Nephrology is a subspecialty of internal medicine concerned with diagnosing and managing diseases of the kidneys and urinary system. Nephrologists commonly encounter conditions such as hypertension; fluid, electrolyte, acid-base, and mineral imbalances; glomerulonephritis; and polycystic kidney. Patients with end-stage renal disease, often caused by diabetes or hypertension, may require hemodialysis or peritoneal dialysis. Physicians in this specialty also consult with surgeons about potential kidney transplant recipients and help manage their immunosuppressive regimen after transplantation. This is a focused specialization requiring a broad knowledge of internal medicine. Nephrologists usually practice in partnerships or groups with other nephrologists, because the care of patients with renal disease often involves intensive, around-the-clock professional service.