Stephen Knohl, MD (photo by Jim Howe) Stephen Knohl, MD (photo by Jim Howe) Some people don't realize they have kidney stones, and others may experience excruciating pain. Patients may seek care through a hospital emergency department or their primary care provider. They may also seek treatment from a urologist or a kidney specialist, called a nephrologist, such as Upstate's Some people don't realize they have kidney stones, and others may experience excruciating pain. Patients may seek care through a hospital emergency department or their primary care provider. They may also seek treatment from a urologist or a kidney specialist, called a nephrologist, such as Upstate's Stephen Knohl, MD. Stephen Knohl, MD. Knohl explains how kidney stones form, what can be done to prevent them and what to expect from a visit with a nephrologist. Knohl explains how kidney stones form, what can be done to prevent them and what to expect from a visit with a nephrologist.