Kidney stones are a chronic condition characterized by the presence of calculi or stones in the kidney or urinary tract (ureters or bladder). It can also be called urolithiasis or nephrolithiasis.
These calculi are nothing more than solid material formed inside the kidney from substances eliminated in the urine. They can remain in the kidney or move outwards through the urinary tract. In the latter case, they can obstruct urine flow, causing very intense pain or renal colic, which is the most characteristic symptom. Other symptoms that may appear as a result of kidney stones include:
- Pain in the lumbar area or lower back that radiates to the anterior abdomen and genitals
- Blood in the urine
- Fever and chills
- Vomiting
- Foul-smelling or cloudy urine
- Urinary tract infection or a burning sensation during urination
There are five types of kidney stones:
- Uric acid. Formed by an excess of protein in the urine. Their formation is clearly related to acidic urine.
- Calcium phosphate. Primarily formed by a high concentration of calcium in the urine, which has not been absorbed into the bones and has ended up filtering into the kidneys. Their formation is related to alkaline urine.
- Calcium oxalate. Also composed of calcium, their appearance depends on a previous crystalline formation (commonly uric acid or calcium phosphate). This is the most common type of stone.
- Struvite. Formed by phosphate, calcium, and magnesium. They are directly related to the presence of bacteria (urinary infection) and alkaline urine.
- Cystine. Formed by an excess of cystine in the urine. This is the least common type of kidney stone but has a higher recurrence rate in affected individuals. Prevention is complex; among other measures, strict control of urinary pH is recommended to maintain it at alkaline levels above a pH of 7.5.
The size of the stones can vary, being as small as a grain of sand or as large as a pearl. Their shape can also differ, being smooth, rounded, or pointed. They are generally brown or yellowish.
Diagnosis can be made through a urinalysis, to detect the presence of stones in the blood, or by an abdominal X-ray, intravenous urography, or abdominal ultrasound, to detect their presence in the kidney or urinary tract.
Most kidney stones are eliminated from the body without the need for medical treatment. However, if they are too large, they cannot be expelled naturally and will require specialized treatment for removal. Currently, there are different methods for stone extraction:
- Shockwaves. Waves produced by a machine that are directed directly at the kidney stone with the aim of breaking it into smaller pieces so they can be eliminated through urine. This is known as extracorporeal shock wave lithotripsy, as lithotripsy means "to break stones" in Greek.
- Surgery. An intervention through a small incision in the back, creating a narrow tunnel through the skin and kidney to reach the stone with the aim of locating and extracting it. This is known as percutaneous nephrolithotomy.
- Ureteroscopy. Extraction through the ducts themselves with a ureteroscope, an instrument with an incorporated camera, with the aim of locating and extracting the stone.
Prevention is the best way to avoid the formation of calculi or stones in the kidney. To do this, some daily habits can be taken into account that will help with this purpose:
- Drink more water, at least 2.5 liters a day, to more easily eliminate substances that can accumulate in the kidneys
- Drink more fluids, such as juices, soups, infusions, etc., and limit coffee
- Follow a low-calorie diet, with little salt, limiting animal proteins, sugars, and alcohol
- Reduce meat intake if the stones are uric acid
