Urinary Stones (Urolithiasis, Nephrolithiasis)
Urinary stones (calculi) are hardened mineral deposits that form in the kidney. They originate as microscopic particles and develop into stones over time. Urinary stones may contain various combinations of chemicals. The most common type of stone contains calcium in combination with either oxalate or phosphate. A less common type of stone is caused by infection in the urinary tract. This type of stone is called a struvite or infection stone. Less common are the uric acid stone and the rare cystine stone.
Cause
Urinary stones usually arise because of a breakdown of a delicate balance. The kidneys must conserve water, but they must excrete materials that have a low solubility. These two opposing requirements must be balanced during adaptation to diet, climate and activity. The problem is mitigated to some extent by the fact that urine contains substances that inhibit crystallisation of calcium salts and others that bind calcium in soluble complexes. These protective mechanisms are less than perfect. When the urine becomes supersaturated with insoluble materials, because excretion rates are excessive and/or because water conservation is extreme, crystals form and may grow and aggregate to form a stone.
Symptoms
The first symptoms of a kidney stone is extreme pain. The pain often begins suddenly when a stone moves into the ureter, causing irritation or blockage. Typically, a person feels a sharp, cramping pain in the back and side in the area of the kidney or in the lower abdomen. Sometimes nausea and vomiting occur with this pain. Later, the pain may spread to the groin. If the stone is too large to pass easily, the pain continues as the muscles in the wall of the tiny ureter try to squeeze the stone along into the bladder. As a stone grows or moves, blood may be found in the urine. As the stone moves down the ureter closer to the bladder, a person may feel the need to ???? If fever and chills accompany ay of these symptoms, an infection may be present. In this case, a doctor should be contacted immediately.
Diagnoses
The urologist will order laboratory tests, including urine and blood tests. He or she will also ask about the patient’s medical history, occupation and dietary habits. If a stone has been removed, or if the patient has passed a stone and saved it, the lab can analyse the stone to determine its composition. CT scans and x-rays are the chief method used to diagnose kidney stones. Ultrasound can also be used to detect stones and urinary obstruction.
Treatment
Conservative – In asymptomatic patients a wait-and-see course may be recommended by the doctor. Many stones will become symptomatic and produce acute renal colic while travelling own the ureter some time in the future. The stones may enlarge and then become more problematic and difficult to treat.
Pain control – The severe pain of renal colic needs to be controlled by potent pain killers. Present to a doctor or emergency department as soon as possible to determine the cause of the pain.
EWSL – extracorporeal shock wave lithotripsy – shattering a stone with a shock wave produced outside the human body. There are several methods for producing an acoustical or ultrasonic “big bang” which is then focused from outside into the kidney and the kidney stone.
Ureteroscopy – this examination of the upper urinary tract is performed with either a rigid or flexible fibre optic device while the patient is under general anaesthetic. The scope is passed through the urethra and the bladder and then directly into the ureter. Smaller urinary stones in the lower ureter or bladder may be removed in one piece while larger stones can be broken down before removal.