A Simple Guide to Urinary Stones

A Simple Guide to Urinary Stones
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What are Urinary Stones?
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Urinary Stones are small, solid stones which occur when salts or minerals in the urine become solid crystals inside the kidney.

How are Urinary Stones formed?
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Urinary Stones are formed usually because of the accumulation of salts and minerals especially calcium in the urine.

Usually the stones may be so small that they pass out through the urine without the knowledge of the patient.

Some however become bigger due to accumulation of the salts and minerals and the concentration of the urine.

The bigger stones may remain in the tubes of the kidney and are called renal stones.

Some smaller stones may move out of the kidney and passes through the ureters which are the the tubes bringing urine from the kidney to your bladder.
These are called ureteric stones.

If a ureteric stone gets stuck in the ureter, this can cause blockage of the urine and severe pain.(ureteric colic)

What are the types of Urinary Stones?
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Different kinds of Urinary stones form from different salts in the urine.

1.Calcium stones forms about 80% of the urinary stones.
50% are made up of calcium oxalate and the rest are calcium phosphate.
They are spiky or large and smooth


2.Uric acid stones are caused by accumulation of excess amounts of uric acid which can be due to eating a lot of meat.
They are smooth, brown and soft

3.Struvite stones (infection stones) are produced when there is too much ammonia in the urine occuring especially in urinary tract infection.
The bacteria that cause these urinary infections can generate ammonia.
They are usually large and have a horn-like shape
This kind of kidney stone is most often found in women.

4.Cystine stones occurs when there is high levels of cystine in the urine. A hereditary disorder called cystinuria is the source of high cystine in the urine.
They are yellow and crystalline

Who is at risk of Urinary stones formation?
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Risk factors include:

1.Men get urinary stone more commonly than women

2.a previous history of kidney stone - 50% will develop another one within five years.

3.a family history of kidney stones

4.Age between 20 and 40

5.Not drinking enough water

6.eating a diet high in protein

7.taking certain medicines such as diuretics (water tablets), antacids and thyroid medications

8.having only one kidney, or an abnormally shaped kidney

What causes Urinary Stones?
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Urinary Stones are caused by 4 main factors:

1.Insuffient water in the urine leading to concentration and stagnation of urine flow:
a.insufficient intake of water
b.intake of alcohol causing concentration of the blood volume

2.Excess Urinary Constituents:
a. Calcium:
High calcium intake (includes calcium tablets and high calcium milk)

Primary Hyperparathyroidism leading to high blood calcium

high Vitamin D intake cause high adsorption of calcium

medical conditions such as cancer, some kidney diseases, or sarcoidosis are more likely to develop calcium stones.


b. Oxalates:
high oxalate intake (cabbage,spinach,tomatoes, chocolates) in diet leads to high concentration of oxalates in urine

c. Uric Acid:
Gout or High Uric Acid can form crystals which may lead to stones

Treatments such as chemotherapy can also increase the risk of getting uric acid stones.

d: Cystine:
Hereditary cystinuria leads to high cystine in the urine and formation of cystine stones

About one in a hundred urinary stones is due to this illness.

Cystine stones tend to appear earlier in life between the ages of 10 and 30 years.

3. Infection of urine:
clumps of bacteria can form the nucleus of the stone.

Bacteria also produce ammonia which can promote formation of stones

4. Congenital deformity of the kidney and urinary tract:

these block the passage of concentrated urine and causes formation of stones.

What are the symptoms of Urinary Stones?
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Many Urinary stones do not cause any symptoms.
Once an urinary stone enters the ureter and blocks the passage of urine flow, it may cause the following symptoms:

1.severe pain or aching in the back on one or both sides

2.sudden spasms of excruciating pain which usually starts in the upper back below the ribs, radiates around the flanks of the abdomen, down to the pubes, groin and genitalia.

3.Urine is bloody, cloudy or smelly

4.frequent urge to urinate, or a burning sensation during urination

5.fever and chills

6.nausea and vomiting

Urinary stones can be passed out of the body within 48 hours.

Sometimes attacks of pain from urinary stones may last for over 30 days.

How are Urinary Stones diagnosed?
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1.History of ureteric colic symptoms and physical examination showing tenderness of abdomen and flanks

Other tests may be done to confirm the diagnosis and to reveal the size, location and type of stone:

2.blood tests - to identify excess amounts of certain chemicals (calcium, uric acid, oxalates, cystines) related to the formation of stones

3.urine analysis - to look for signs of infection and presence of crystals

4.X-ray of abdomen - stones that contain calcium (80%) usually appears white on X-rays

5.Intravenous urogram (IVU) - an injection of a special dye that shows up the whole urinary system on X-ray images, revealing stones that can't usually be seen

6.ultrasound scan - can detect stones in kidneys and solid internal organs

7.non-contrast helical computerised tomography - X-ray images taken at different angles - can diagnose kidney stones, and is probable the most accurate diagnostic test

How are Urinary Stones treated?
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Treatment depends on the
1.type and
2.cause of the stone.

Most stones can be treated without surgery:
1.Drinking lots of water (two and a half to three litres per day)

2.staying physically active are often enough to move stones smaller than about 5mm out of the urinary tract.

3.paracetamol or codeine may be given to reduce the pain.

4.Infections can be treated with antibiotics.

Stones that are stuck can be removed in several ways:

1.Extracorporeal shock wave lithotripsy (ESWL)
Location of the urinary stone is dtermined using X-ray imaging or ultrasound scanning.
The patient lies in a side position while a machine called a lithotriptor sends targeted shock waves to break up the kidney stone.
There may be some pain as the stone breaks up, so the procedure is usually performed under local anaesthesia.

2.Ureteroscopic stone removal
A narrow, flexible instrument called a cystoscope can be passed up through the urethra and bladder and up the ureter where the stone is stuck. The stone is captured and removed.It can also be broken up with a laser beam or shock waves generated by a device attached at the end of the cytoscope. This procedure is usually done under general anaesthesia.

3.Percutaneous nephrolithotomy (PCNL)
Large stones can be surgically removed from the kidney.
The surgeon makes a small opening at the back and uses a telescopic instrument called a nephroscope to pull the stone out or break it up with shock waves or a laser.
This procedure is performed under general anesthesia.

How to prevent Urinary Stones?
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1.drink more fluid at least three litres every 24 hours.

2.reducing the amount of calcium in the diet to a normal level(not excessively high)

3.For calcium oxalate stones, reduce intake of high levels of oxalate - chocolate, tea, cooked spinach and asparagus.

4.For uric acid stones, less meat, fish, poultry, organs, peanuts and soya beans should be taken. Daily intake of allopurinol medicine can help reduce the level of uric acid in the urine.

5.For cystine stones, medicines can be given to reduce formation of the stones.

6.For struvite or "infection" stones,long term antibiotics may prevent chronic urinary infection.


Added 4th October 2008
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Urinary stone:
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Melamine a chemical used for hardening plastic has found illegally in milk products in China in September 2008.

This causes urinary stones in babies.