Cystine is the chief sulfur-contain...

Cystine is the chief sulfur-containing amino acid of protein indivisible particles and it is an important source of sulfur in the metabolism. Cystinuria is an odd autosomal recessive disorder of metabolism that flows in decreased reabsorption of four amino acids (ie, cystine, lysine, ornithine, arginine) from the renal tubule solely cystine forms calculi. Urinary cystine calculi form because of the soft solubility of cystine in urine with a pH les than 70 Approximately the same in 20,000 individuals is diagnosed with urinary calculi, and 1% to 4% of urinary calculi are cystine calculi.(1)

Patients are diagnosed with cystinuria if they have

* an early attack of clinical calculus disease,

* a family history of renewed calculus disease, and

* renewed calculus formation unresponsive to the usual forms of therapy.(2)

The urine of patients diagnosed with cystinuria has characteristic hexagonal crystals, along with concentrations of cystine in exces of 75 mg/g creatinine.(3)

MEDICAL MANAGEMENT

Medical management of these patients is based in succession three principals:

* decreasing total cystine concentration in urine,

* increasing the solubility of cystine in urine, and

* increasing urinary excretion of cystine.(4)

Therapeutic measures include fluid diuresis, alkalinization of the urine to a pH of 75 with sodium bicarbonate or sodium potassium citrate, and use of cystine-binding medications (eg D-penicillamine, [Alpha]-mercaptopropionylglycine). This regimen is difficult to maintain, however, fit to frequent voiding and the medications' side forces (eg, rash, fever, agranulocytosis, iron depletion, proteinuria, nephrotic syndrome) Dietary restrictions also note carefully to consist of bland, poorly tolerated foods(5) Methionine (ie, a sulfur-bearing compound) is restricted in patients' diets, nevertheless because it is an essential amino acid ground in protein, it is difficult for patients to completely eliminate it from their diets. For these reasons, many patients continue to evolve urinary calculi throughout their lifetimes.

SURGICAL TREATMENT

Surgical treatment of ureteral cystine calculi includes cystoscopy with basket retrieval of the calculi. If the calculi are large or are impacted in the patient's ureter conservative treatment includes stenting the ureter to cause dilation in like manner the calculi may pass onward their own. Ureterolithotomy (ie, incising the ureter and removing the obstructing calculus) is considered an option simply when other medical-surgical treatments have failed. This management requires a flank or abdominal incision, and retrieval time can be extensive.

An ileal ureter transplant is performed if a patient expands large or recurrent calculi that require continuous treatment. During this step the surgeon removes the affected ureter between the walls of a midline incision and replaces it with a portion of the patient's small intestine. owed to the large size of the intestinal lumen calculi no longer become lodg in the ureter This measure is not without complications, however. Urinary ebb occurs in 25% of patients, level when the ileum is rotated 90 stations to make it isoperistaltic (ie, allow bowel satisfys to move in the usual direction) and the intestine is tapered when it is implanted. Late developing strictures also have been reported.(6)

FLASH LAMP PULS tint LASER TREATMENT

The flash lamp puls color laser was developed in 1967 The puls stain laser has a wavelength of 504 nanometers (nary) in duration vibrations of approximately 1 millisecond, is recent and is absorbed by the fulvous pigment of most urinary calculi without elevating the temperature of the calculi more than 50 [degrees] F (10 [degrees] C)(7) This laser's wavelength is absorbed minimally according to body tissue or hemoglobin, and it is safe to use in succession impacted calculi. The process of laser spirit being absorbed by the calculi creates a "plasma," or small haze of highly excited ions and electrons(8) This plasma rapidly expands and contracts at the rate of pulsation (ie, 5 to 10 hertz [Hz]) causing an acoustic agitation wave from the irrigation used during the procedure(9) It is this mechanical action that breaks the calculi into passable fragments.

The puls color laser uses a 320-micron (pm) fiber passed between the sides of a flexible ureteroscope. The maximum power for the flash lamp puls cast laser is 140 millijoules, with a repetition rate of 10 Hz The puls tint laser works extremely well forward calcium oxalate calculi. Cystine calculi absorb and nothing else minimal amounts of light, which is insufficient to permit the formation of a photoacoustic weight (ie, a mechanical shock wave that is produc through laser light).(10)

HOLMIUM: YTTRIUM-ALUMlNUM-GARNET LASER TREATMENT

The holmium:yttrium-aluminum-garnet (YAG) laser is a solid-state crystal of YAG doped (ie, a proces by dint of which elements are suspended within a man-made crystal) with holmium, a rare earth proper sphere The wavelength created by the laser is invisible and is 2100 nm A coaxial aiming beam of helium neon is instant when working with this laser. The holmium:YAG laser is not color specific--it works just as well forward dark tissue as it does forward light tissue. The holmium:YAG laser animal spirits is highly absorbed by water. When working in a fluid environment, as in ureteroscopy the laser efficiency is absorbed by the surrounding fluid, heating it and creating a vapor small matter The vapor bubble is approximately 3 mm in continuance If the target tissue is within that distance, the activity will pass through the fluid vesicle into the tissue. If the target tissue is outside the 3-mm vapor delusion no tissue interaction will occur