About kidney stones —

One of the most
common urological diseases.

What is urolithiasis?

Urolithiasis refers to the formation of stones in the urinary tract. These can occur in the renal pelvis, ureter, urinary bladder or urethra. Urinary stone disease is one of the most common complaints worldwide. It is considered a widespread disease. Its frequency is increasing in many countries. The reasons for this are changes in lifestyle and unhealthy eating habits, but improved medical diagnostics are also contributing to higher case numbers.
Modern ultrasound devices and CT procedures enable urinary stones to be detected more frequently. Treatment is usually minimally invasive. However, the recurrence rate is up to 50%.

 

Worldwide

115 M

cases in 2019.

Increase in kidney stone prevalence:

37%

in the last 20 years.

Recurrence occurs
in up to

50%

of kidney stone patients.

Residual fragments
increase the

RISK

of recurrence.

Fälle

Worldwide

115 M

cases in 2019.

Prävalenz

Increase in kidney stone
prevalence:

37%

in the last 20 years.

Rezidiv

Recurrence occurs
in up to

50%

of kidney stone patients.

Risiko

Residual fragments
increase the

RISK

of recurrence.

Kidney stones.
One of the most common uro­logical diseases.

The incidence of urinary stones varies between 1% and 20% worldwide. The prevalence is particularly high (over 10%) in countries with a high standard of living, such as Sweden, Canada or the USA. Some regions have recorded an increase of more than 37% in the last 20 years. There is an increasing link between kidney stones and the risk of chronic kidney disease (CKD). The Global Burden of Disease Study (GBD) recorded 115 million people with urolithiasis worldwide in 2019.

How are kidney stones treated?

A distinction is made between non-interventional (conservative) and interventional therapy. Interventional therapies include:

• Extracorporeal shock wave lithotripsy (ESWL or SWL)
• Percutaneous nephrolithotomy (PCNL or PNL)
• Ureterorenoscopy (URS)


ESWL is a non-invasive procedure. Shock waves are generated outside the body to break up kidney stones. The resulting fragments should be small enough to be excreted in the urine.

PCNL is a surgical method for the direct removal of kidney stones. It is particularly suitable for large stones. The procedure is performed under general anesthetic. A nephroscope is inserted through the skin directly into the kidney. PCNL is therefore more invasive than ESWL and URS and is associated with a higher risk of complications.

During the procedure, additional catheters are inserted into the bladder and ureter. Urine is drained from the bladder and, if necessary, contrast medium is instilled into the ureter to better localize the kidney stone. The stones are fragmented using laser or ultrasound and actively removed through the endoscope with a stone extraction basket. Small fragments are flushed out or left in the kidney to be passed spontaneously.

 

URS is a minimally invasive surgical procedure that can be used to perform an endoscopy of the ureter and kidney. Under general anesthetic, a ureterorenoscope is inserted via the urethral opening through the urethra and bladder into the ureter and kidney. The use of contrast medium makes it possible to better localize the kidney stone and identify anatomical abnormalities. The ureteroscope is equipped with a tiny camera that is used to see through the bladder into the ureter. The stone is either removed directly or shattered with a laser. The fragments are actively removed with a stone extraction basket.

After the procedure, a ureteral sheath and also a urinary catheter can be inserted to facilitate urine drainage - should the ureter be swollen as a result of the procedure. Both the ureteral sheath and the urinary catheter are removed shortly after the operation. The patients can leave the hospital if they are able to empty their bladder and there are no complications.

Risk factor:
Remaining Residual fragments

Residual fragments that remain in the kidney or ureter after interventional therapy can represent a nucleus for renewed stone formation. The term “clinically insignificant residual fragments (CIRF)” for residual fragments <4 mm is outdated and should no longer be used according to the current S2k guideline. The risk of recurrence within 5 years of the intervention is 21-59% of patients with residual fragments. Patients with struvite stones, also known as infectious stones, which are often caused by urinary tract infections, have a particularly high risk of recurrence.

Accordingly, the guideline recommends active stone removal of symptomatic residual fragments regardless of size and of asymptomatic residual fragments >4 mm as well as regular monitoring of fragments <4 mm. The smaller the residual fragments are, the higher the probability that they will pass spontaneously. However, there is evidence that even residual fragments <1 mm, also known as dust, do not always pass spontaneously and become larger.

With mediNiK® I can guarantee to my patients that they will be 100% stone-free after an operation.

Dr Michael Straub

Managing Senior Physician, Head of Endourology and Urinary Stone Centre, Klinikum rechts der Isar, Munich

How do kidney and urinary stones develop?

