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Kidney stone
ICD9 = 592.0| ICDO = | Image = Kidney Stone Image 4172-PH.jpg | Caption = Ultrasonic instrument and kidney stone | OMIM = | MedlinePlus = 000458 | eMedicineSubj = med | eMedicineTopic = 1600 | DiseasesDB = 11346 | }} Kidney stones, also known as nephrolithiases, urolithiases or renal calculi, are solid accretions (crystals) of dissolved mineralsin urinefound inside the kidneysor ureters. They vary in size from as small as a grain of sand to as large as a golf ball. Kidney stones typically leave the body in the urine stream; if they grow relatively large before passing (on the order of millimeters), obstruction of a ureter and distention with urine can cause severe painmost commonly felt in the flank, lower abdomen and groin.
AetiologyConventional wisdom has held that consumption of too much calciumcan aggravate the development of kidney stones, since the most common type of stone is calcium oxalate. However, strong evidence has accumulated demonstrating that low-calcium diets are associated with higher stone risk and vice-versa for the typical stone former. Other examples of kidney stones include struvite(magnesium, ammoniumand phosphate), uric acid, calcium phosphate, or cystine(the amino acidfound only in people suffering from cystinuria). The formation of struvite stones is associated with the presence of urease splitting bacteria (Klebsiella, Serratia, Proteus, Providencia species) which can split urea into ammonia, most commonly Proteus mirabilis. SymptomsKidney stones are usually idiopathicand asymptomaticuntil they obstruct the flow of urine. Symptoms can include acute flank pain(renal colic), nauseaand vomiting, restlessness, dull pain, hematuria, and possibly feverif infectionis present. Acuterenal colic is described as one of the worst types of pain that a patient can suffer from. But there are also people who have no symptoms until their urine turns bloody—this may be the first symptom of a kidney stone. Diagnosis & InvestigationDiagnosis is usually made on the basis of the location and severity of the pain, which is typically colicin nature (comes and goes in spasmodic waves). Radiological imaging is used to confirm the diagnosis and a number of other tests can be undertaken to help establish both the possible cause and consequences of the stone. The relatively dense calcium renders these stones radio-opaque and they can be detected by a traditional X-rayof the abdomen that includes Kidneys, Ureters and Bladder—KUB. This may be followed by an IVP(Intravenous Pyelogram) which requires roughly about 50ml of a special dye to be injected into the bloodstream that goes straight to the kidneys and helps outline any stone on a repeated X-ray. Computed tomography, a specialized X-ray, is by far the most accurate diagnostic test for the detection of kidney stones. Investigations typically carried out include:
TreatmentStones less than 5 mmin size usually will pass spontaneously, with diclofenacusually proving effective pain management. However the majority of stones greater than 6 mm will require some form of intervention, especially so if the stone is stuck causing obstruction and infection of the urinary tract. In many cases non-invasive Extracorporeal Shock Wave Lithotripsymay be used. Otherwise some form of invasive procedure is required; with approaches including retrograde ureteral, percutaneousnephrolithotomyor open surgery, and using laser, ultrasonicand mechanical (pneumatic, shock-wave) forms of energy to fragment stones. Secondary PreventionPreventive strategies include dietary modifications and sometimes also taking drugs with the goal of reducing excratory load on the kidneys:[{{fullurl:Template:FULLPAGENAME}}#endnote_AmFamPhysician]
More informationKidney stones are unrelated to gallstones. A high proteindietmay partly be to blame. Protein from meat and other animal products is broken down into acids. The most available alkaline baseto balance the acid from protein is calciumfrom the bones. The kidney filters from the blood and stores the calcium particles which have bonded with the acids. The more meatis eaten the more calcium is found in the kidneys. Over time, and when not properly removed, these particles bind together to form stones. One of the simplest fixes is to simply avoid protein. The French Renaissance essayist Montaignesuffered from kidney stones. British statesman Samuel Pepysalso suffered from kidney stones and was operated on, pre-anesthesia, to remove a large stone which he carried with him and used to try to persuade fellow sufferers to endure the painful surgery. His contemporary, John Wilkins, Bishop of Chester, could not face the prospect and died as a result. The author Isaac Asimovsuffered from kidney stones, and wrote about how his pain was treated with morphine, saying that he feared becoming addictedto morphine if he ever needed it again. Astronautsoften get kidney stones because of an increase in the amount of calcium in their blood due to a loss of bone density in zero gravity. Certain foods may increase the risk of stones: spinach, chocolate, peanuts, and cocoa; tomato juice, grapefruit juice, or apple juice; soda (acidic and contains phosphorus). Other drinks are associated with decreased risk of stones, including wine, coffee, lemonade and orange juice. Although it has been said that the diureticeffects of coffee and alcohol can result in dehydrationwhich is important for kidney stones sufferers to avoid, there are no data demonstrating an effect of either to increase the prevalence of stones. In fact, multiple studies have shown that alcohol, beer, and coffee drinkers are protected and have a lower incidence of stones. This protective effect is greater than the effect of simply drinking more fluid. It is important to recognize in this context that one of the recognized medical therapies for prevention of stones is thiazides, a class of drugs usually thought of as diuretic. These drugs prevent stones through an effect independent of their diuretic properties: they reduce urinary calcium. Nonetheless, their diuretic property does not preclude their successful use as stone preventive. Similarly, the data have consistently shown protective effects of alcohol and coffee. Caffeine does acutely increase urinary calcium excretion, another reason why coffee has often been proscribed for stone formers, but the epidemiologic evidence fails to support coffee restriction as an important therapeutic manipulation. See also
References
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de:Nierenstein es:Cálculo renal fr:Calcul rénal lt:Inkst? akmenlig? nl:Niersteen fi:Munuaiskivi sv:Njursten
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