Cystine stone

Cystine stones , also called cystine stones , are a rare form of urinary stone .

Cystine stones are usually rounded or shaped like a spout, adapted to the renal pelvis. They have a waxy, smooth surface and are similar to milk glass. In terms of color, however, they are more yellowish.

Cystine stones are very rare and are caused by an inherited metabolic disorder. They make up only 1 to 3 percent of the urinary stones.

Emergence

Cystine incurred in the rare autosomal - recessive inherited cystinuria . In healthy individuals, concentrations of cystine develop in the urine that do not exceed solubility . In homozygous patients, however, this can be exceeded many times over.

This disorder increases the amount of amino acids excreted in the urine. In contrast to healthy people who excrete around 40 to 80 mg of cystine per liter of urine, the excretion of those affected is over 1000 mg / l.

In contrast to the other three affected amino acids in cystinuria ( arginine , lysine and ornithine ), only cystine is sparingly soluble. Therefore, only cystine stones develop in those affected .

treatment

Due to the internal structure of the stone structure, cystine stones are not porous and can be very poorly or not at all with the help of fragmentation techniques such as B. the shock wave therapy ESWL are treated. They are not hard, but rather "rubbery", which makes treatment difficult. As a rule, surgical procedures are required to remove the stones:

Percutaneous nephrolitholapaxy - a puncture needle is used to drill a thin canal from the outside of the kidney . An optical instrument is inserted through the canal, the kidney stones are crushed and removed.
Ureterorenoscopic stone removal - this surgical method is used for ureteral stones. A rigid or flexible, thin tube is inserted with an optical instrument (similar to a cystoscopy) via the urethra into the bladder and further into the ureter. Various devices for breaking up and removing ureteral stones can be inserted through the working channel of the optical instrument. These can be ultrasound, laser, special probes or forceps. Sometimes a catheter is also left in the ureter as a placeholder (stent or ureteral splint) for a few days in order to facilitate the natural removal of further stone fragments.
Loop extraction - due to the high risk of injury, it is only performed in exceptional cases today. A noose is inserted through the urethra and the doctor tries to pull the stone out. The method is only used when the stone is in the lower third of the ureter. This type of treatment is no longer mentioned in the EU directives, as the risk of injury to the ureter from sharp stones is relatively high.

As a last resort, the stone must be removed by open surgery.

prophylaxis

The underlying disease cystinuria should be controlled as effectively as possible. In addition, the supply of the amino acids cysteine and methionine is minimized. The build-up of cystine from cysteine can be reduced by taking vitamin C regularly. In return, however, the urine should be alkalized (solubility product is improved) and sufficient amounts of water should be consumed (e.g. with at least two liters of bicarbonate-rich mineral water per day).

Web links

Patient guide cystine stones ( Memento from March 17, 2004 in the Internet Archive ) of the University of Zurich

This text is based in whole or in part on the entry Zystinstein in Flexikon , a wiki of the DocCheck company . The takeover took place on June 19, 2007 under the then valid GNU license for free documentation .