Understanding Kidney Stones

An Outline of Kidney Stones

Our kidneys are two bean-shaped excretory organs responsible for releasing nitrogenous waste products from our body. The fluid filtered through kidneys enters into ureters, bladder and comes out through the urethra ( the tube that opens outside). About 180 litres of blood is circulated daily through kidneys eliminating around 1.5 liters a day. Once in a while, salts and minerals present in the filtrate (fluid filtered from blood) bond together to form crystal-like stones commonly in size of a sugar crystal which usually passes even without knowing. But when larger stones become precipitated, they become troublesome, resulting in a number of symptoms. This scenario is characterized as the famed ‘kidney stones’ or nephrolithiasis.

Having gained some notoriety as one of the most painful conditions, stones are a common surgical issue as one in every 20 people usually develops stones at some point in their lives. These are more frequent in males than females and the frequent age category is 30 to 60 years of age.

Common reasons for stones

Most frequent cause of stones is the ‘dehydration’ as when you don’t drink adequate fluids your urine becomes concentrated and it contains more minerals in a small volume of water, ultimately giving rise to stones. Few other causes are listed and explained below.

  • High protein diet : Increases uric acid excretion resulting urate stones.
  • Obesity : According to studies individuals weighing more than 220 pounds are 90% at risk.
  • Gastric bypass surgery : Can result in low urine output and high oxalate excretion resulting oxalate stones.
  • Drugs : antacids, diuretics (drugs causing increased urine passage)

They come in different types

Four main types are there,

  • Calcium oxalate 70% : Most common type. Oxalates are a naturally occurring substance in a number of foods. These are small stones usually less than 7mm and chiefly caused by dehydration
  • Uric acid 10%: Caused by the prolonged acidity of urine due to ‘purine’ rich diet. Ex, fish, shellfish and meats plus dehydration.
  • Struvite 5-10%: Usually due to urinary infections and common in females compared to others. Treating the infection can alleviate the problem.
  • Cysteine <5%: Rare, occurs in the genetic disorder called ‘cystinuria’

So, to summarise, oxalates and urates are the most commonly seen in the medical field and caused by inadequate fluid intake and high protein diet.

How painful are they?

Small stones are asymptomatic and pass without causing any blockage. You get pain when a large (>5mm) stone is lodged commonly in the ureters and occasionally in the urethra. Ureteric pain is agonising and often mentioned as the ‘worst pain ever experienced’, by sufferers. Pain can be localized in back and groin often radiating from former to latter. The reason behind pain is the spasmodic contractions of ureters in order to push the stone forward. However, when the stone has passed into the bladder it won't cause any pain.

Other features include nausea and vomiting, blood in urine, frequent passing of urine and fever, if there is an association with urinary tract infection (UTI).

How to manage? Will I need surgery?

What matters is the stone size and less than 5 mm ones (98%) will be passed without causing much disturbance and may not need any kind of intervention. However, larger stones will have to be broken up using ultrasound or laser. Extremely larger stones will be directly opened and removed, called keyhole surgery. Nevertheless, pain management is also crucial and may need intravenous painkillers like NSAIDS and opioids. Antispasmodic drugs are divine as they can minimise the spasmodic ureteric pain.

Prevention is better than cure

People with a history of kidney stones are more prone to develop another one within 10 years, studies suggest. The reason behind is evident, which is improper hydration. With or without a history you should drink plenty regularly for keeping your urine diluted. Its color is a good indicator as darker urine is more concentrated. If you are living in a tropical region, you may need to double your regular intake. Other measures are lowering red meat and seafood intake, limiting calcium and sodium intake and increased citrate intake from fresh citrus fruits.

Nonetheless, it is not vice to have an unnecessary fear in kidney stones as most stones are not painful and easily passed.

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Last Reviewed:
December 20, 2016
Last Updated:
October 18, 2017