Nephrolithiasis

The manifestations of renal calculi are extremely variable. In many instances stones are carried in the kidneys for years without producing any symptoms. More commonly, a mild infection develops in the pelvis about the stone and gradually involves the cortex of the kidney until a severe pyelonephritis develops. If the stone is large, or several are present, the infection may progress to pyonephrosis, resulting in the destruction and ultimate loss of the kidney.

The size of a calculus varies from very small gravel to a large stag-horn stone which may fill the renal pelvis. Calcium oxalate stones are usually small, dark, rough and hard. They are more likely to occur in men between 20-30. Calcium phosphate stones tend to be soft, white, chalky and frequently stag-horn in shape. The biggest risk factor for kidney stones is not drinking enough fluids. Kidney stones are more likely to occur when less than 1 liter of urine is produced during a day.

Migration of a stone may cause obstruction with resultant stasis, infection and clinical manifestations. Persistent or repeated obstruction leads to pyonephrosis or hydronephrosis. When a stone enters and obstructs the ureter, renal colic occurs. There is excruciating pain which originates in the back of flank and radiates across the abdomen and into the groin, genitals and inner aspect of the thigh. There may be nausea, vomiting, sweating, frequency, urgency of urination, chills and shock.

To reveal kidney stones blood test is ordered for checking the levels of calcium, phosphorus and electrolyte. Urinalysis determines crystals and red blood cells in the urine. Examination reveals slight soreness over the involved kidney and ureter, spasm of the abdominal muscles, albuminuria and microscopic haematuria.

Intermittent or persistent obstruction to the flow of urine leads to stasis, infection, hydronephrosis and renal destruction if the obstruction is bilateral, anuria and uremia ensue.

Treatment depends on the type of stones and severity of the symptoms. Small calculi usually pass through urinary system on their own. Some people with severe pain from kidney stones should stay in the hospital and get fluids through the vein. Some medicines (antibiotics, diuretics, sodium bicarbonate) may be prescribed to prevent forming or help breaking down material that causes stones. Surgery is often needed if the calculus is too large to pass on its own or it blocks the urine flow causing an infection or kidney damage.

Exercise 6. Answer the following questions:

1. How are the stones carried in the kidneys for years?

2. In what case may the infection progress to pyonephrosis?

3. When does renal colic occur?

4. What may the migration of stone cause?

5. Where does the excruciating pain originate?

6. What does the examination of the kidneys reveal?

7. What are the symptoms of renal calculi?

8. What is the difference between calcium oxalate stones and calcium phosphate stones?

Exercise 7. Choose the correct definitions to the following terms: