What are the parts of the urinary system?
The urinary system consists of the kidneys, ureters, urinary bladder, and urethra.
What are the functions of each part?
The function of each part is:
- The kidneys form the urine.
- The ureters carry the urine from kidneys to the urinary bladder.
- Urinary bladder is a sac like structure which temporarily stores the urine.
- Urethra is a tubular structure that carries the urine from the urinary bladder to the outside.
What are urinary stones and how they are formed?
Urinary stones are the stones occurring in the urinary tract. The stones can occur when urine becomes highly concentrated with the substances such as calcium, oxalate, and phosphorus. A stone may stay in the kidney or travel down the urinary tract. Kidney stones vary in size. A small stone may pass on its own, causing little or no pain. Whereas, a larger stone may get stuck along the urinary tract and can block the flow of urine, causing severe pain or bleeding.
What is the incidence of urinary stones?
The lifetime prevalence of kidney stone disease is estimated at 1% to 15% varying according to age, gender, race and geographic location. It is estimated that, men are three times more likely to be affected than women.
Where are stones located?
Stones can be present anywhere along the urinary tract starting from the kidneys to the bladder and urethra, but they are commonly located in the kidney and the ureter.
Which types of urinary stones are commonly seen?
The different types of urinary stones are as follows:
Calcium stones are the most common type of kidney stones. In that, calcium oxalate stones are more common and they are caused by high calcium and oxalate excretion in urine.
The other frequently seen stone type is uric acid stones. A diet rich in purines substances found in animal protein such as meats, fish, and shellfish may increase uric acid in urine which settles down and form a stone by itself or along with calcium.
Another type of stone observed only during urinary tract infection is termed as struvite stone and it is more commonly seen in women. This type of stone is caused by urea-splitting bacteria such as Proteus mirabilis. This bacteria produces urease enzyme that will breakdown urea to ammonia and promote the development of struvite stone. Staying infection free may prevent struvite stone formation.
Calcium stone Uric Acid Stone Struvite Stones
What are the causes and risk factors?
Several factors increase the risk for developing kidney stones.
- Age: The peak incidence of stone disease is in the fourth to sixth decades of life.
- Gender: More common in adult men than women.
- Geography: The prevalence of stone disease is higher in hot or dry climates such as the mountains, deserts or tropical areas.
- Climatic condition: Highest incidence is observed in summer months.
- Water: Low fluid intake is directly associated with kidney stone formation.
- Body Mass Index (BMI) and Weight: Risk of stone disease is directly related with weight and BMI.
What are the symptoms of kidney stones?
Patients with the kidney stone disease usually present with sudden onset of loin pain described as renal colic. This pain spreads to the groin and genital area. Often the pain is severe.
Other symptoms may include nausea and vomiting. Sometimes blood may appear in urine which is called as haematuria. Frequency of urination increases and also there is pain or burning sensation during urination.
How are urinary stones diagnosed?
The doctor will diagnose urinary stones by following means:
- Medical history
The doctor will ask about present symptoms, past history of kidney stones, family history of kidney stones and history of past medical conditions.
- Physical examination
The doctor will do the following examination.
o Abdominal examination
o Lightly tapping on the kidney region.
o Fever may indicate a urinary tract infection
- Laboratory tests
Urinalysis is done to detect the presence of blood (hematuria) and bacteria (bacteriuria) in the urine. Other tests include blood tests which evaluate kidney function.
- Imaging tests
Commonly done imaging test is X-ray of abdominal region. The other tests include ultrasonography and CT scan. Doctor may advice intravenous pyelography (IVP) test where in the dye is injected into the blood vessel for better vision of urinary system and it aids in the evaluation of the kidney function.
In some patients, stone is accidently detected when patients goes for checkup for some other purpose.
What are the various treatment options?
The treatment of urinary stones depends on the size, site and type of the stone. Small stones usually pass through the urinary tract without treatment. However, larger stone or the one that blocks urine flow and causes great pain may need more urgent treatment.
The treatment options are as follows:
1. Conservative therapy:
This is the treatment modality is used for stones less than 4 mm in size.
It inIt involves:
(e.g. glass of water, lemon juice, orange juice)
- Drink plenty of water (10-12 glasses/2.5 to 3 liters) per day.
- Drink even more if you live in a hot climate or do a lot of physical exercise. This will help you to balance your fluid loss.
- Drink evenly throughout the day.
- Lemon and orange juice may be helpful as it provides high amount of citric acid which is an inhibitor of stone formation.
Have a balanced and varied diet.
- Fruits & Vegetables
Eat lots of fruits and vegetables. (e.g. water melon, cauliflower)
- Make sure your diet contains a sufficient amount of calcium (about 1,000 mg a day). (e.g. milk, yoghurt, cheese)
- Eat more foods which have low oxalate content.
(e.g. eggs, lentils, peeled apples, cauliflower, squash etc.)
Foods to be Restricted:
- Reduce the amount of salt in your diet
(e.g. canned soups/vegetables, salty snacks, added salt, spices etc.)
- Restrict food containing excess of oxalate
(e.g. beetroot, sweet potatoes, nuts, dark chocolates, coca, spinach, black tea, rhubarb etc.)
- Limit intake of animal proteins
(e.g. sardines, organ meat (such as brain, liver, kidney), sweetbreads, mutton, beef, pork and red meat.)
- Maintain healthy weight
- Adopting healthy lifestyle
For larger stones usually surgery is needed. The treatment options include:
a) Extracorporeal Shock Wave Lithotripsy (ESWL)
- This technique is preferred for kidney stones smaller than 2 cm and ureteric stones larger than 10 mm in size.
- In this, shock waves are focused on stones and they are fragmented.
- The stone fragments later on are passed through urine.
b) Percutaneous Nephrolithotomy (PCNL)
- This procedure is preferred for renal stones larger than 2-3 cm in size.
- Here in, an instrument called nephroscope is passed through skin into the kidney and stone is fragmented and removed.
c) Ureteroscopy (URS)
- An instrument called ureteroscope is passed through the urethra and bladder and into the ureter.
- This technique is preferred for ureteric stones larger than 10 mm in size.
- Small stones are removed and large stones are fragmented. Fragments are then removed through scope and some smaller fragments pass via urine.
3. Medical Therapy
There are effective medicines available for expulsion of small stones in ureter and for the prevention of recurrence of stones.
The risk of recurrence of stone is very high and it was found that, 50% of the patients experience a recurrence within 10 years of initial stone episode.
Other measures which aid in preventing the recurrence of stones include increased fluid intake, dietary and life style modifications as mentioned earlier.