What is Nephrology?
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. Patients are referred to nephrology specialists for various reasons, such as acute renal failure, chronic kidney disease, hematuria, proteinuria, kidney stones, hypertension, and disorders of acid/base or electrolytes.
A nephrologist is a medical doctor who has undertaken additional training to become an expert in nephrology. Additionally, due to their unique skills, nephrologists may provide care to people without kidney problems and may work in general/internal medicine, transplant medicine, immunosuppression management, intensive care medicine, clinical pharmacology, and perioperative medicine. Nephrologists may further sub-specialize in dialysis, kidney transplantation, chronic kidney disease, procedural nephrology, or other non-nephrology areas as described above. Procedures a nephrologist may perform include native kidney and transplant kidney biopsy, dialysis access insertion (temporary vascular access lines, tunneled vascular access lines, peritoneal dialysis access lines), fistula management (angiographic or surgical fistulogram and plasty), and bone biopsy.
History and physical examination are central to the diagnostic workup in nephrology. This may include inquires regarding family history, general medical history, diet, medication use, drug use, and occupation. Examination typically includes an assessment of volume state, blood pressure, skin, joints, abdomen, and flank.
Basic blood tests can be used to check the concentration of hemoglobin, platelets, sodium, potassium, chloride, bicarbonate, urea, creatinine, calcium, magnesium, or phosphate in the blood. All of these may be affected by kidney problems. The serum creatinine concentration can be used to estimate the function of the kidney, called the creatinine clearance or estimated glomerular filtration rate. More specialized tests can be ordered to discover or link certain systemic diseases to kidney failures such as infections (hepatitis B, hepatitis C), autoimmune conditions (systemic lupus erythematosus, ANCA vasculitis), paraproteinemias (amyloidosis, multiple myeloma), and metabolic diseases (diabetes, cystinosis).
Structural abnormalities of the kidneys are identified with imaging tests. These may include ultrasound, computed axial tomography (CT), scintigraphy (nuclear medicine), angiography, or magnetic resonance imaging (MRI). In certain circumstances, less invasive testing may not provide a certain diagnosis. Where the definitive diagnosis is required, a biopsy of the kidney (renal biopsy) may be performed. This typically involves the insertion, under local anesthetic and ultrasound guidance, of a core biopsy needle into the kidney to obtain a small slither of kidney tissue. The kidney tissue is then examined under a microscope, allowing direct visualization of the changes occurring within the kidney. Additionally, the pathology may also stage a problem affecting the kidney, allowing some degree of prognostication. In some circumstances, kidney biopsy will also be used to monitor response to treatment and identify early relapse.
Treatments in nephrology can include medications, blood products, surgical interventions (urology, vascular or surgical procedures), renal replacement therapy (dialysis or kidney transplantation), and plasma exchange. Kidney problems can have a significant impact on quality and length of life, and so psychological support, health education, and advanced care planning play key roles in nephrology. Chronic kidney disease is typically managed with the treatment of causative conditions (such as diabetes), avoidance of substances toxic to the kidneys (nephrotoxins like radiologic contrast and non-steroidal anti-inflammatory drugs), antihypertensives, diet, and weight modification and planning for end-stage renal failure. Impaired kidney function has systemic effects on the body. An erythropoietin stimulating agent may be required to ensure adequate production of red blood cells, activated vitamin D supplements and phosphate binders may be required to counteract the effects of kidney failure on bone metabolism, and blood volume and electrolyte disturbance may need correction.
Auto-immune and inflammatory kidney disease, such as vasculitis or transplant rejection, may be treated with immunosuppression. Commonly used agents are prednisolone, mycophenolate, cyclophosphamide, cyclosporin, tacrolimus, everolimus, thyroglobulin, and sirolimus. Newer, so-called "biologic drugs" or monoclonal antibodies, are also used in these conditions and include rituximab, basiliximab, and eculizumab. Blood products including intravenous immunoglobulin and a process known as plasma exchange can also be employed.
When the kidneys are no longer able to sustain the demands of the body, end-stage renal failure is said to have occurred. Without renal replacement therapy, death from renal failure will eventually result. Dialysis is an artificial method of replacing some kidney functions to prolong life. Renal transplantation replaces kidney function by inserting into the body a healthier kidney from an organ donor and inducing immunologic tolerance of that organ with immunosuppression. At present, renal transplantation is the most effective treatment for end-stage renal failure although its worldwide availability is limited by the lack of availability of donor organs.
Most kidney conditions are chronic conditions and so long-term follow-up with a nephrologist is usually necessary.