What causes kidney stones?

Isaac Yeboah Health Jul - 06 - 2013 , 16:16

Dear Miirror Doctor,

I recently experienced a very sharp pain which tore through my flanks into my scrotum. That was the most excruciating pain I have ever experienced. I consulted a doctor who diagnosed kidney stones. Please, what causes these stones and how can I prevent them from recurring?

Worried man, Darkuman.

Dear Worried man, the kidney acts as a filter for blood, removing waste products from the body and making urine. It also helps regulate electrolyte levels that are important for body functioning.

In some people, chemicals crystalise in the urine and form the beginning, or nidus of a kidney stone. The size of the stone doesn't matter as much as where it is located and whether it obstructs or prevents urine from draining.

When the stone sits in the kidney, it rarely causes problems, but when it falls into the ureter (the tube connecting the kidney to the bladder), it acts like a dam.

As urine production continues, pressure builds up behind the stone and causes the kidney to swell. This pressure is what causes the pain of a kidney stone, but it also helps push the stone along the course of the ureter.

When the stone enters the bladder, the obstruction in the ureter is relieved and the symptoms of kidney stone are resolved.

There is no consensus as to why kidney stones form. Some people are more susceptible to form kidney stones and also heredity may play a role, especially in people with high levels of calcium in their blood.

Where a person lives may predispose them to form kidney stones. There are regional "stone belts," with people living in this zone having an increased risk of stone formation.

The hot climate in this region combined with poor fluid intake may cause people to be relatively dehydrated, with their urine becoming more concentrated and allowing the chemicals to come into contact to form a stone.

Diet may or may not be an issue. If a person is susceptible to kidney stones, then foods high in calcium may increase the risk.

People taking diuretics (or "water pills") and those who consume excess calcium-containing antacids can increase the amount of calcium in their urine and potentially increase their risk of forming stones.

Excess amounts of vitamins A and D are also associated with higher levels of calcium in the urine.

When a tubular structure is blocked in the body, waves of pain occur as the body tries to unblock the obstruction. These waves of pain are called colic. Kidney colic classically presents as an intense and sudden pain, usually located in the flanks and radiate to the groin with no relieving factors.

It may wax and wane, but there is usually a significant underlying ache between the acute spasms of pain. Sweating, nausea and vomiting are common. Blood may be visible in the urine because the stone has irritated the kidney or ureter.

By way of laboratory investigations, urine analysis ultrasound and computerised tomography scans may demonstrate the exact location of the stone. Plain x-rays are used to track the course of the stone.

Prevention is always the preferable way to treat kidney stones. Remaining well hydrated keeps the urine dilute and helps prevent kidney stones from forming.

Most kidney stones, given time, will pass the stone on their own, and treatment is directed towards symptom control. In emergency situations, intravenous fluids and powerful pain killers may be provided.

If the pain is intractable or if vomiting persists, then admission to the hospital is necessary. Also, if an infection is associated with the stone, then admission to the hospital is warranted.

Because of their size or location, some stones may not be able to be passed without help. If the stone is high near the kidney, and is large, then it needs to be broken into smaller pieces to allow those small pieces to pass more easily into the bladder. This is done by means of shock waves which vibrate the urine surrounding the stone and causing the stone to break up.

If the stone is located in a place where the shock wave cannot work or if there is a need to relieve the obstruction urgently, ureteroscopy, a procedure in which instruments are threaded into the ureter to allow placement of a stent (a thin hollow tube) to by-pass the obstruction is done. These procedures are done by the urologist.

Since most patients have two kidneys, a temporary obstruction of one is not of great significance. For those patients with only one kidney, an obstructing stone can be a true emergency, and the need to relieve the obstruction becomes greater. A kidney that remains completely obstructed for a prolonged period of time may stop working.

While kidney stones and renal colic probably cannot be prevented, the risk of forming a stone can be minimised by avoiding dehydration.

Keeping the urine dilute will not allow the chemical crystals to come out of solution and form the nidus of a stone. Making certain that the urine remains clear and not concentrated help minimise stone formation.

Medication may be prescribed for certain types of stones, and compliance with taking the medication is a must to reduce the risk of future episodes.