Patient Portal - Siouxland Sioux City, Iowa (IA), MercyOne . Health (Just Now) Attn: Medical Records MercyOne Siouxland Medical Center 801 5th Street Sioux City, IA 51101. With questions, please call the MercyOne at 712-279-2081 from 8 a.m. to 4:30 p.m. Clinic Records.To request clinic records, please contact your clinic directly.Our Medical Records department does not have access to that ....