Our kidneys have – among other things – the important task of regulating the concentration of salts, electrolytes, water and the acid-base balance in the body by excreting these in the urine as required. Urine is formed in the kidneys, transported via the ureters to the bladder and excreted through the urethra.

Kidney stones occur when certain salts or uric acid are too highly concentrated in the urine. Small crystals form and grow into larger stones. The exact development process is complex and not yet fully understood. Risk factors for kidney stones are:

Lifestyle and diet

Pfeil
  • Excessive consumption of animal proteins and salt
  • Lack of chelating agents such as citrate, fibre fiber and alkaline foods

Metabolic disorders

  • Hyper­calciuria, hypocitra­turia, hyper­oxaluria, hyper­uricosuria
  • Gout (impaired uric acid metabolism)

Disorders of calcium metabolism

  • Primary hyper­parathy­roidism and other disorders of calcium metabolism

Urine compo­sition

  • Too many crystallisation crystallization promoters
  • Too few inhibitory substances

Low urine volume

  • Insufficient water absorption

Recurrent urinary tract infections

  • Changes in the urine pH value
  • Alkalisation by bacterial urease (e.g. Proteus mirabilis)

Genetic factors

  • Family Familial pre­dis­position
  • Monogenic hereditary diseases
  • Renal tubular acidosis

Anatomical anomalies

  • Defects of the medullary sponge kidney
  • Uretero-pelvic junction stenosis
  • Pyeloureteral duplication
  • Polycystic kidney disease
  • Horseshoe kidney

Other factors

  • High blood pressure
  • Overweight
  • Climate change and geographical conditions

Intestinal diseases

  • Inflammatory bowel diseases
  • Intestinal malabsorption
  • Lack of oxalate-degrading intestinal bacteria

Certain medications

  • Indinavir (Crixivan)
  • Sulfonamides (sulfadiazine)
  • Certain diuretics
  • Ceftriaxone (in high doses over a long period of time)
  • Diuretics that are poorly soluble and favour the formation of stones

Prevention of urinary stone disease

To prevent a recurrence of the stone disease, the doctor first carries out a risk assessment, which assigns the patient to either the low-risk or high-risk group. This is evaluated on the basis of the composition of the urinary stones and the basic diagnostics (diet, comorbidities, medication, family history, laboratory blood tests, etc.). In addition to general urinary stone metaphylaxis as a basic therapy, high-risk patients also require stone-specific prophylaxis depending on the patient’s biochemical risk profile.

The following general measures (basic therapy) are recommended for all urinary stone patients regardless of the risk group:

Adjustment of fluid intake

Increase the amount you drink to 2.5 to 3 litres a day: This leads to increased flushing of the urinary tract, shortens the urinary transit time, impedes crystal formation and flushes out pathogenic germs.

Suitable drinks: Kidney, bladder and fruit teas, mineral waters low in minerals, apple juice (urine-neutral); bicarbonate-rich medicinal waters, citrus juices (urine alkalizers).

Unsuitable drinks: Avoid caffeinated coffee and black tea (max. 2-3 cups/day), alcohol, sugary fruit drinks, soft drinks and cola (these increase the risk of calcium oxalate stone formation).

Dietary adjustment

Protein: 0.8 g/kg body weight, preferably vegetable. Reduce animal protein, as it increases calcium excretion and thus the risk of stone formation.

Purines: Reducing purine-rich foods (offal, meat, fish, pulses) increases uric acid excretion and the risk of stone formation.

Calcium: Adequate intake through low-fat dairy products and calcium-rich mineral water. Low calcium intake increases the risk of calcium oxalate stone formation.

Magnesium: Reduces oxalic acid excretion and promotes the solubilization of calcium oxalate.

Lifestyle adjustment

Physical exercise: Physical activity causes tiny urine crystals to be excreted more efficiently. In addition to sporting activities, changes in everyday habits, such as taking the stairs or cycling, also contribute to this.

Achieving a normal weight: Overweight favors the development of urinary stones. Therefore, if you are overweight, you should endeavor to lose weight.

Stress limitation: Stress is also a risk factor for the renewed formation of urinary stones. Relaxation techniques can reduce the likelihood of recurrence.

For high-risk patients

The following stone-specific measures are recommended in addition to basic therapy:

  • No alcohol
  • Little meat, fish and sausage
  • Lacto-vegetarian diet: Vegetables, cereals, potatoes, fruit, dairy products

  • Therapy with a suitable antibiotic

  • For adults, fluid intake of more than 3.5 litres per day
  • Alkalization therapy