A pain in the side

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Daniel, of Dunedin, asked: How are kidney stones formed and what can be done about them?

Assoc Prof Kirk L. Hamilton, a physiologist from the University of Otago, responded.

What do Ava Gardner, Bing Crosby, Anna Kendrick, William Shatner, Indira Gandhi and Benjamin Franklin all have in common? These famous individuals have all experienced kidney stones!

I teach kidney physiology at the University of Otago, but I have never been asked about kidney stones! Although, as I ponder these questions, I quickly recall when my father had kidney stones back in the 1960s. I vividly remember the pain he suffered.

Nephrolithiasis, commonly known as kidney stones, occurs when small crystalline stones form inside the kidney. Generally, calcium oxalate stones, the most common type of stones, pass out of the body, undetected and painlessly with urine. Other types of kidney stones are composed of calcium phosphate, uric acid or struvite (magnesium ammonium phosphate). In some cases, substantial stones can form and cause symptoms such as intense groin pain, lower back pain, cloudy urine, and even blood in the urine. These larger kidney stones may break apart and become lodged in the ureters (paired tubes that connect the kidneys to the bladder) and prevent the flow of urine. Left unchecked, kidney stones can lead to kidney damage.

How can one prevent kidney stones? There is the old adage that drinking 2-3 litres of water a day will keep your urine dilute and reduce the risk of kidney stones. Additionally, decreasing the intake of certain oxalate-rich drinks and foods (eg caffeine, beets, nuts, chocolate, tea, salt, rhubarb, spinach, okra, and potato chips) can reduce the chance of developing kidney stones. Some of these items might be easier to give up than others for the benefit of your kidneys.

The world’s largest recorded kidney stone was reported this June. It weighed 800g, measured 13.37cm long and 10.55cm wide. It was much bigger than a 500g block of butter! So, what can be done for individuals who have large kidney stones that cannot pass out of the body? There are two options. One procedure is to perform an ESWL (extracorporeal shock wave lithotripsy) in which sound waves bombard the stone and break it into smaller pieces that then can be passed. The other procedure is percutaneous nephrolithotomy, surgical removal of the stone via a small incision in the patient’s back.

Some men claim that passing a kidney stone is more painful than a woman giving birth ... I know my wife would not agree! I leave you with a dad joke ... What did the kidney stone say to the man? Urine trouble!