What Are Kidney Stones?
 

Kidney stones, also called nephrolithiasis, are hard deposits that form when certain substances in the urine become concentrated and crystallize. Stones can remain within the kidney or travel into the ureter, the tube that carries urine from the kidney to the bladder.
 

Many kidney stones are small enough to pass naturally. However, larger stones or stones that become lodged in the urinary tract can block the flow of urine and sometimes require medical treatment.
 

What Causes Kidney Stones?
 

Kidney stones form when the urine contains high concentrations of substances that can form crystals. Not drinking enough fluids is one of the biggest risk factors because it produces more concentrated urine.

People who have had one kidney stone are at increased risk of developing additional stones in the future.
 

Types of Kidney Stones

Calcium Stones
 

Calcium stones are the most common type of kidney stone. Most are composed of calcium oxalate, although calcium phosphate stones also occur. Risk factors include:
 

• High sodium intake (sodium increases calcium urinary excretion)

• High urinary calcium (idiopathic despite often normal serum levels, high sodium intake, high vitamin d intake, high calcium intake especially with supplementation and without food, loop diuretics, primary hyperparathyroidism, high bone turnover disorders)

• Low calcium dietary intake (calcium binds to oxalate in gut)

• High oxalate sources (spinach, rhubarb, beats, nuts, chocolate, wheat bran)

• Chronic dehydration

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Uric Acid Stones
 

Uric acid stones develop when the urine is persistently acidic. Risk factors can include:
 

• Gout or elevated uric acid

• Metabolic syndrome

• Obesity

• Diabetes

• High intake of purine-rich foods (red meat, seafood)

• Chronic dehydration
   

Struvite Stones
 

Struvite stones are associated with urinary tract infections or colonization with certain bacteria that make the urine alkaline (Proteus mirabilis, some Klebsiella species,...). These stones can grow rapidly and may become very large. 

Cystine Stones
 

Cystine stones are uncommon and occur in people with cystinuria, an inherited disorder that causes excessive cystine to enter the urine.
 

They often begin at a younger age and have a tendency to recur.

What Are the Symptoms?
 

A stone located within the kidney may cause no symptoms at all. Symptoms commonly develop when a stone enters the ureter and interferes with urine flow.

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The classic symptom is sudden, severe pain, often called renal colic. This pain commonly:
 

• Begins in the side or back below the ribs

• Can be extremely intense

• Comes in waves or fluctuates in intensity

• May travel toward the lower abdomen or groin

• May move as the stone travels through the urinary tract

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Other symptoms may include:
 

• Blood in the urine

• Nausea or vomiting

• Pain or burning with urination

• Urinary urgency or frequency

• Lower abdominal or groin discomfort

How Are Kidney Stones Diagnosed?
 

Your healthcare provider will consider your symptoms, medical history, physical examination, and testing.

Urine Testing
 

A urinalysis may detect:

• Blood in the urine

• Signs of infection

• Crystals (with microscopy) 

• Urine acidity (pH)

Blood Testing
 

Blood tests may be used to evaluate:

• Kidney function

• Electrolytes

• Calcium

• Uric acid

• Signs of infection or other abnormalities

Imaging
 

Noncontrast CT scan. Sometimes ultrasound. Some large stones may be seen on xray, except uric acid ones. 

Stone Analysis
 

Your healthcare provider may recommend urinating through a stone strainer.

If the stone is recovered, laboratory analysis can determine its composition and help guide strategies to prevent future stones.

How Are Kidney Stones Treated?

-Treatment for small stones (≤5-10 mm) without infection or obstruction, especially near the distal ureter, may include up to a :
 

Pain Management, Fluids, Hydration, Alpha Blockers (tamsulosin) help relax smooth muscle in the ureter 

-Treatment for larger stones (>10 mm) or those causing obstruction may include:

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Shock Wave Lithotripsy

Extracorporeal shock wave lithotripsy (ESWL) 

Ureteroscopy, sometimes w/ laser and temporary stent 

Percutaneous Nephrolithotomy
 

-Uric acid stones can sometimes be dissolved by medications that make the urine less acidic.
 

-Thiazide diuretics may help decrease the recurrence of calcium stones in some people by decreasing urinary calcium excretion.