Nephrology concerns itself with the study of normal kidney function, kidney problems, the treatment of kidney problems and renal replacement therapy (dialysis and kidney transplantation). Systemic conditions that affect the kidneys (such as diabetes and autoimmune disease) and systemic problems that occur as a result of kidney problems (such as renal osteodystrophy and hypertension) are also studied in nephrology.
Problems with the kidney can be classified according to the site of the predominant problem. The kidney is microscopically made up of the glomeruli, renal tubules, collecting ducts, interstitum and vasculature.
The glomerulus is the filtration part of the kidney. Problems with the glomerulus can include vasculitis (both renal-limited and as part of a systemic disease), anti-glomerular basement membrane disease and Goodpasture's disease, lupus nephritis, IgA nephropathy and Henoch–Schönlein nephritis, membranoproliferative glomerulonephritis including dense deposit disease and cryoglobulinaemic glomerulonephritis, minimal change disease, focal and segmental glomerulosclerosis, membranous nephropathy, renal amyloidosis, myeloma cast nephropathy and thrombotic microangiopathy. Glomerular disease is often the cause of the nephrology clinical syndromes, nephrotic syndrome and nephritic syndrome. Diabetes, the leading cause of renal failure in the developed world, damages the glomerulus.
The renal tubules, collecting ducts and interstitium are all sites of urine formation in which excretion, re-absorption and concentration of electrolyes in the urine occurs. Problems here include acute and chronic interstitial nephritis, reflux nephropathy and electrolyte handling disorders (Gittleman's syndrome and Barter syndrome). Vasculitis, atheroembolic disease, renal artery stenosis, ischemic nephritis and kidney trauma all involve the renal vasculature.
Inflammation or scarring of the kidney can lead to a deterioration in its function, causing the clinical problems of acute renal failure (now called acute kidney injury) or chronic renal failure (now called chronic kidney disease).
The kidney plays a key role in a regulating homeostasis and so kidney problems can have widespread ramifications. These include hypertension, electrolyte disturbance, renal anaemia, renal osteodystrophy, uraemia and oedema. Nephrologists may play a role in managing secondary hypertension, hypertensive urgencies and hypertensive emergencies. Chronic kidney disease, dialysis and renal transplantation are associated with accelerated vascular disease including higher risks of stroke, heart attack and peripheral vascular disease. Finally, dialysis and renal transplantation are associated with higher risks of infection, including Staphylococcus sepsis, cytomegalovirus infection, polyoma virus infection and other common community infections.
Pregnancy places a physiologic stress on the kidneys. Nephrologists may manage pre-eclampsia, HEELP syndrome and eclampsia. They may be asked to investigate proteinuria during pregnancy. Finally, nephrologists may often assist with the medical management of patients with renal disease or renal transplants who are pregnant. Some nephrologists may have more broader interests in obstetric medicine.
A number of hereditary and inherited conditions may affect the kidneys. These include polycystic kidney disease, sickle cell disease, Alport's disease, familial interstitial nephritis and Fanconi syndrome. Structural abnormalities of the urologic tract can also affect the kidneys.