What Causes Kidney Stones?

What Causes Kidney Stones?

The largest kidney stone ever recorded weighed over a kilogram and measured 17 centimeters in diameter. It's essential to clarify that this massive stone was not ingested like a coconut; rather, kidney stones form within the body and can be excruciatingly painful to pass. A kidney stone is a solid mass of crystals that can develop in the kidneys, ureters, bladder, or urethra. The urine contains various compounds, such as calcium, sodium, potassium, oxalate, uric acid, and phosphate. When the levels of these substances become too high, or if the urine becomes overly acidic or basic, the particles can clump together and crystallize. Over time, these crystals grow, eventually forming a detectable stone over weeks, months, or even years. The most common type of kidney stone, accounting for about 80% of cases, is made of calcium oxalate. However, less common stones can be composed of calcium phosphate or uric acid. Additionally, a different type of stone known as struvite, made of the minerals magnesium ammonium phosphate, can result from a bacterial infection. In rarer instances, kidney stones can be linked to genetic disorders or certain medications.

Kidney stones may go unnoticed until they start to move. When a stone travels through the kidney and into the ureter, its sharp edges can scratch the walls of the urinary tract, causing intense pain. The nerve endings in this tissue transmit agonizing pain signals through the nervous system, and the scratches can lead to blood in the urine. This pain is often accompanied by symptoms like nausea, vomiting, and a burning sensation while urinating. In more severe cases, a stone may grow large enough to block the flow of urine, potentially causing infections, backflow, and kidney damage. However, most kidney stones do not reach this severity and may not require invasive treatment. Stones smaller than five millimeters in diameter typically pass out of the body naturally. Doctors often recommend drinking large amounts of water to facilitate this process and may suggest painkillers if needed. For slightly larger stones, medications like alpha blockers can help relax the muscles in the ureter, making it easier for the stone to pass. Another medication called potassium citrate can aid in dissolving the stones by creating a less acidic urine. For medium-sized stones up to approximately ten millimeters, a treatment option is extracorporeal shock wave lithotripsy, which uses high-intensity pulses of focused ultrasonic energy to crush the stone into smaller pieces that can be expelled from the body more easily. However, when the stone is too large for this approach, more invasive treatments may become necessary. Techniques such as placing a stent in the ureter to widen it, using optical fibers to deliver laser pulses to break up the stone, or surgical removal through an incision in the back or groin may be employed.

There are four primary types of kidney stones:

Calcium Stones: The majority of kidney stones fall into two categories - calcium oxalate and calcium phosphate stones. Oxalate stones are the most common and result from an accumulation of calcium oxalate in the urine. On the other hand, phosphate stones are less common and can be caused by autoimmune diseases and certain medications.

Uric Acid Stones: Uric acid stones form in acidic urine. They arise as a byproduct of the breakdown of animal proteins, leading to increased acidity in the urine. Conditions like gout, chemotherapy, and other disorders can heighten the risk of developing this type of stone.

Struvite Stones: These stones consist of magnesium ammonium phosphate and/or calcium carbonate and are commonly known as infection stones. They are a consequence of chronic and recurring urinary tract infections caused by specific types of bacteria.

Staghorn Stones: Staghorn stones are characterized by their large and branched appearance, occupying a significant portion of the urinary system. They can be a mixture of struvite stones and calcium carbonate stones and typically contain bacteria. If left untreated, they can damage the kidney or even lead to life-threatening blood infections or sepsis.

Additionally, there is another type of kidney stone called Cysteine Stones, which results from an inherited condition known as cystinuria.

To prevent kidney stones, individuals at risk may be advised by their doctors to drink plenty of water, which helps dilute the compounds, like calcium oxalate, that can eventually lead to painful stones. Certain foods, such as potato chips, spinach, rhubarb, and beets, which are high in oxalate, might be limited to reduce the risk. Surprisingly, while calcium is often associated with kidney stones, calcium in foods and beverages can help by binding to oxalate in the digestive tract before it reaches the kidneys, preventing stone formation.

It's worth noting that kidney stones are becoming more prevalent, but it's unlikely that the record for the largest stone will be broken anytime soon.