Kidney Lithiasis

Although most of this discussion concerns stones originating in the kidney, lithiasis may be primary to the bladder or the ureters. Whereas phosphate and oxalate stones develop more frequently in the kidney, bladder stones are usually of the urate type. The geographical distribution of urinary lithiasis varies considerably. The disease is common in central Russia, China, Canton, and India. However, in India and China bladder stones are the type seen most often, whereas renal stones are more common in America. 

Urinary lithiasis is a disease in which calculi form in the kidney and urinary tract. Roughly 5 % of the human population suffers to some degree from urinary lithiasis. A number of severely afflicted patients (e.g. ca. 60,000 in West Germany and more than 100,000 in the U.S.) are hospitalized yearly for major surgical treatment. Obviously, nephrolithiasis is not only a common ailment but also an issue of great social and economic consequence. 

Guitard J, Kamar N, Mouzin M, Borde JS, Tran-Van T, Durand D, et al. Sulfadiazine-related obstructive urinary tract lithiasis an unusual cause of acute renal failure after kidney transplantation. Clinical nephrology. 2005 May 63(5) 405-7. 

In conclusion, the kidney protects itself against calcium oxalate nephrocalcinosis/lithiasis at different levels. Failure or saturation of these protection mechanisms, might explain why patients develop renal and/ or urinary tract calcifications. 

Roie of Imaging in the Study of Pathoiogical Findings 321 Congenital Anomalies/Kidney Donors 321 Lithiasis 321 Neoplasms 324... 

Oxaluria is a rare disease occuring mainly between one and four years of age and most often in white males. The patient is usually afflicted with a chronic renal disease associated with normal blood pressure. Renal failure results from the deposition of pure calcium oxalate calculi into the pelvis and calices. The lithiasis causes chronic inflammation of the kidney with parenchymal involution, fibrosis, and formation of thick capsules that strip off with difficulty. Microscopic examination of the kidney demonstrates the presence of oxalate calculi in the tubules. Calcium oxalate is also frequently found in the arterial walls, but usually the glomeruli remain free of salt. Histologically, the calculi appear as globular or rhomboidal crystals they are slightly yellowish and doubly refrac-tile under polarized light [98-104]. 

In cats, pyridoxine deficiency is associated with the formation of calcium oxalate calculi in the kidneys. The magnesium and pyridoxine levels in the diet are related. Diets low in magnesium are responsible for increased incidence and severity of the oxalate lithiasis in the kidney, and the effect of the low-magnesium diet is counteracted by the administration of pyridoxine. These observations made in animals may have some relevance to the development of lithiasis in humans. Patients with recurring calcium oxalate stones in the kidney secrete more xanthurenic and pyridoxic acid than normal individuals, suggesting that lithiasis may result from deficient pyridoxine metabolism, possibly due to accelerated breakdown of the coenzyme. If other signs of pyridoxine deficiency develop, one must assume that the accelerated breakdown occurs only in a few organs, probably only in the kidneys. 

Lonsdale [87, 88] has reviewed the epidemiology of urinary lithiasis and concludes that bladder stones have become rare in adult man. The bladder stones Lonsdale found were urate stones and were believed to result from faulty diet. Bladder stones, composed of urate and oxalates, are seen in young people, rarely in the West, but commonly in India, Turkey, and Thailand. In contrast, kidney stones are a relatively frequent ailment in the West (200,000 new cases a year in the United States). Kidney stones are usually made of calcium oxalate, calcium phosphate, or MgNH4 phosphates. The incidence seems to be highest among those with sedentary professions, and renal lithiasis is said to constitute an occupational hazard among airplane pilots. 

Many conditions result in the increased concentration of special solutes in the urine, and many of these have been or will be described in more detail in other chapters. For example, primary or secondary hyperparathyroidism releases calcium from bone and leads to its precipitation in kidneys. In some inborn errors of metabolism, metabolites accumulate in the blood, are excreted in the kidney, and under the appropriate conditions are precipitated in the excretory system. Gout, cysteinuria, and oxaluria are among those diseases that cause renal lithiasis. 

A substance with similar immunological properties has been found in the kidney, where it is more abundant in the cortex than in the medulla. According to Boyce and King [90, 91], the mucoprotein is consistently found in the kidneys of patients with recently formed stones, but is rarely present in patients with other kidney diseases in which stones are not formed (e.g., renal carcinoma and severe renal arteriosclerosis). The mucoprotein has not been detected in normal kidneys or in patients with pyelonephritis, and the compound cannot be immunologically detected in blood serum, human saliva, or bone matrix. The only other tissue where this matrix substance has been detected is the intestine. (Boyce and King think that this is not a coincidence and that the reason for its presence in kidney and intestine is that both these organs are involved in calcium absorption.) But most important to the pathogenesis of lithiasis are the mucopolysaccharides found in urine. 

Fig. 5.7a-c. Megacalycosis and megaureter, a US sagittal scan ofthe left kidney. Unusual cystic dilatation of all the calyces. A lithiasis is visible at the lower pole, b US of the pelvis showing an associated dilated ureter (1.8 cm between crosses), c MR urography typical megacalycosis of the left kidney... 

Fig. 15.18. Pyonephrosis, uro-lithiasis and obstructive uropathy. Ultrasound. Sagittal scan of the left kidney. A li-thiasis is visible within the dilated urinary tract (arrow). The urine appears echogenic...

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