Kidney
stones are hard objects formed by crystals – usually of mineral salts, particularly calcium, but including others such as potassium –found in the kidney. Depending upon where they are in the kidney, they will cause more, or less, discomfort. If the stone is in the solid part of the kidney, and it isn’t particularly large, it is unlikely to give any symptoms at all and its presence might be quite unsuspected. If, however a stone gets stuck at the entrance of the tube joining the kidney to the bladder (the ureter) there can be agonising pain – renal colic. This truly dreadful pain is felt in the side part of the back, the loin, on the affected side and the pain may be transmitted into the abdomen and down into the groin and, in the male, into the testicle. The pain is sometimes associated with vomiting and obvious blood in the urine. This constitutes a medical emergency and can result in severe damage to the kidney from backpressure, the "blown kidney" or hydronephrosis. This is particularly true of the large jagged stones known as "stag horn stones". Similar symptoms can be caused if the stone gets stuck in the ureter –ureteric colic. Renal and ureteric stones associated with a fever constitute a highly dangerous situation and can lead to septicaemia. Kidney stones can be caused by illness where the blood levels of calcium are high and by infections in the kidney. Chronic gout (see Gout) can cause kidney stones which are largely composed of urates, the same substances that make gouty joints swollen and painful. All stones can be made worse when the patient is dehydrated and the blood salts, and the urine, become concentrated. This may be due to a debilitating illness or, simply, inadequate fluid intake. Moslems with renal stone problems are given dispensation during Ramadan because the restricted fluid and dietary intake may bring on an acute attack.
Renal colic from a kidney stone is a medical emergency and a doctor must be consulted. The appropriate analgesic, usually by injection, will be given. Follow up will involve investigation of the kidney, which usually entails blood tests, ultra sound and, sometimes, special X-rays. A cause for the stone formation will be sought. Most usefully, if the stone is passed and retrieved, it can be analysed in the pathology lab. 70% of stones are found to be composed of calcium oxalate. Oxalate rich foods should therefore be avoided. These include chocolate, nuts, tea, spinach, strawberries – and the one everybody knows – rhubarb. Reducing calcium intake might help. This may be achieved by cutting down dairy products and red meat and increasing the amount of ingested bran. If potassium salts are implicated a reduction of fruit, particularly bananas, and some vegetables may be advised. If the stone is found to be made of urate, then, almost certainly, gout is involved and the patient should take medication to help remove excess urate from the body. |
