What is Nephrology?
Scope of the Specialty
Nephrology concerns the diagnosis and treatment of kidney diseases, including electrolyte disturbances and hypertension, and the care of those requiring renal replacement therapy, including dialysis and renal transplant patients. Many diseases affecting the kidney are systemic disorders not limited to the organ itself, and may require special treatment. Examples include acquired conditions such as systemic vasculitides (e.g. ANCA vasculitis) and autoimmune diseases (e.g., lupus), as well as congenital or genetic conditions such as polycystic kidney disease.
A nephrologist is a physician who has been trained in the diagnosis and management of kidney disease, by regulating blood pressure, regulating electrolytes, balancing fluids in the body, and administering dialysis. Nephrologists treat many different kidney disorders including acid-base disorders, electrolyte disorders, nephrolithiasis (kidney stones), hypertension (high blood pressure), acute kidney disease and end-stage renal disease. Nephrology is a subspecialty of internal medicine. In the United States, after medical school nephrologists complete a three year residency in internal medicine followed by a two year (or longer) fellowship in nephrology.
Knowledge of internal medicine is required to obtain certification. To become a nephrologist requires many years of school and training. Nephrologists also must be approved by the board. To be approved, the physician must fulfill the requirements for education and training in nephrology in order to qualify to take the board's examination. If a physician passes the examination, then he or she can become a nephrology specialist. Typically, nephrologists also need two to three years of training in an ACGME or AOA accredited fellowship in nephrology.
Information that a nephrologist learns in training are fluid and acid base and electrolyte physiology, medical management of acute and chronic renal failure, glomerular and vascular disorders, tubular/interstitial disorders, mineral metabolism, clinical pharmacology, hypertension, epidemiology, and nutrition. Procedures a nephrologist may learn in a training program include native and transplant kidney biopsies, ultrasound guidance, placement of temporary dialysis catheters, placement of tunneled hemodialysis catheters and placement of peritoneal dialysis catheters. Nearly all programs train nephrologists in continuous renal replacement therapy; fewer than half train in the provision of plasmapheresis. Once training is satisfactorily completed, the physician is eligible to take the ABIM or AOBIM nephrology examination. Subspecialties within nephrology include interventional nephrology, dialytician, and transplant nephrology.
Only pediatric trained physicians are able to train in pediatric nephrology, and internal medicine (adult) trained physicians may enter general (adult) nephrology fellowships. Physicians that achieved training in both medicine and pediatrics may subspecialize in both adult and pediatric nephrology.
Conditions Requiring a Nephrologist
Patients are referred to nephrology specialists for various reasons, such as:
- Acute renal failure, a sudden loss of renal function
- Chronic kidney disease, declining renal function, usually with an inexorable rise in creatinine.
- Hematuria, blood in the urine
- Proteinuria, the loss of protein especially albumin in the urine
- Kidney stones, usually only recurrent stone formers.
- Chronic or recurrent urinary tract infections
- Hypertension that has failed to respond to multiple forms of anti-hypertensive medication or could have a secondary cause
- Electrolyte disorders or acid/base imbalance
As with the rest of medicine, important clues as to the cause of any symptom are gained in the history and physical examination.
Laboratory tests are almost always aimed at: urea, creatinine, electrolytes, and urinalysis, which is frequently the key test in suggesting a diagnosis.
More specialized tests can be ordered to discover or link certain systemic diseases to kidney failure such as hepatitis b or hepatitis c, lupusserologies, paraproteinemias such as amyloidosis or multiple myeloma or various other systemic diseases that lead to kidney failure. Collection of a 24-hour sample of urine can give valuable information on the filtering capacity of the kidney and the amount of protein loss in some forms of kidney disease. However, 24-hour urine samples have recently, in the setting of chronic renal disease, been replaced by spot urine ratio of protein and creatinine.
Other tests often performed by nephrologists are:
- Renal biopsy, to obtain a tissue diagnosis of a disorder when the exact nature or stage remains uncertain.;
- Ultrasound scanning of the urinary tract and occasionally examining the renal blood vessels;
- CT scanning when mass lesions are suspected or to help diagnosis nephrolithiasis;
- Scintigraphy (nuclear medicine) for accurate measurement of renal function (rarely done), and MAG3 scans for diagnosis of renal artery disease or 'split function' of each kidney;
- Angiography or Magnetic resonance imaging angiography when the blood vessels might be affected
Many kidney diseases are treated with medication, such as steroids, DMARDs (disease-modifying antirheumatic drugs), antihypertensives (many kidney diseases feature hypertension). Often erythropoietin and vitamin D treatment is required to replace these two hormones, the production of which stagnates in chronic kidney disease.
When chronic kidney disease progresses to stage five, dialysis or transplant is required. Please refer to the main articles dialysis and renal transplant for a comprehensive account of these treatments.
Sub-specialties within nephrology include interventional nephrologists who focus on access placement and maintenance, a dialytician who focus upon ordering dialysis for patients, and transplant nephrologists who focus on the acute or sub-acute monitoring of immunosuppression in the transplant patient.
If patients proceed to transplant, nephrologists will continue to follow patients to monitor the immunosuppressive regimen and watch for the infection that can occur post transplant.
In the USA, the National Kidney Foundation is a national organization representing patients and professionals who treat kidney diseases. Founded in 1966, the American Society of Nephrology (ASN) is the world’s largest professional society devoted to the study of kidney disease. In the United Kingdom, the National Kidney Federation represents patients, and the Renal Association represents renal physicians and works closely with the National Service Framework for kidney disease. The Renal Support Network (RSN) is a nonprofit, patient-focused, patient-run organization that provides non-medical services to those affected by chronic kidney disease (CKD). The American Association of Kidney Patients (AAKP) is a non-profit, patient-centric group focused on improving the health and well-being of CKD and dialysis patients.