Nephrolithiasis

Introduction

A urinary calculus disease is the most common problem of urinary system after urinary infections and prostatic diseases. The incidence of kidney stones is reported to have been increased over the two-three decades. The cause of this increase is uncertain but considered to be related to changes in nutritional regimen and decrease fluid intake.

How is a kidney stone (calculi) formed?

The kidneys function as a filter system of the body. The blood is constantly filtered to absorb useful substances and excrete unwanted substances in the urine. A kidney stone is usually formed when substances in the urine become highly concentrated. The salts and minerals in the concentrated urine are precipitated in crystals to form a kidney stone over time in the units called tubules located in the kidneys. These crystals join together in time to form a stone.

Nephrolithiasis occurs when calcium (hypercalciuria), oxalate (hyperoxaluria) or uric acid (hyperuricuria) levels are high in the urine in addition to decreased citrate that prevents crystals from adhering together, or when the urine is more concentrated due to inadequate fluid intake. This process resembles a grain of sand that gets into an oyster and transforms into a pearl. The size of the stones varies between a grain of rice and a tangerine.

What are the complaints related to kidney stones?

Most of the kidney stones are asymptomatic and identified during radiological studies performed for other reasons. If the stone is large, it can cause obstruction and swelling of urethra, resulting in pain and infection. If the stone moves and travels down the ureter, which is located between the kidneys and the bladder, the whole kidney will become swollen, resulting in a very severe pain called renal colic. This pain usually aggravates at 5 to 15-minute intervals then diminishes. The pain initially arises from the related side where the ribs end and radiates to the umbilicus. The location of the pain changes towards the groin, bladder, or genital organs as the pain radiates down the kidney. Additional complaints such as nausea, vomiting and abdominal distension may present with the pain.

How is a kidney stone diagnosed?

Some part of kidney stones are incidentally discovered during routine check-ups, or when investigating another pathology. Other part of kidney stones is identified when investigating the cause of side pain, recurrent urethritis, or haematuria (blood in the urine). The following radiological methods are used to diagnose the stone.

Direct urinary system graphy (DUSG)

Most of the opaque kidney stones are visible on this graphy taken by X rays. This method is also used to monitor changed location of the stone in the ureter over time.

Ultrasonography

In this method, the data obtained using high frequency sound waves to monitor internal organs is converted into an image with a computer. Although it is a safe method because no X rays are used, it may fail to display small stones located in the ureter in particular.

Intravenous Pyelogram (IVP)

This method is used to determine the exact location of the stone in the ureter and the degree of obstruction it has caused. An injection of contrast medium is given to a patient into the brachial vein in order to monitor its travel along the kidneys, ureter, and bladder using a series of urinary system radiographs taken. This method provides information both on function and anatomy of the kidneys. It is not a method of choice because it often requires intestinal enema, and the procedure takes long, instead computed tomography is used.

Spiral Computed Tomography (CT)

It has become a standard method to evaluate kidney stones at many modern centers. It can be performed within minutes, is able to identify even millimetric stones; requires no intestinal preparation or contrast medium. Main disadvantages are that it is an expensive method and performed using X rays.

Do the patients who are diagnosed with kidney stone need to have other tests?

Studies show that the patients who fail to take measures against stone formation are likely to redevelop a stone in five years with a rate of about 50%. To prevent this, several evaluations are made and treatments are delivered to avoid new stone formation in patients who have recurrent stones; whose stones are metabolically activated (existing stone grows in the last 1 year, a new stone is formed, and a kidney stone is passed), and in pediatric patients; in those with a family history of kidney stone; in the presence of a disease that may cause stone formation such as chronic intestinal diseases, gout arthritis. A 24-hour urine is collected for this study called metabolic evaluation then the levels of calcium, uric acid, citrate, and oxalate are assessed in the urine. At the same time, a blood sample is collected to assess blood levels of calcium, inorganic phosphate and parathormone.

