Kidney stones (also known as nephrolithiasis) are small hard deposits that form in the kidneys and are usually painful when passed. If the stones cause severe pain, the condition is called renal colic.
Small stones may be passed out without any symptoms but sometimes the stones may block the ureter (connecting the kidney to the bladder) or the urethra and cause severe pain or an infection.
Kidney stones are formed when an imbalance occurs in various chemicals that are present in the urine. The most commonly involved chemicals are calcium, oxalate, citric acid, uric acid, and cysteine. When there is an abnormal composition of urine such as with certain medical conditions, some of these chemicals can precipitate and form crystals, that later result in the formation of stones. In addition, certain medications can also contribute to the formation of kidney stones.
You are at increased risk of developing recurrent kidney stones if:
- You don’t drink enough of water.
- You eat a high protein, low fiber diet high in sodium and sugar. Too much sodium in your diet means that the amount of calcium your kidneys has to filter increases your risk of kidney stones.
- You have had recurrent kidney or urinary infections
- Only one of your kidney works
- You are inactive or bed bound.
- Family or personal history of kidney stones increases your risk of developing stones.
- If you already had one or more kidney stones, you’re at increased risk of developing another.
- Being obese.High body mass index (BMI) and weight gain have been linked to an increased risk of kidney stones.
- Medical conditions.Diseases and conditions that may increase your risk of kidney stones include renal tubular acidosis, cystinuria and hyperparathyroidism.
Calcium stones are the most common stones and occur in about 80 percent of patients with kidney stone disease. Among calcium stones, the most common form of stones found is calcium oxalate stones followed by calcium phosphate stones. Other important stones are those composed of other chemicals like uric acid, struvite (magnesium ammonium phosphate) and cystine stones.
High calcium levels in urine and high oxalate levels in the urine can cause a formation of calcium stones. Patients who do not drink enough water are also at risk of developing calcium stones.
Recurrent urinary tract infections with certain bacteria, for example, Proteus or Klebsiella, create an environment in the upper urinary tract that is favorable for the formation of a fast-growing stone composed of magnesium ammonium phosphate.
Some patients have a genetic abnormality that causes them to excrete excessive cysteine in the urine leading to the formation of cystine stones.
Pain due to kidney stones can vary in intensity and is usually present in the flank or lower abdomen. The pain may be associated with nausea and vomiting and may be more intense when passing urine.
Another common presentation of kidney stones is the appearance of blood in the urine. Other symptoms include frequent and painful urination and fever.
If there is blockage of urine flow, it may result in infections which can damage your kidneys. There is a 20% chance of recurrence in 5 years.
Some general precautions for a patient diagnosed with kidney stone disease are:
- Increase your daily fluid intake (water intake should exceed two litres per day)-if you already have renal failure you need to check with your doctor about how much water you can have.
- Lower the content of animal protein in your diet (reduce meat intake)
- Lower daily salt intake (2000 mg sodium restriction per day)
- Lower intake of high oxalate content foods (example: spinach, beets and chocolate)
- Limit coffee, tea and cola intake
- Do not take excess of Vitamin D supplements. Take them only as prescribed.
- Reduce your daily sugar intake
- Lemon and cranberry juice are considered safe
Most kidney stones will be small enough (< 4 mm in diameter) to be passed out in your urine. These also cause pain that lasts a couple of days and disappears when the stone has passed out.
Medication: If you have severe pain, you will be given a painkiller as well as medication for nausea and vomiting.
You should drink enough water to make your urine colorless to help the stone to pass out.
Admission to hospital: You may be admitted to hospital if you have severe pain and if you are at increased risk for any reason such as if you have only one kidney, you are vomiting too much and cannot keep any fluids down or if you have other medical problems or are advanced in age.
Stones that do not pass on their own are treated by a procedure.
ESWL (Extracorporeal Shockwave Lithotripsy): uses X-rays (high-energy radiation) or ultrasound (high-frequency sound waves) to locate the kidney stone. A machine then sends shock waves of energy to the stone through the skin to break it into smaller pieces so it can be passed in your urine. This non-invasive procedure is safe and easy to practice and has quickly gained popularity instead of surgery. The procedure is performed under sedation as it can be uncomfortable. After the lithotripsy, all the tiny particles of the stones get removed by the kidney through the urine.
However, before undergoing the procedure, you should consult your doctor about your current physical condition and any medication or supplements you may be taking.
Endoscopy: For those stones that cannot be removed with ESWL, there are procedures that are performed through endoscopy (passing a lighted tube to visualize and perform surgery through natural body passages). These are fairly simple procedures and patients can often go home the same day.
Laser treatment uses a machine called the Holmium Laser to break down the stone and is used in combination with endoscopy.
Ureterorenoscopy: This surgery involves passing a long, thin telescope called a ureteroscope through your urethra (the tube through which urine passes through out of the body) and into your bladder. It is then passed up into your ureter up to where the stone is lodged. Ureterorenoscopy is also sometimes known as retrograde intrarenal surgery (RIRS).
The surgeon may either try to remove the stone using another instrument or laser energy may be used to break the stone up into small pieces so that it can be passed naturally out in your urine. Your surgeon may place a plastic tube called a stent inside you temporarily, to allow the stone fragments to drain into the bladder.
Ureterorenoscopy is performed under general anesthesia.
Percutaneous Nephrolithotomy (PCNL): Percutaneous Nephrolithotomy or PCNL, is a procedure to remove medium-sized or larger kidney stones from the patient’s urinary tract by means of a nephroscope that is passed into the kidney through a track created in the patient’s back. The term “percutaneous” means that the procedure is done through the skin. Nephrolithotomy is a term formed from two Greek words that mean “kidney” and “removing stones by cutting.”
The nephroscope is an instrument with a fiber optic light source and two additional channels for viewing the inside of the kidney and washing out the area. The surgeon may use a device with a basket on the end to grasp and remove smaller kidney stones directly. Larger stones are broken up with an ultrasonic or electrohydraulic probe, or a holmium laser lithotriptor. The holmium laser can be used on all types of stones.
Postoperatively, you will have a urinary catheter to drain the urine through the bladder and a nephrostomy tube is placed in the incision in the back to carry fluid from the kidney into a drainage bag.
After surgery, you may experience some discomfort due to the presence of the drainage tube. You will have an x-ray to evaluate the position of the stent and catheter. Your doctor will observe your progress and decide on how long the stent should remain. The catheter is generally removed after 24 hours. The nephrostomy tube is usually removed while you are still in hospital but may sometimes be left in after you are discharged.
Preparing yourself in advance can reduce your anxiety before undergoing surgery.
You should inform your doctor if you are taking any medication and follow instructions about discontinuing them.
You should stop taking drugs such as aspirin, ibuprofen, and naproxen 2weeks prior to surgery. Many of these medications may contribute to unwanted bleeding during the surgery.
If you have symptoms such as burning sensation, blood in the urine, urinary frequency and urgency or fever 2 weeks prior to the surgery, inform your doctor.
You may be asked to take a laxative a day before surgery to prevent the risk of constipation during the recovery period.
You should take nothing by mouth for at least 8 hours before (from midnight the night before) surgery and have only a light dinner.
You should contact your doctor if you have a fever of 38°C (100.4°F) or higher with shivering or chills and if the pain gets worse, particularly if it is a sudden, severe pain.
Complications of treatment of kidney stone are:
- Blockage of the ureter by the fragments of stone
- Injury to the ureter or bladder