Association of mixed tobacco and nicotine exposure with hematological parameters and serum ferritin: a cross-sectional study of young adults at Badr University in Cairo (BUC), Egypt - Amany M. Elshamy; Sandra S. Samy; Mariam A. El Shater; Shahd M. Fouad; Farah M. El Sayed; Ali M. Khalil; Hanaa A. Amer (The Egyptian Journal of Internal Medicine, 2026)