Urolithiasis – (kidney stones / urinary stones / bladder stones)

About 5–10% of all people form urinary stones once in their lifetime. The ratio of men to women is about 3:1. In addition to gender, age is also a risk factor. In old age, urinary stones occur more frequently (age peaks 40 to 50 years of age) while they are rather rare in children (1–5% of stone patients).

In addition to localization, urinary stones can also be classified based on their chemical components. More than 80% of the urinary stones consist of calcium salts (calcium oxalate or calcium phosphate). The frequency of so-called infection stones, which consist of magnesium-ammonium sulfate and /or carbonapatite and are often associated with infections, decreases due to increasing prophylaxis in Western countries. The occurrence of uric acid stones, on the other hand, increases due to over- and malnutrition.

Causes:

• Over- and malnutrition
• (Hereditary) Metabolic defects
• Exsikcosis (dehydration)
• Lack of exercise
• Idiopathic (without discernible cause)
• Anatomical abnormalities of the urinary tract
• Drug-induced (calcium, vitamin D, vitamin C >4 g/day)

The basic principle of stone formation is the crystallization of dissolved substances in the urine. We all excrete these substances in the urine. It becomes problematic when these are present in increased concentrations. This leads to the aggregation of the substances and to the formation of crystals. This also has no disease value, as long as the crystals are small enough and can continue to be excreted in the urine. However, if other risk factors, such as lack of exercise, lack of fluids, inadequate nutrition, etc., are added, the crystals continue to accumulate and form stones. These are then often deposited in the urinary system, can no longer be excreted and lead to urolithiasis.

Inhibitors that prevent the crystallization of most stones are:

• Magnesium, citrate
• Diluted urine by sufficient fluid

Promoters that promote crystallization are:

• Oxalate, calcium
• Concentrated urine due to lack of fluid

Types of stone:

• Calcium Oxalate Stones: (CaOx) 80-90% of all urinary stones
• Uric acid stones: about 8-10% of all urinary stones
• Infectious stones/ struvit stones: about 5-7% of all urinary stones
• Calcium phosphate stones: about 4-6% of all urinary stones
• Cystine stones: about 0.5-1% of all urinary stones

Uric acid stones are often the result of unbalanced diet and lack of exercise. On the one hand, the one-sided diet, which today is often very fat- and meat-heavy, often leads to increased concentrations of substances that act as stone formers. One example is hyperuricosuria (increased levels of uric acid in the urine), which results from high meat consumption and promotes the formation of uric acid stones. On the other hand, an unbalanced diet leads to hyperacidity of the body. As a result, the environment in the urine also shifts into the acidic acidic pH range (<6). For most types of stone, the more acidic the urine, the worse the various stone-forming substances are soluble. This is called the “acid rigidity” of urine. Consequently, a low urine pH favors the formation of urinary stones.

Diagnosis

The diagnosis of urolithiasis is usually based on clinical symptoms and imaging techniques. As a rule, urolithiasis can already be detected on ultrasound. Even if the stone itself cannot always be identified, the side effects, such as a urinary congestion and an enlarged renal pelvis, are usually clearly visible. For exact stone localization, further methods such as X-ray or CT can then be used.

Urine test strips can be used, among other things, to detect the specific gravity and hematuria, i.e. the presence of blood components in the urine. Furthermore, the pH value can be determined. A summary of the parameters cannot reliably diagnose urolithiasis, but the parameters are important points of reference, also with regard to the prophylaxis of urinary stones.

Different crystals can be made visible in the urine sediment. In the collective urine, lithogenic substances (calcium, uric acid, oxalate, phosphate, cystine, dihydroxyadenine (DHA)) can be quantified. Previous stones can be examined by infrared spectroscopy.

Prophylaxis:

• Nutrition with little animal proteins and little salt
• Drink a lot
• Avoid drinks and food that acidify the urine (e.g. apple juice, beer)
• Weight normalization