Kidney stones

Figure 1. This photograph shows uric acid crystals in urine, when viewed using a microscope. Their birefringence under a polarizing microscope helps to discriminate uric acid crystals from other types of crystals, but biochemical analysis is required to reveal the chemical composition.

Kidney stones are common in Lesch-Nyhan disease. The main ingredient is usually uric acid. The stones develop as the kidneys try to concentrate the uric acid into the bladder for elimination in the urine. If there is not enough fluid in the system to constantly flush the uric acid and small crystals (figure 1) out in the urine, the stones enlarge.

The stones are dangerous because they can clog up the kidney or get stuck in the ureter, the tube the kidneys use to eliminate urine. When they get stuck they can block the flow of urine. An important warning sign in this situation is pain. The pain is usually severe, and felt mostly in the flank near the kidney, down into the lower belly and upper thigh region. The pain can come and go, depending on the location and movements of the stone.

If the urine can not get out, the kidney will have no place to dump its urine, and it will stop working. If the kidney is left in this situation for a long time, it will slowly degenerate. Most people have two kidneys and one will continue to work if the other is blocked. But if both kidneys are blocked, renal failure develops. This is a life-threating emergency.

Fortunately, the development of uric acid stones can be prevented in most situations by proper treatment. Even if stones develop, they can be removed if they are found. For more information, go to the secton on Treatment.