Kidney stones is a common health problem and affects about 1 in 11 persons.
How are stones formed?
When the concentration of certain substances like Calcium, Oxalate, Uric Acid and Cystine are high in urine, they form crystals which attach to the kidney and gradually increase in size to form a stone.
What are the types of stones?
80%of stones are Calcium stones, mostly calcium oxalate and few calcium phosphates.
Rest of them are – Uric acid stones, Infection stones and Cystine stones.
Risk Factors for Stone Formation:
- Certain diseases, medications, dietary habits increase the likelihood of stone formation like-
- Excessive amount of Calcium or Oxalate in urine.
- Dietary factors like low calcium in diet, high in oxalates, high animal protein or high sodium in diet.
- Drinking less water and fluids causing dehydration.
- Excessive supplements of calcium, Vitamin D and Vitamin C.
- Stones are more common in people suffering from diabetes, hypertension, obesity, gout, hyperparathyroidism, or who have undergone gastric bypass or bariatric surgery.
- Hereditary factor: Certain stones like cysteine occur amongst family members and indicate genetic disorders.
- Recurrence of stones- if one has kidney stones in the past there is high risk of developing another in future, more so in men. 10 – 30% of men will develop stones again in 5 years.
Depends on the size and location of the stones.
The most common symptom caused by stones is pain in the flank or lower abdomen which may move to the groin. Pain is most common when passing a stone. Waves of severe excruciating pain are called ‘renal colic’ and last for 20-60 minutes.
There may be difficulty in urination, blood in urine or vomiting.
Gravel/sand may be passed in urine.
The stone may remain in the urinary tract and obstruct the flow causing pain.
Small stones in the kidney which do not cause obstruction may cause no symptoms at all.
Renal stones are diagnosed by ultrasonography or CT scan. X-Ray and intravenous pyelography are also useful modalities.
CT scan is more accurate but exposes the patient to radiation.
To know the type of stone, a 24-hour urine estimation of calcium/oxalate/uric acid and citrate is essential.
A urine examination is helpful to see if there is any infection or if the urine is acidic or alkaline.
Treatment of stones depends on the size and location of stone in the urinary tract.
Those less than 5mm usually passout without specific treatment. An increase in fluid intake and pain medications are required.
Severe episodes of renal colic require hospitalisation and treatment with intravenous fluids and other drugs.
Larger stones i.e. more than 9mm may require surgical removal, by percutaneous nephrolithotomy or Shock-wave lithotripsy.
Approximately 10-20 % of all stones require surgery.
- Kidney stones can be prevented by making few changes in the diet and habits
- Drinking right amount of water to maintain good urinary flow. One should drink at least 7- 8 glasses of water per day.
- Diet should have adequate amount of calcium. Milk, yoghurt, lentils, oranges and other dairy products are rich in calcium
- Eat right amount of protein- daily protein needs are usually met with 2-3 servings per day.
- Reduce amount of sodium in diet to 2-3 gms. Limit processed foods like hot dogs, sausages, dry soup, pickles and various convenience mixes as they contain excessive amounts of salt
- Avoid excessive vitamin C supplements as oxalate is produced from vitamin C and large amounts may increase amount of oxalate content of urine.
- Avoid foods which are high in oxalates like spinach, almonds, peanuts, nut butters, blueberries.
- Do not take Vitamin D supplements without prescription of a physician
- Controlling blood sugar, blood pressure, body weight by regular exercise are all helpful to reduce stone formation.
Dr. Deepak Shankar Ray
Consultant Nephrologist and Chief of Renal Transplant
Rabindranath Tagore International Institute of Cardiac Sciences, Mukundapur, Kolkata