Kidney stones (nephrolithiasis)

Description

Kidney stones (also known as renal gravel) are deposits in the renal tubules, pelvis and urinary tract.

These deposits are formed from urine, more specifically from the calcium salts it contains, or from uric acid, magnesium ammonium phosphate or cystine.

Kidney stones are a common condition, occurring almost twice as often in men as in women. Most of those affected are found between the ages of 30 and 60.

By increasing the concentration of urinary components, crystals form which, due to their small size, do not initially cause any discomfort and can pass through the draining urinary tract without any problems. However, if they increase in size over time, they can block urinary tracts when they break loose and produce symptoms such as painful renal colic.

A variety of different diseases and circumstances can result in deposits. In general, anything that increases urine concentration promotes kidney stones.

Metabolic disorders

• Hyperthyroidism
• Hyperparathyroidism
• Boeck's disease (sarcoidosis)
• Cystinuria
• Primary hyperoxaluria

Other promoting factors:

• Kidney disease
• Intestinal diseases
• High temperatures and heavy sweating
• Dehydrating foods (e.g. rhubarb, asparagus)
• Too little fluid intake
• Congestion of urine (e.g. malformation or narrowing of the kidneys or urinary tract)
• Taking calcium or vitamin D (calciferol) supplements
• Medication e.g. acetazolamide, sulfonamides, triamterene, indinavir, ASS
• Frequent urinary tract infections
• Weight loss
• Frequent occurrence of kidney stones within the family

Kidney stones can only cause pain when they reach the urinary tract.

While small stones flow away with the urine and usually only cause a slight stabbing pain when urinating, those with a diameter of about 0.5 cm or more lead to renal colic. Severe pain and possibly also inflammation of the irritated urinary tract are the result. The stone discharge can take hours or even a few days.

The following accompanying symptoms cannot be ruled out in renal colic:

• Stinging, cramping and pain from the back and lateral lower abdomen to the groin and genital area.
• Nausea and vomiting
• Reflective intestinal obstruction due to severe pain
• Decreased urine volume
• Renal pelvic inflammation
• Hematuria (blood in the urine)

Chronic kidney stones that cannot migrate on their own are more noticeable by a dull squeeze in the area of the kidneys. They can cause bacterial infections and lead to complications. Consequential diseases such as urinary tract infections or urosepsis (urinary fever), whereby bacteria from the urinary tract pass into the bloodstream, are possible.

In particularly severe cases, kidney tissue is destroyed and so-called shrunken kidneys develop.

Kidney stones can be detected quickly using imaging techniques. A combination of ultrasound of the urogenital tract and X-ray of the kidneys and urinary tract enables a clear diagnosis. Alternatively, spiral CT (special computer tomography) or urography (less common, as contrast medium is required) can be used.

Depending on the case, a cystoscopy or scintigraphy may also be necessary.

If kidney stones have been diagnosed, urine should be passed into a sieve to at least partially collect the stones. They can then be examined in a laboratory to determine the exact cause of the stones and to take appropriate measures to prevent them from forming again.

Additional examinations

If there is any suspicion of kidney disease, blood and urine are examined for infections, metabolic disorders and to assess kidney function. In order to be able to calculate the daily excretion of individual substances, urine must be collected at least once over a 24-hour period.

Flushing out

In the case of renal colic, an attempt is made to flush out the stone. Sufficient fluid intake, antispasmodic medication and movement (e.g. hopping) help here.

With stones larger than 7 mm in diameter, spontaneous expulsion is practically impossible. Further treatment depends, among other things, on the components, exact location and size of the stone.

• Litholysis: Medicinal dissolution of the kidney stone
• ESWL (Extracorporeal Shock Wave Lithotripsy): Targeted shock waves disintegrate deposits
• PCNL (Percutaneous Nephrolitholapaxy): In the course of a minimally invasive procedure, kidney stones are crushed and removed.
• Ureterorenoscopy: Surgical procedure for ureteral stones. Instruments for disintegration and removal are inserted into the ureter via the urethra and bladder. To facilitate removal, a stent (place-holding catheter) may also be inserted into the ureter for several days.
• Snare extraction: (high risk of injury, only in exceptional cases!): an attempt is made to extract the stone with the aid of a snare.
• Open surgery: in rare cases, a kidney stone must be removed by open surgery.

Kidney stones can always recur, but the risk can be minimized by appropriate prophylaxis.

Complications cannot be ruled out. They can include inflammation of the renal pelvis, urosepsis (blood poisoning due to urinary tract inflammation) or narrowing of the urinary tract, and in rare cases even acute kidney failure.

• Sufficient fluid intake
• Low-salt and low-fat diet
• At least 5 portions of vegetables and fruit daily (contain ingredients that inhibit stone formation)
• If you have a tendency to stones containing oxalic acid, you should avoid cocoa, rhubarb, spinach, nuts, black and green tea.

The above guidelines are especially valid for people who have already had kidney stones. Without a consistent change in diet and, if necessary, drug treatment, 50% of patients will develop the disease again.

Medications can be given in accordance with previous kidney stones, which change the composition of the urine and thus prevent the formation of new crystals.