What are the factors that increase the risk for stone formation?

Inadequate Fluid Intake

The concentration of minerals that cause stone formation will be increased in case of inadequate fluid intake. Therefore, the risk for stone formation of those who live in hot climate and work at hot environments, e.g. industrial kitchens, increases.

Family History and Personal History

The risk for stone formation of those who have a family history of stone is high. The risk of a patient, who has developed a stone, for developing a second stone in 5 years is around 50-60%.

Age, Gender, and Race

Nephrolithiasis mostly occurs between the ages of 30 and 50. The incidence of nephrolithiasis is more common in men and white race.

Some Diseases

The risk for stone formation increases with some rare diseases such as renal tubular acidosis, gout, and cystinuria.

Diet

The risk for stone formation increases with diets containing high animal protein and low fibers. In addition, high use of salt is proved to be associated with stone formation.

Less Activity or Physical Inactivity

Osteoporosis occurs in sick-abed and in patients who remain physically inactive for a long time, which increases the risk for stone formation due to increased calcium concentration in the urine.

What kind of problems can occur if an identified kidney stone is left untreated?

If a stone is detected in the calyx, a cuplike structure in the kidney, this does not usually cause a problem. However, if it grows in place, or detaches and enters in the ureter, it interferes with urinary flow, resulting in pain, hemorrhage, and inflammation. It may lead to permanent kidney damage depending on the degree of obstruction.

How is a kidney stone treated?

Medical Treatment

The stones up to 5 mm can pass on its own with the help of medication and adequate fluid intake. Larger stones are unlikely to pass on their own.

ESWL (Extracorporeal Shock Wave Lithotrispy)

It is a method often used to treat kidney stones. The shock waves are focused on the stone to break it into small pieces without a surgical intervention then these smaller stones are expected to excrete in the urine. To diminish the pain during the procedure, mostly sedatives and sometimes a light anesthesia is delivered to the patient. Complications following an ESWL include blood in the urine, and rarely hemorrhage on the kidney or adjacent organs. The patient may feel uncomfortable and experience pain during excreting the small stones in the urine.

Percutaneous Nephrolithotripsy (PNL)

It is used when it is not possible to break up the stone with ESWL, or when the stone is larger. A small puncture is made on the side wall of the abdomen to insert a tube 1 cm in dia. inside the kidney under general anesthesia in the operating theatre. The stone is crushed by a device with a special optic and the stone-breaking devices then the stone fragments are removed through the tube. The patient will need to stay in the hospital for 2-3 days after the procedure.

Rigid Ureteroscopy

A urethroscope is a device 2.5-3 mm in dia. with a light at the tip, and working canal and lens. The exterior urinary tract and bladder are passed to enter in the ureter with a rigid urethroscope. The stones in the lower ureter near the bladder are crushed by Holmium laser.

Flexible Ureteroscopy

A flexible urethroscope is a wire-like device that has a same diameter and working principle as the other urethroscopes. A flexible urethroscope is used to break and treat stones both in the upper ureter and in the calyx, a cuplike structure in the kidney, as it can be turned in various directions and degrees. A general anesthesia is usually delivered for an ureteroscopic procedure.

The patients are usually discharged on the same day or the following day of an ureteroscopic procedure

Can formation of a kidney stone be prevented?

Growth of existing stones can be delayed, or the risk for a new stone formation can be reduced by changing several things in the life style. The recent scientific studies have demonstrated that previous diets including strict restrictions are not realistic, and the patients do not comply with such restrictions. An up-to-date diet to prevent stone formation is simplified and summarized below.

  • You need to drink 2.5 liters of fluid a day, mostly water. This volume should be increased in hot seasons and regions where sweating mostly occurs.
  • Animal proteins, especially offal meals, should be eaten less and at one meal is possible.
  • You need to use less salt.
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The information on this website is not intended to replace any medical advice given by physicians with access to your detailed medical history.