Physiology of Kidney Stones - Research Paper Example

Abstract Kidneys play a major role in elimination of toxins from the bloodstream. Additionally they are involved in reabsorption of water and balancing of substances such as salts in the body. When the kidneys are diseased, the above functions cannot occur normally. Kidney related diseases are among the major causes of death in animals since most kidney diseases are incurable. The failures are mainly caused by improper husbandly and diet which often result in renal failure and other ailments. Renal failure arises due to toxics, which could arise after a period of treatment of or at any time. Kidney stones affect several domestic animals. Kidney stone is one of the major kidney diseases, which are also referred to as renal calculus. It is characterized by concretion or accumulation of crystals that are formed in the kidney as byproducts of urine and dietary minerals. Depending on the location and composition, Urinary stones are referred to using different names. If located within the kidney they are referred to as kidney stones, or nephrolithiasis, ureterolithiasis to refer to urinary stones located in the ureter. Cystolithiasis refers to urinary stones locate in the bladder. Urinary stones can be calcium containing, struvite, or uric acid. Kidney stones occur when mineral such as calcium oxalate and calcium phosphate mineralize to form crystals, which may harden to form the stones. This paper focuses on the physiology of kidney stones. Introduction Kidney stones, also known as Nephrolithiasis is a condition that results from crystallization of mineral along the urinary tract or in the kidney. Kidney stones are a common kidney condition that affects several mammals such as dogs and cats. When they form, kidney stones obstruct urine flow. The obstruction could be along the path between kidney and urinary bladder of from urinary bladder towards outside the body. Moreover, the stones are capable of travelling through the urinary systems to various parts of urinary system. Symptoms of kidney stones include frequent urination, recurrent infections on the urinary tract, and blood in the urine. Extreme obstruction may result in painful urination. Location and Physiology of Kidney Stones Kidney stones appear in urine as hardened accumulations of minerals such as calcium oxalate, struvite, and urate. The stones have different size and shape. However, the can move with the urine and are deposited along the urinary tract. Depending on their location, kidney stones are referred using different terms. When located in the kidney or renal they are referred to as kidney stones, or nephrolithiasis. The crystallization can occur along the ureter resulting in a condition called ureterolithiasis. Cystolithiasis refers to urinary stones located within the bladder. Mineral salts such as calcium phosphate and calcium oxalate contained in the urine are capable of forming crystal through mineralization. Such crystals can harmful to animals. However, normal urine contains macromolecules, which give it the capacity to prevent formation of the crystals. Some breeds of animals are more prone to kidney stones than others. Struvite stones are mainly caused by bladder infections, which result in formation of ammonium and component of struvite stones. Ammonium biurate stones are another form of kidney stones that form in animals with liver diseases where the liver becomes incapable of removing uric acid in the body resulting in formation of stones. Mo, Liaw, Evan, Sommer, Lieske, and Wu (1935-1940) did a research on mice to determine how renal calcinosis and stone formation occurs in mice. Their study showed that null mice lacking osteopontin, Tamm-Horsfall protein, are likely to form calcium and phosphate deposits in the renal papillae. However, wild type mice are less likely to have oxalate overload hence less prone to kidney stones. The enzyme osteopotonin is responsible of preventing crystallization hence formation of kidney stones. This study is relevant to domestic animals, which are mammals. The research by Mo, Liaw, Evan, Sommer, Lieske, and Wu (1939-1941) showed that osteopontin (OPN) and Tamn-Horsfall Protein (THP) are capable of influencing crystallization even in vitro. In the animal body, OPN is found at the ascending loop of henle as well as in the renal papillary epithelium. OPN is capable of causing calcium crystal nucleation. Additionally OPN causes accumulation and adhesion of Mo, Huang and Zhu (1159-1164) argue that the importance of a protein called Tamm-Horsefall in preventing formation of calcium Oxalate crystal. The study made use of TPH knockout mice in which formation of calcium oxalate was induced, which is a precursor of kidney stones in animals. In presence of THP, the renal stones could not form. This demonstrated the role of THP in preventing formation of kidney stones. Therefore, animals lacking this enzyme are likely to form kidney stones. Factors Influencing Formation of Kidney Stones Several factors influence the pathways of Kidney stone formation. Some factors involve interstitial plaque while others entail intra-tubular crystal deposition. Under normal