Nephrology is a specialty of adult internal medicine and pediatric medicine that concerns with study of the kidneys, specifically normal kidney function and kidney disease, the preservation of kidney health, and the treatment of kidney disease, from diet and medication to renal replacement therapy. The word “renal” is an adjective meaning “relating to the kidneys”, and its roots are French or late Latin. Whereas according to some opinions, "renal" and "nephro" should be replaced with "kidney" in scientific writings such as "kidney medicine" or "kidney replacement therapay", other experts have advocated preserving the use of renal and nephro as appropriate including in "nephrology" and "renal replacement therapy", respectively.
Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become foamy. Severe proteinurina can cause nephrotic syndrome in which there is worsening swelling of the body.
Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes protein in the urine, low blood albumin levels, high blood lipids, and significant swelling. Other symptoms may include weight gain, feeling tired, and foamy urine. Complications may include blood clots, infections, and high blood pressure.
Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys are functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may resolve; and chronic kidney failure, which develops slowly and can often be irreversible. Symptoms may include leg swelling, feeling tired, vomiting, loss of appetite, and confusion. Complications of acute and chronic failure include uremia, high blood potassium, and volume overload. Complications of chronic failure also include heart disease, high blood pressure, and anemia.
Nephritis is inflammation of the kidneys and may involve the glomeruli, tubules, or interstitial tissue surrounding the glomeruli and tubules.
IgA nephropathy (IgAN), also known as Berger's disease, or synpharyngitic glomerulonephritis, is a disease of the kidney and the immune system; specifically it is a form of glomerulonephritis or an inflammation of the glomeruli of the kidney. Aggressive Berger's disease can attack other major organs, such as the liver, skin and heart.
Henoch–Schönlein purpura (HSP), also known as IgA vasculitis, is a disease of the skin, mucous membranes, and sometimes other organs that most commonly affects children. In the skin, the disease causes palpable purpura, often with joint pain and abdominal pain. With kidney involvement, there may be a loss of small amounts of blood and protein in the urine, but this usually goes unnoticed; in a small proportion of cases, the kidney involvement proceeds to chronic kidney disease. HSP is often preceded by an infection, such as a throat infection.
Glomerulonephritis (GN) is a term used to refer to several kidney diseases. Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the name, but not all diseases necessarily have an inflammatory component.
Diabetic nephropathy, also known as diabetic kidney disease, is the chronic loss of kidney function occurring in those with diabetes mellitus. Diabetic nephropathy is one of the leading causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD) globally. Protein loss in the urine due to damage to the glomeruli may become massive, and cause a low serum albumin with resulting generalized body swelling (edema) and result in the nephrotic syndrome. Likewise, the estimated glomerular filtration rate (eGFR) may progressively fall from a normal of over 90 ml/min/1.73m2 to less than 15, at which point the patient is said to have end-stage renal disease. It usually is slowly progressive over years.
Hypertensive kidney disease is a medical condition referring to damage to the kidney due to chronic high blood pressure. It manifests as hypertensive nephrosclerosis. It should be distinguished from renovascular hypertension, which is a form of secondary hypertension, and thus has opposite direction of causation.
Focal segmental glomerulosclerosis (FSGS), also known as “focal glomerular sclerosis” or “focal nodular glomerulosclerosis,” is a histopathologic finding of scarring (sclerosis) of glomeruli and damage to renal podocytes. This process damages the filtration function of the kidney, resulting in protein loss in the urine. FSGS is a leading cause of excess protein loss--nephrotic syndrome—in children and adults. Signs and symptoms include proteinuria, water retention, and edema. Kidney failure is a common long-term complication of disease. FSGS can be classified as primary versus secondary depending on whether a particular toxic or pathologic stressor can be identified as the cause. Diagnosis is established by renal biopsy, and treatment consists of glucocorticoids and other immune-modulatory drugs. Response to therapy is variable, with a significant portion of patients progressing to end-stage kidney failure. FSGS is estimated to occur in 2-3 persons per million, with males and African peoples at higher risk.
