Kidney stones are lumps of crystalline minerals and salts that form inside one or both kidneys. The condition, which is also called renal calculi or nephrolithiasis, is caused when urine gets concentrated, allowing the minerals and salts to crystallize, stick together and form noticeable hard lumps over time.
Kidney stones can affect any part of the urinary tract, from the kidneys to the bladder. Usually, smaller stones get cleared out from the body while urinating, but some larger stones can get stuck in the urinary tract causing severe pain and, if left untreated, also infections due to the backflow of urine.
A kidney stone can be as little as a grain of sand and as big as a pebble. In rare cases they have been known to get as large as a golf ball, but the larger the size the more noticeable are the symptoms.
The symptoms, however, do not show up until the stones move inside the kidney or from the kidney to the ureter, a tube that connects the kidneys to the bladder.
When a stone gets stuck in the ureter (urolithiasis), it obstructs the urine flow from the kidneys and makes the ureter to contract and swell, causing severe pain. Some common symptoms experienced during this phase are:
- Severe pain in the lower back and lower abdomen that comes in waves and lasts for long
- Urine discoloration due to pinkish, red or brown blood (hematuria)
- Frequent urge to urinate
- Pain while urinating
- Inability to urinate or dripping urination
- Cloudy or foul-smelling urine
- Nausea and vomiting
- Fever with or without chills
Experiencing these symptoms indicates a severe kidney condition and you should consult with a doctor at the earliest.
Water dilutes minerals and salts present in the urine and clears them out during urination. When the body is deprived of fluid, the urine becomes more concentrated leading to the crystallization of minerals and salts in it. Moreover, the levels of chemicals that prevent crystallization also dip when there is insufficient fluid intake. These crystals start sticking together and form a hard lump over time, causing kidney stones.
There are several factors that can increase the risk of kidney stones. These include:
- Drinking too little water
- Too little or too much exercise
- High protein diet
- Weight loss
- Diet having excessive sugar (especially fructose) or salt
- Any ongoing urinary tract infection or a family history of kidney stones
- Overuse of medications such as calcium-based antacids, aspirin, vitamin C
A kidney stone varies in shape, size and colour. This variation depends on the type of stone from which mineral or salt they are formed. The main types are:
- Calcium stones — the most common
- Struvite stones — usually caused by any urinary infection
- Uric acid stones — caused by a high amount of uric acid in the urine
Analyzing and establishing the type, severity and location of stone can be done by a physical examination to identify the location of the pain. Laboratory tests include a urine test to check for any infection or stones passed during urination, and a blood test to check kidney function and analyze the levels of stone-causing substances like calcium, uric acid or phosphates.
Imaging techniques such as X-ray, ultrasound and CT scan are used to assess the location and size of the stone.
Most small stones can clear out during urination and require no treatment apart from drinking a lot of water until they clear out. In cases where this isn’t happening or there is pain, a doctor can prescribe a pain reliever or alpha blockers that will dilate the ureter muscle to help pass urine with lesser pain. There are also medications that lower the level of stone-causing substances.
But in cases where the stone is large and cannot be cleared out, it can be surgically removed or broken down into small fragments to let it pass through urine. Some of the surgical methods are:
- Shock wave lithotripsy (SWL) uses sound waves to create a strong vibration that breaks down the stone into tiny fragments, allowing it to get cleared out naturally. This method causes a moderate amount of pain and might require the use of anaesthesia or pain reliever before performing
- Ureteroscopy uses a long telescopic instrument (ureteroscope) that is inserted into the tube from which urine passes to the bladder and then to the ureter. Any stone lodged in the ureter is then either removed or broken down into tiny fragments
- Percutaneous nephrolithotomy (PCNL) is done in rare cases where the stones are very large. A small incision is made at the back and a nephroscope instrument is inserted into the kidneys to completely remove or break down the kidney stone into tiny fragments.