Chemical analysis of a kidney stone is performed to identify the chemicals that make up a kidney stone, to treat any underlying disease that may have caused the stone to form. The information obtained from the analysis is also used to determine the most effective methods to reduce the likelihood of a new stone forming.
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About 5% of women and 12% of men will develop kidney stones at some point in their lives. About 80% of stones are composed of calcium oxalate (CaOx) and calcium phosphate (CaP), 10% of stones are composed of magnesium ammonium phosphate (struvite) formed during infection with bacteria that possess the enzyme urease, 9% of stones are composed of uric acid, and the remaining 1% of stones are composed of cystine or other types of stones associated with the intake of certain medications. The stones ultimately form due to the supersaturation phase of these substances in a solution and their transition from liquid to solid.
A kidney stone (urolith) can be as small as a grain of sand, as large as 2.5 cm (1 inch), or more significant in diameter. Sometimes, the stone can leave the kidney and travel down the ureter to the bladder. From the bladder, the stone passes through the urethra and out of the body in the urine. This stone passage creates renal colic, which usually begins as a mild discomfort and progresses to a growing pain in the lower back within 30 to 60 minutes. If the stone’s passage is obstructed at the ureteral junction, the pain is located high in the ribs, but as the stone moves down the ureter, the pain moves down and forward. Renal colic is independent of body position and movement.
Stones smaller than 5 mm in diameter have a high probability of passing and being excreted in the urine, stones between 5 and 7 mm have a moderate probability (50%) of passing, and those larger than 7 mm almost always require urological intervention. A chemical examination of the kidney stone to determine its chemical composition is performed on stones that have passed in the urine or have been removed from the urinary tract during surgery. Patients with kidney stones are at risk of re-forming stones, so it is crucial to take preventive measures.
Chemical examination of the urolith involves evaluating the stone's size, shape, color, and weight. The formation of urinary stones can be prevented in part by changing the composition of the urine. In a simplified form, the following types of uroliths are often treated as follows:
- Hyperuricosuria and stones mainly of uric acid: urinary alkalization to increase the solubility of uric acid
- Hypercalciuria and mainly hydroxyapatite stones: uric acid to increase the solubility of calcium. However, the treatment depends on urine pH and urinary phosphate, sulfate, oxalate, and citrate concentrations. Thiazide diuretics reduce urinary calcium concentration and increase urine volume.
- Peroxaluria and calcium oxalate stones: daily increase in fluid intake and decrease in daily calcium intake
- Magnesium phosphate stones (struvite): investigation and treatment of possible urinary tract infection
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
