Kidney Stones

Kidney Stones

A kidney stone is a solid mass formed by tiny crystals, which may occur singularly or in multiples within the kidney or ureter.

Causes, Incidence, and Risk Factors

Kidney stones are prevalent, with certain types showing familial tendencies and even affecting premature infants. They are diverse in origin, depending on the stone type.

• Calcium stones, most common in men aged 20-30, result from the combination of calcium with substances like oxalate, phosphate, or carbonate. Oxalate, abundant in foods like spinach and certain vitamin C supplements, poses a notable risk. Conditions affecting the small intestine increase susceptibility to these stones.

• Cystine stones may develop in individuals with cystinuria, a hereditary disorder affecting both genders.

• Struvite stones, predominantly seen in women with urinary tract infections, can grow sizable and obstruct kidney, ureter, or bladder function.

• Uric acid stones, more prevalent in men and associated with gout or chemotherapy, are another variant.

• Other substances such as certain medications (acyclovir, indinavir, and triamterene) can also precipitate stone formation.

Insufficient fluid intake is the primary risk factor for kidney stones, with those producing less than 1 liter of urine daily being particularly susceptible.

Symptoms

Symptoms often manifest when stones obstruct urine flow through the ureters into the bladder, typically presenting as sudden and severe pain:

• Pain may originate in the abdominal or back region, subsequently radiating to the groin or testicles.

Other symptoms may include abnormal urine color, blood in the urine, chills, fever, nausea, and vomiting.

Signs and Tests

Physical examination may reveal tenderness in the abdomen or back. Diagnostic tests include:

• Blood tests to assess levels of calcium, phosphorus, uric acid, and electrolytes
• Kidney function tests
• Urinalysis to detect crystals and red blood cells
• Imaging studies like abdominal CT scans, MRI, x-rays, intravenous pyelogram (IVP), kidney ultrasound, or retrograde pyelogram to visualize stones or blockages.

Treatment

Treatment varies based on stone type and symptom severity. Small stones typically pass naturally, with urine straining recommended to capture and analyze stones.

Hydration, typically 6-8 glasses of water daily, encourages increased urine production. Pain management may require narcotic analgesics, and severe cases may necessitate hospitalization and intravenous fluids.

Medications may be prescribed to prevent stone formation or aid in stone breakdown and removal, including allopurinol for uric acid stones and antibiotics for struvite stones. Surgical intervention becomes necessary for large or problematic stones, with less invasive techniques preferred:

• Extracorporeal shock-wave lithotripsy breaks up smaller stones using sound or shock waves.
• Percutaneous nephrolithotomy removes large stones through a small surgical incision.
• Ureteroscopy addresses stones in the lower urinary tract.
• Open surgery (nephrolithotomy) remains a last resort.

Prognosis

While kidney stones are painful, they can typically be managed without lasting damage. Recurrence is common without proper identification and treatment of underlying causes. Delayed treatment may result in kidney damage or other complications.