what is a kidney stone

A kidney stone is a hard object made of minerals and salts that form inside the kidneys when urine contains more crystal-forming substances than the fluid in the kidneys. There are four types of kidney stones: calcium oxalate, uric acid, struvite, and cystine. Kidney stones can affect any part of the urinary tract, from the kidneys to the bladder. Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together. Common symptoms of kidney stones include severe pain in the lower back, blood in the urine, nausea, vomiting, fever, and chills. Passing kidney stones can be quite painful, but the stones usually cause no permanent damage if theyre recognized in a timely fashion. Depending on the situation, treatment may include pain medication, drinking lots of water, shockwave lithotripsy, uteroscopy, percutaneous nephrolithomy, or nephrolithotripsy. If a kidney stone becomes lodged in the ureters, it may block the flow of urine and cause the kidney to swell and the ureter to spasm, which can be very painful. In such cases, surgery may be necessary.