Kidney stone analysis

Your doctor may order this test if you show the following symptoms of kidney stones:

• Pain when urinating
• Sharp pain in the abdomen, sides or groin
• Back pain
• Nausea and vomiting
• Blood in urine
• Bad-smelling or cloudy urine
• Frequent urge to urinate

This test is mainly done to determine the chemical makeup of a stone and to get information on how to prevent the formation of more stones in the future. If the stone has already passed out through urine and you have kept it, your doctor may ask you to bring it for analysis. He/she will guide you on how to clean and pack the stone.

For larger stones, which cannot be passed through urine, you may require a minor surgical procedure to remove the stone.

If you have symptoms of a kidney stone, your doctor will give you a strainer made of fine mesh or gauze to filter your urine and collect the stone (just in case you pass one or small particles from one). Following are the steps to collect the stone for testing:

• Filter your urine through the strainer each time you urinate.
• Check the strainer carefully for small particles.
• If you see a stone, keep it in a clean container and leave it to dry.
• Do not contaminate the stone by adding urine or any fluid into the container.
• Do not cover the stone with tissue or tape, as it can change the test results.
• Take it to your doctor for analysis.

In case the stone is too large to pass, be prepared for a surgical procedure. 

Both physical and chemical methods are used for a kidney stone analysis. Physical analytic methods are widely used in laboratories because they can identify a diversity of components. Chemical methods are not commonly used, as they fail to analyse stones accurately. The following methods are used for the study of kidney stones:

• X-ray diffraction and Fourier transform infrared spectroscopy: These are widely used methods that not only help in determining each component of a stone but also provide concentrations of every component. These methods detect both calcium oxalate and calcium phosphate stones and non-calcium stones, such as protein, uric acid, cystine, lipid and struvite stones.
• Energy Dispersive X-Ray Analysis: It gives an accurate composition of different elements in a stone. This method also helps in identifying the initiation and the formation of stone.
• Thermogravimetric analysis: This is a simple and quick method that uses increasing temperature to determine the mass of any thing.
• Wet chemical analysis: This method only works well if the stone is made of a single type of mineral stone and does not give good results for mixed stone.
• Scanning electron microscopy: This method is used to study the texture and morphology of stones that are 1-5 nanometres in size.
• Powder X-ray diffraction: Powder X-ray diffraction can identify the constituents of a stone. It can simultaneously distinguish and measure all the crystals in a stone.

The results of a kidney stone analysis show what type of kidney stone you had. Based on the chemical makeup of the stone, your doctor will recommend medicines and measures to prevent the formation of more stones.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.