Common Kidney Diseases (4): Kidney Stones

ARE your kidneys OK? Today, I shall take us through another kidney disease condition, the ‘Kidney Stones (Nephrolitiasis or Urolithiasis). I will present a hypothetical story to enable readers follow the discussions.

What are Kidney Stones?
Kidney stones are one of the most common disorders of the urinary tract. They are one of the most painful disorders afflicting humans. Scientists have found evidence of kidney stones in an Egyptian mummy estimated to be more than 7,000 years old! Most kidney stones pass out of the body without any intervention. Cases that cause lasting symptoms or other complications may be treated by various techniques, most of which do not involve major surgery.

A kidney stone develops from crystals that separate from urine and build up on the inner surfaces of the urinary tract. Normally, urine contains chemicals that prevent or inhibit the crystals from forming. These inhibitors do not seem to work for everyone, hence some people form stones. If the crystals remain tiny enough, they will travel through the urinary tract and pass out of the body in the urine without even being noticed. Kidney stones may contain various combinations of chemicals. The most common type of stone contains calcium. These chemicals are part of a person’s normal diet and make up important parts of the body, such as bones and muscles. 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. Much less common are the uric acid stone and the rare cystine stone.

What Causes Kidney Stones?
Men tend to be affected more frequently than women. White people are more prone to kidney stones than black people. Kidney stones strike most people between the ages of 20 and 40years. Once a person gets more than one stone, he or she is more likely to develop others. While certain food items may promote stone formation in people who are susceptible, it is not true that eating any specific food causes stones to form in people who are not susceptible. A person with a family history of kidney stones may be more likely to develop stones. Urinary tract infections, some kidney disorders such as cystic diseases, and metabolic disorders are also linked to stone formation.

In addition, certain hereditary diseases are associated with formation of kidney stones. Other causes of kidney stones are hyperuricosuria (a disorder of uric acid metabolism), gout, excess intake of vitamin D, and blockage of the urinary tact. Certain calcium-based antacids may increase the risk of forming kidney stones by increasing the amount of calcium in the urine. Calcium stones may also form in people who have a chronic inflammation of the bowel or who have had an intestinal surgery. As mentioned above, cartain stones can form in people who have had a urinary tract infection.

What are the symptoms of Kidney Stones?
Usually, the first symptom of a kidney stone is extreme pain. The pain often begins suddenly when a stone moves in the urinary tract, causing irritation or blockage. Typically, a person feels a sharp, cramping pain at 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 narrow 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 urinate more often or feel a burning sensation during urination. If fever and chills accompany any of these symptoms, an infection may be present. In this case, a doctor should be contacted immediately.

How are Kidney Stones Diagnosed?
Sometimes “silent” stones are found in x-rays taken during a general health exam. These stones would likely pass unnoticed. More often, kidney stones are found in an x-ray or during ultrasound examination done on someone who complains of blood in the urine or sudden pain. Blood and urine tests help detect any abnormal substance that might promote stone(s) formation. The doctor may decide to carry out further tests as necessary.

How are Kidney Stones Treated?
Fortunately, most stones can be treated without surgery. Most kidney stones can pass through the urinary system with plenty of water to help move the stone s along. In most cases, a person can stay at home during this process, taking pain medicine as needed. The doctor usually asks the patient to save the passed stone(s) for testing. People who have had more than one kidney stone are likely to form another. Therefore, prevention is very important. A simple and most important lifestyle change to prevent stones is to drink more liquids—water is best. A recurrent stone patient should try to drink enough liquids throughout the day to produce at least two litres of urine everyday. Patients with too much calcium or oxalate in the urine may need to eat fewer foods containing such (see below). However, some patients who have high levels of oxalate in their urine may benefit from extra calcium in their diet. Patients may be told to avoid food with added vitamin D and certain types of antacids that have a calcium base. Patients who have very acidic urine may need to eat less meat, fish, and poultry. These foods increase the amount of acid in the urine.

The doctor may prescribe certain medications to prevent calcium and uric acid stones. These drugs control the amount of acid or alkali in the urine, key factors in crystal formation. Another way a doctor may try to control calcium stone formation is by prescribing water tablets. These drugs reduce the amount of calcium released by the kidneys into the urine. Some type of surgery may be needed to remove a kidney stone if the stone does not pass after a reasonable period of time and causes constant pain, is too large to pass on its own, blocks the urine flow, causes on-going urinary tract infection, damages the kidney tissue or causes constant bleeding, or has grown larger (as seen on follow-up x-ray studies).

Until recently, surgery to remove a stone was very painful and required a lengthy recovery time (4 to 6 weeks). Today, treatment for these stones is greatly improved. Many options exist that do not require major surgery. Persons prone to forming calcium oxalate stones may be asked by their doctor to cut back on certain foods such as apples, beer, chocolate, coffee, ice cream, milk, oranges, pineapples, spinach, tea, vitamin C and yoghurt. Persons should not give up or avoid eating these types of foods without talking to their doctor(s) first. In most cases, these foods can be eaten in limited amounts.