Some people pass small kidney stones without even noticing, but larger stones often make the sufferer double up in extreme pain, an independent German health advisory agency says. Hard deposits often consisting of calcium salts, kidney stones can form in people who either don’t drink enough fluids or lose too much fluid, for example by perspiring heavily, points out the Cologne-based Institute for Quality and Efficiency in Health Care (IQWiG) on its web portal for patient information. A salt-rich diet and genetic predisposition are also possible contributing factors. A mild twinge in the kidney region can be the first sign of a kidney stone. Many affected persons have no symptoms, however. Smaller stones are passed out without the sufferer noticing them. But often, when a stone enters a ureter – the duct through which urine passes from a kidney to the bladder – it makes itself felt with pain ranging in intensity from mild discomfort to pain so severe that you barely move! The pain can occur below the ribs, in the lower abdomen or back, depending on where the stone is at the moment. Other possible symptoms are painful or frequent urination. It’s important that someone who has developed kidney stones pinpoint the cause so as to help prevent their recurrence. According to the IQWiG, in Germany between 1 and 2 percent of the population develop kidney stones at one time or another. A physician generally detects the presence of kidney stones with an ultrasound scan. While smaller stones usually pass out of the body on their own, larger ones have to be removed surgically, the treatment depending on their size and position, the IQWiG points out. Medical intervention is also necessary if a stone doesn’t pass out of the body within four weeks, there is renal colic – a type of intense pain that typically begins in the abdomen – or complications arise! Left untreated, kidney stones can constrict or block the ureter and lead to an infection.