J (joule)

J-tube (jejunostomy tube)

JAMA (Journal of the American Medical Association)

JAS (juvenile ankylosing spondylitis)

JBS (Johanson-Blizzard syndrome)

JCA (juvenile chronic arthritis)

JCAHO (Joint Commission on Accreditation of Healthcare Organizations)

JDM (juvenile dermatomyositis)

JHS (joint hypermobility syndrome)

JIA (juvenile idiopathic arthritis)