Kidney disease
Kidney diseases, or renal diseases, technically referred to as nephropathies, are pathological conditions affecting the kidneys—the organs that facilitate removal of waste products and toxins from the bloodstream, regulate the body's concentration of electrolytes, maintain the appropriate acid-base balance of plasma, and produce urine as a byproduct of metabolism.
When used colloquially, the term kidney disease may refer to chronic kidney disease, an umbrella term for any progressive loss of kidney function over at least three months, from any cause. In contrast, kidney damage over a shorter period of time is known as acute kidney injury.
From a technical standpoint, the heterogenous group of kidney diseases can be broadly divided into categories based on which anatomical structures are involved: the glomeruli, the filtering capillaries of the kidney; tubules, which carry filtered blood; the renal interstitium, the fluid-filled space between these structures; and the renal blood vessels, which deliver blood towards and away from the kidney. Glomerular disease, or glomerulonephritis, can be further divided into the nephritic and nephrotic syndromes, which are respectively characterized by blood and protein leaking into the urine.
All forms of kidney disease, glomerular or otherwise, have the potential to damage all four components of the kidney, culminating in end-stage renal disease—the stage of disease at which dialysis or a kidney transplant are necessary.
Rates for both chronic kidney disease and mortality have increased, associated with the rising prevalence of diabetes and the aging global population. The World Health Organization has reported that "kidney diseases have risen from the world's nineteenth leading cause of death to the ninth, with the number of deaths increasing by 95% between 2000 and 2021." In the United States, prevalence has risen from about one in eight in 2007, to one in seven in 2021.
Causes
Causes of kidney disease include deposition of the Immunoglobulin A antibodies in the glomerulus, administration of analgesics, xanthine oxidase deficiency, toxicity of chemotherapy agents, and a long-term exposure to lead or its salts. Chronic conditions that can produce nephropathy include systemic lupus erythematosus, as well as diabetes mellitus and high blood pressure, which lead to diabetic nephropathy and hypertensive nephropathy, respectively.[Autosomal dominant polycystic kidney disease]
"Autosomal dominant polycystic kidney disease is the most common genetic disease, affecting a half million Americans. The clinical phenotype can result from at least two different gene defects. One gene that can cause ADPKD has been located on the short arm of chromosome 16."[IgA nephropathy]
IgA nephropathy is the most common glomerulonephritis throughout the world Primary IgA nephropathy is characterized by deposition of the IgA antibody in the glomerulus. The classic presentation is episodic frank hematuria which usually starts within a day or two of a non-specific upper respiratory tract infection as opposed to post-streptococcal glomerulonephritis which occurs some time after initial infection. Less commonly gastrointestinal or urinary infection can be the inciting agent. All of these infections have in common the activation of mucosal defenses and hence IgA antibody production.Polycystic disease of the kidneys
Additional possible cause of nephropathy is due to the formation of cysts or pockets containing fluid within the kidneys. These cysts become enlarged with the progression of aging causing renal failure. Cysts may also form in other organs including the liver, brain, and ovaries. Polycystic kidney disease is a genetic disease caused by mutations in the PKD1, PKD2, and PKHD1 genes. This disease affects about half a million people in the US. Polycystic kidneys are susceptible to infections and cancer.Xanthine oxidase deficiency
Another possible cause of Kidney disease is due to decreased function of xanthine oxidase in the purine degradation pathway. Xanthine oxidase will degrade hypoxanthine to xanthine and then to uric acid. Xanthine is not very soluble in water; therefore, an increase in xanthine forms crystals and result in damage to the kidney. Xanthine oxidase inhibitors, like allopurinol, can cause nephropathy.Diabetes
Diabetic nephropathy is a progressive kidney disease caused by angiopathy of the capillaries in the glomeruli. It is characterized by nephrotic syndrome and diffuse scarring of the glomeruli. It is particularly associated with poorly managed diabetes mellitus and is a primary reason for dialysis in many developed countries. It is classified as a small blood vessel complication of diabetes.Lupus
Despite expensive treatments, lupus nephritis remains a major cause of morbidity and mortality in people with relapsing or refractory lupus nephritis.COVID-19
is associated with kidney disease. In patients hospitalized with COVID-19, the prevalence of acute kidney injury is estimated to be 28%, and the prevalence of renal replacement therapy is estimated to be 9%.Analgesics
One cause of nephropathy is the long term usage of pain medications known as analgesics. The pain medicines which can cause kidney problems include aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen. This form of nephropathy is "chronic analgesic nephritis", a chronic inflammatory change characterized by loss and atrophy of tubules and interstitial fibrosis and inflammation.Specifically, long-term use of the analgesic phenacetin has been linked to renal papillary necrosis.