary density and capillary hemorrhage (p 0.015 and p 0.005, respectively).Conclusion: Vitamin D deficiency (< 20ng/mL) is prevalent among Egyptian patients with MCTD. In MCTD patients, capillary density and microhemorrhages were the main parameters in NC affected by low vitamin D levels.