Nephropathy

Nephropathy, also known as kidney disease, means damage to or disease of a kidney. Nephrosis is non-inflammatory nephropathy. Nephritis is inflammatory kidney disease.

Causes

Causes of nephropathy include deposition of the IgA antibodies in the glomerulus, administration of analgesics, xanthine oxidase deficiency, toxicity of chemotherapy agents, and long-term exposure to lead or its salts. Chronic conditions that can produce nephropathy include systemic lupus erythematosus, diabetes mellitus and high blood pressure (hypertension), which lead to diabetic nephropathy and hypertensive nephropathy, respectively.

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 (in 40-50% of the cases) is episodic frank hematuria which usually starts within a day or two of a non-specific upper respiratory tract infection (hence synpharyngitic) as opposed to post-streptococcal glomerulonephritis which occurs some time (weeks) 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.

Analgesics

One cause of nephropathy is the long term usage of analgesics. The pain medicines which can cause kidney problems include aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs, or NSAIDs. This form of nephropathy is "chronic analgesic nephritis," a chronic inflammatory change characterized by loss and atrophy of tubules and interstitial fibrosis and inflammation (BRS Pathology, 2nd edition).

Specifically, long term use of the analgesic phenacetin has been linked to renal papillary necrosis (necrotizing papillitis).

Xanthine oxidase deficiency

Another possible cause of nephropathy 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 (which can lead to kidney stones) and result in damage of the kidney. Xanthine oxidase inhibitors, like allopurinol, can cause nephropathy.

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 get 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.

Toxicity of Chemotherapy Agents

Nephropathy can be associated with some therapies used to treat cancer. The most common form of kidney disease in cancer patients is Acute Kidney Injury (AKI) which can usually be due to volume depletion from vomiting and diarrhea that occur following chemotherapy or occasionally due to kidney toxicities of chemotherapeutic agents. Kidney failure from break down of cancer cells, usually after chemotherapy, is unique to onconephrology. Several chemotherapeutic agents, for example Cisplatin, are associated with acute and chronic kidney injuries. Newer agents such as anti Vascular Endothelial Growth Factor (anti VEGF) are also associated with similar injuries, as well as proteinuria, hypertension and thrombotic microangiopathy.

Development

Kidney disease is a chronic non-communicable disease, having serious consequence if it can not be controlled effectively. Generally, the process of kidney disease development is from light to serious. The process of most kidney diseases is renal Insufficiency, renal failure, and then uremia.

References

1. ^ D'Amico, G (1987). "The commonest glomerulonephritis in the world: IgA nephropathy.". Q J Med 64 (245): 709â€"727. PMID 3329736. 
2. ^ Portilla D, Safar AM, Shannon ML, Penson RT. Cisplatin nephrotoxicity. In: UpToDate, Palevsky PM (Ed), UpToDate, Waltham, MA, 2013. http://www.uptodate.com/contents/cisplatin-nephrotoxicity
3. ^ Robinson, Emily S.; Khankin, Eliyahu V.; Karumanchi, S. Ananth; Humphreys, Benjamin D. (1 November 2010). "Hypertension Induced by Vascular Endothelial Growth Factor Signaling Pathway Inhibition: Mechanisms and Potential Use as a Biomarker". Seminars in Nephrology 30 (6): 591â€"601. doi:10.1016/j.semnephrol.2010.09.007. PMC 3058726. PMID 21146124.