The following are the frequently asked questions answered by
Dr. C. Chinnaswami, M.S., M.Ch, F.R.C.S., Chairman,
TNURC, Kidney Stone Clinic, Chennai.

1. Has the incidence of urinary stones increased ?

It is true, incidence of stones in the kidney and ureter has increased in recent times, whereas the bladder stones that were common in children are not to be seen now a day.
Possible causes for the increase could be due to changes in life style, contributed by
· Increase in salt intake
· Increased intake of animal proteins.
· Low intake of fibers and alkalis
· Inadequate water intake.
· Use of food preservatives.

2. What chemical abnormalities are known to cause kidney stones?

The chemical abnormalities relate to the type of stones that form in the kidneys. These four types of stones and the chemical abnormalities that cause them are:

Calcium Stones: people who form this type of stone either have too much of one type of three chemicals in their urine, or not enough of another. In particular, they have either too much calcium, oxalate, or urate in their urine, or too little citrate. Eating too much salt may cause too much calcium to stay in the urine A few patients will have kidney stones from overproduction of the calcium controlling hormone, parathormone. Drinking milk does not cause kidney stones.

Struvite Stones: Chronic infection of the urine generally causes these stones. The bacteria responsible for the infection cause a chemical alteration of urine, which leads to this type of stone.

Cystine Stones: These stones form because of an inborn error of metabolism of Alanine. Abnormal amount of cystine accumulates in the body which leads to stone formation. Usually, other family members have the same condition.

Knowing the type of kidney stone is important to prescribing treatment to prevent further stone formation.

3. Where do urinary stones formed and where are they found?

It is commonly seen in the kidney and ureters. Bladder stones are common in children and in elderly persons. Most of the stones are formed in the minute tubules of the kidney and pass down. It may stay in the kidney and grow bigger or it may stay in the ureter. Majority of the stones can easily slip down to the bladder and pass out in natural way. It may get lodged at various levels and grow larger.

4. How do the stones form in urinary tract ?

Kidney excretes out large quantity of minerals and end products of metabolism and maintains the internal equilibrium of the body. The minerals are in a super saturated but soluble forms. When the balance is upset either by increase in concentration of the salts (as seen in dehydration due to sweating or diarrhea or poor intake of fluids) or turbulence of urinary stream or presence of materials like bacteria, dead papillae (tissue in kidney) tumor or foreign bodies on which the salts gets deposited and stone starts to grow.

Urinary stone has been compared to ferroconcrete in structure. It is not formed of pure crystals as in blue metal. There is a scaffolding formed by colloids, dead bacteria, tumor tissue or foreign body (like steel rods in concrete) and salts in the urine oxalate, uric acid, triple phosphate or cystine crystalline materials fill in the space between the scaffolds.

Some crystals grow well in alkaline urine whereas some stones grow only in acidic urine. Many stones grow rapidly in stagnant urine, which gets collected above obstructed urinary tract.

5. What are the symptoms of urinary stones ?

A) Pain is the commonest presenting symptoms. It may be severe, shooting from the back towards     the thigh or genitalia. This happens when the stone moves from the kidney to the ureter. It is     called renal colic or ureteric colic.

    Stones, which are inside the kidney, may not cause severe pain but dull aching pain may be felt     in the kidney area. It is a perplexing but surprising fact that big stones may remain and grow     silently whereas small stones can cause severe pain when they move about.

B) Haematuria – passing blood in the urine is another common feature of urinary stones. This blood     in the urine could be quite obvious to the naked eye or only a microscope could detect it. Severity     or quantum blood is not dependent on the size of the stone.

C) Fever may be associated with pain in stone disease. It points to the presence of infection.

D) Tenderness – this term is used to denote presence of pain on touching (palpating) various areas      of  the abdomen. This is to be distinguished from pain mentioned earlier. Presence of tenderness      denotes infection.

    When the last two symptoms fever and tenderness are noted the stone problem should be     considered serious and treated promptly.

E) Swelling – it is unusual to see any significant swelling in simple stone disease. It may be seen in     stones of long duration.

F) Nausea or Vomiting – may be associated with severe pain. It may also be a sign of kidney failure     associated with some kidney stones.