circumstances, pro- and anti-crystallization forces exist in equilibrium and physiological processes proceed normally. However, disequilibrium results in crystallization of the urine constituents. Animal may have urine saturated with calcium oxalate and calcium phosphate, which stimulate stone formation. Deficiency of urinary macromolecules can disrupt pro and antilithogenic forces leading to eventual formation of Kidney stones (Mo, Evan and Sommer, Lieske and Wu 1938-1940). TPH is a urinary protein found in most mammals and affects calcium crystallization. If present, TPH acts as a protective protein since it prevents formation of calcium microcrystals. Lack of OPN and THP thus predisposes animals to calcinosis in cases of hyperroxauric situations. After using mice deficient from OPN and THP, Mo, Liaw, Evan, Sommer, Lieske and Wu, established that OPN and THP inhibit renal calcium crystallization. Additionally, the study demonstrated that defectiveness of OPN and THP physiology results inn renal stone formation. Other factors that influence formation of kidney stones include the type of food fed to the animal, genetic predisposition, infections along urinary tract and metabolic disorders. The stones cause hardness in the kidney tubules. Lulich Jody, Osborne and Sanderson (319-323) did a study to asssess the effect of sodium chloride supplements on the urinary calcium excretion. After 24 hours, the level of calcium in the urine increased. Additonally the study showed that The study established that sodium chloride supplements can be used for urolith prevention of calcium oxalate crystalization. Therefore, their study provided insights on ways kidney stoney formation can be prevented in animals. Butler, Inzunza and Suzuki (1122–1124) did a study on aryl hydrocarbon receptor (AhR) knockout mice, a species that is characterized by presence of large yellowish stines in the urinary bladder. Although the rats under study had elevated levels of uric acid in their urine, the uric acid levels in the serum were normal. This is because mice have an enzyme referred to as urate oxidase that catalyzes conversion of uric acid to allatoinin. However, this enzyme is lacking in other mamals hence the incapability of breaking down toxic substances that could be in the feeds. This experiment helped establish some of the predisposing factors for kidney stone formation in animals. The study suggested that kidney stones can also form as a form of cancer. According to Khan (236-238), kidney stones originate from renal tubular lamina. However, the calcium oxalate deposition can occur anywhere in the kidney and result in formation of calcific crystals. Although the study was done using mice, Khan () foung out that kidney stone prevalence is higher in female as compare to males. Khan recommeded the need for further research on the physiology on the kidney of female rats which makes them more vulnerable to kidney stones. The main impact of kidney stones is that it leads to reduced efficiency of blood foltration. This results in retention of wastes in the blood. Additonally, kidney stones are very painful and cause irritiation in affected animal. Kidney stones can lead to eventual failure of the kidney or even death. Conclusions Kidney is an important organ concerned with removal of wastes from the blood. The kidney is vulnerable to many diseases, which are incurable. There is thus need for prevention of such diseases to prevent kidney failure. Kidney stones result from change in mineral concentrations along the urinary tract. This is caused by imbalances in minerals such as calcium oxalate, urate, and struvite. OPN and THP prevent super saturation of urine with minerals, which could lead to crystallization of minerals such as calcium and phosphate resulting in kidney stones. Deficiency of either of OPN and THP results in renal calcium crystallization. This may eventually lead to kidney stones formation. Depending on where they are formed and formation pathway, kidney stones can be grouped into different categories. Kidney stones are located in the kidneys and are composed of crystals of calcium oxalate and calcium phosphate. Kidney stones are characterized by frequent urination, pain on the bladder and frequent infections of the bladder. Works Cited Butler, Ryan, et al. "Uric acid stones in the urinary bladder of aryl hydrocarbon receptor (AhR) knockout mice." Proc Natl Acad Sci U.S.A. Vol 109(4) . (2012): 1122–1126. Khan, Shahrukh. "Animal models of kidney stone formation: an analysis." World Journal of Urology (1997): 236-243. Lulich Jody, Carl Osborne and Sherry Sanderson. "Effects of Dietary Supplementation With Sodium Chloride on Urinary Relative Supersaturation with Calcium Oxalate in Healthy dogs." American journal of veterinary research. Vol 66(2):319-24. (2005): 319-324. Mo, Huang, et al. Tamm-Horsfall Protein Is A Critical Renal Defense Factor Protecting Against Calcium Oxalate Crystal Formation." Kidney International, Vol 66 (2004): 1159-1166. Mo, Lan, et al. Renal Calcinosis And Stone Formation In Mice Lacking Osteopontin, Tamm-Horsfall Protein, Or Both. American Journal of Physiology, Vol 293, No. 6 (2007): 1935-1943. Read More