Renal vein thrombosis (RVT) is the formation of a clot in the vein that drains blood from the kidneys, ultimately leading to a reduction in the drainage of one or both kidneys and the possible migration of the clot to other parts of the body. First described by German pathologist Friedrich Daniel von Recklinghausen in 1861, RVT most commonly affects two subpopulations: newly born infants with blood clotting abnormalities or dehydration and adults with nephrotic syndrome.
HIV-associated nephropathy (HIVAN) refers to kidney disease developing in association with infection by human immunodeficiency virus, the virus that causes AIDS. The most common, or "classical", type of HIV-associated nephropathy is a collapsing focal segmental glomerulosclerosis (FSGS), though other forms of kidney disease may also occur. Regardless of the underlying histology, kidney disease in HIV-positive patients is associated with an increased risk of death.
Congenital nephrotic syndrome is a rare kidney disease which manifests in infants during the first 3 months of life, and is characterized by high levels of protein in the urine (proteinuria), low levels of protein in the blood, and swelling. This disease is primarily caused by genetic mutations which result in damage to components of the glomerular filtration barrier and allow for leakage of plasma proteins into the urinary space.
Loin pain hematuria syndrome (LPHS) is the combination of debilitating unilateral or bilateral flank pain and microscopic or macroscopic amounts of blood in the urine that is otherwise unexplained.
Glomerulonephrosis is a non-inflammatory disease of the kidney (nephrosis) presenting primarily in the glomerulus as Nephrotic Syndrome. The nephron is the functional unit of the kidney and it contains the glomerulus, which acts as a filter for blood to retain proteins and blood lipids. Damage to these filtration units results in important blood contents being released as waste in urine. This disease can be characterized by symptoms such as fatigue, swelling, and foamy urine, and can lead to chronic kidney disease and ultimately end-stage renal disease, as well as cardiovascular diseases. Glomerulonephrosis can present as either primary glomerulonephrosis or secondary glomerulonephrosis.
Diffuse proliferative glomerulonephritis (DPGN) is a type of glomerulonephritis that is the most serious form of renal lesions in SLE and is also the most common, occurring in 35% to 60% of patients. Most of the glomeruli show endothelial and mesangial proliferation, affecting the entire glomerulus, leading to diffuse hypercellularity of the glomeruli, producing in some cases epithelial crescents that fill Bowman's space. When extensive, immune complexes create an overall thickening of the capillary wall, resembling rigid "wire loops" on routine light microscopy. Electron microscopy reveals electron-dense subendothelial immune complexes. Immune complexes can be visualized by staining with fluorescent antibodies directed against immunoglobulins or complement, resulting in a granular fluorescent staining pattern. In due course, glomerular injury gives rise to scarring (glomerulosclerosis). Most of these patients have hematuria with moderate to severe proteinuria, hypertension, and renal insufficiency.
Sickle cell nephropathy is a type of nephropathy associated with sickle cell disease which causes kidney complications as a result of sickling of red blood cells in the small blood vessels. The hypertonic and relatively hypoxic environment of the renal medulla, coupled with the slow blood flow in the vasa recta, favors sickling of red blood cells, with resultant local infarction. Functional tubule defects in patients with sickle cell disease are likely the result of partial ischemic injury to the renal tubules.
Renal biopsy is a medical procedure in which a small piece of kidney is removed from the body for examination, usually under a microscope. Microscopic examination of the tissue can provide information needed to diagnose, monitor or treat problems of the kidney.
Light chain deposition disease (LCDD) is a rare blood cell disease which is characterized by deposition of fragments of infection-fighting immunoglobulins, called light chains (LCs), in the body. LCs are normally cleared by the kidneys, but in LCDD, these light chain deposits damage organs and cause disease. The kidneys are almost always affected and this often leads to kidney failure. About half of people with light chain deposition disease also have a plasma cell dyscrasia, a spectrum of diseases that includes multiple myeloma, Waldenström's macroglobulinemia, and the monoclonal gammopathy of undetermined significance premalignant stages of these two diseases. Unlike in AL amyloidosis, in which light chains are laid down in characteristic amyloid deposits, in LCDD, light chains are deposited in non-amyloid granules.
