What do you know about kidney stones?

24-year-old John (not real name) developed severe pain on the left side of his back. The pain was excruciating, so his family had to rush him to the hospital. Examinations revealed that he had stones in the left kidney.

Kidney stones are hard deposits of minerals and salts that form inside the kidney. They can form in the ureter (tube connecting kidney to the bladder) or in the urinary bladder as well.  One to 15 per cent people globally suffer from kidney stones. It can occur in either gender, but is more common in men.

Majority of kidney stones are formed from calcium salts, particularly calcium oxalate. Few stones are made from struvite, phosphate or cystine.

There are multiple risk factors for forming kidney stones. High protein diet as present in meat products, soya products, nuts, increase risk of stone formation.  Apple juice and grape fruit juice, beverages like cola,   also carry higher risk of stones in kidney. High intake of calcium, Vitamin D3, is also said to increase risk of kidney stone formation. This happens as in post-menopausal women taking calcium supplements for a long time.  Increased intake of salt in the diet, refined sugar, are other risk factors for forming stones in the kidney.  Dehydration as due to reduced intake of water, diarrhoea and or vomiting, enhances risk of kidney stones.

Kidney stones can occur as side effects of certain drugs like diuretics (drugs which increase urine formation), sulpha drugs, ephedrine, and etcetera. It can be one of the manifestations of certain metabolic disorders like gout, hyperparathyroidism.  Diseases of the kidney like renal tubular acidosis and medullary sponge kidney are often associated with kidney stones.

Small kidney stones less than five millimetres may cause no symptoms and may pass unnoticed in the urine. However, stones bigger than five millimetres, or multiple stones, may cause pain, which depends on the site of the stone. Pain can occur below the rib cage on the affected side, in the side of upper abdomen, in the loins or middle of lower abdomen. 

Severity and periodicity of pain depends on size of stones and recurrence.

Apart from pain, one can have fever with chills, frequency and urgency of urination, difficulty in passing urine, nausea with or without vomiting, and etcetera, one or more of these symptoms, due to kidney stones.

Presence of stones in the kidney increases risk of urinary tract infection. Recurrent stones or big size stones can damage kidney tissue leading to reduced kidney functioning and renal failure over time.  Kidney failure can also occur due to chronic obstruction to flow of urine.  Kidney damage leads to hypertension.

Kidney stones are suspected based on the clinical features. Diagnosis is confirmed by imaging techniques like renal ultrasound, computerised tomography (C.T.) scan.  Intravenous pyelography is used, where C.T. scan is unavailable. Here, a contrast is injected in the veins, followed by X-rays of the kidney. The contrast helps in visualisation of kidney stones if present. People with recurrent stones with no clear explanation are screened for any underlying metabolic disorder that increases risk of stone formation.

Prevention consists of drinking adequate amount of water. This prevents stone formation. Any small stones formed are washed away from the body due to increased urine formation.  Drinks that enhance risk of stone formation should be avoided. Alcohol should be avoided, particularly binge drinking, as it can cause dehydration due to vomiting and excess urine formation, which is a risk factor for kidney stones. White salt and refined sugar are also best voided.  Meat products and other high protein products should be taken in moderation. Dairy products reduce risk of kidney stone formation, as shown by studies.

There is no root cure for kidney stones. Pain killers are used for pain relief in case of severe pain.  Mild diuretics taken for a short while help in removal of small stones by increasing urine production. Antibiotics are used if there is associated infection.

If the pain is recurrent and severe or there are multiple recurrent stones, a large stone causing problems including obstruction to urine flow, surgical intervention is done.

Dr Rachna Pande, Specialist, internal medicine