Nephrology is the subspecialty of internal medicine that focuses on the diagnosis and treatment of diseases of the kidney. Because the kidney performs so many critical functions, nephrologists maintain expertise in primary kidney disorders, but also the management of the systemic consequences of kidney dysfunction. Although the prevention and identification and management of early kidney disease is a large part of general internal medicine practice, nephrologists are usually called upon to assist and manage more complex or advanced nephrologic disorders.

Examples of conditions cared for by nephrologists include primary kidney disorders such as glomerular diseases (such as glomerulonephritis or the nephrotic syndrome), tubulointerstitial kidney diseases, tubular defects, and the effects of toxins on the kidney, including various diagnostic and therapeutic agents. Knowledge of disorders of the kidney vasculature (such as renal artery stenosis), infections and neoplasms of the kidney, and abnormalities of the kidney, collecting system and bladder (such as nephrolithiasis) are important aspects of nephrology practice. A thorough understanding of the involvement of the kidneys in other systemic diseases (such as vasculitis or heart failure) is a primary role of nephrologists, and because of the central role of the kidney in maintaining blood pressure, nephrologists also possess expertise in the management of hypertension, particularly when difficult to control. Nephrologists also help in managing fluid, electrolyte, and acid-base disturbances, particularly those occurring in advanced kidney disease. A major role of nephrology is the oversight of dialysis (including hemodialysis and peritoneal dialysis) in patients requiring renal replacement therapy, and participation in the kidney transplant process, if indicated.