aDivision of Nephrology, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA

bDivision of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

Correspondence to Chih-Jen Cheng, MD, PhD, Division of Nephrology, Department of Internal Medicine University of Iowa Carver College of Medicine 285 Newton Road, 3270B CBRB Iowa City, IA 52242-1109, USA. Tel: +1 319 335 9403; fax: +1 319 678 3020; e-mail: [email protected]