M. N. Jalalian

Faculty of Medicine

Tehran University of Medical Sciences

Definition

Presence of calculi (stones) in the kidney or collecting system

Usually small (2-12 mm), solid, crystalline concretions

Calcium salts, uric acid, cystine, or struvite

Stones < 0.5 cm without symptoms

Larger calculi cause pain and obstruction

Staghorn calculi (struvite, cystine, and uric acid) can grow as large as renal pelvis

Epidemiology

3rd common problem of urinary tract

In the U.S., ~13% of men and 7% of women

during their lifetime Prevalence is increasing throughout the industrialized world.

Sex

Calcium and uric acid More common in men○ Calcium stones

Male-to-female ratio, 2-3:1

Onset in the third to fourth decades of life

Struvite stones are more common in women○ Male-to-female ratio, 1:3

Risk Factors

Family history: calcium and uric stones

UTI with urease-producing bacteria

Diet high in oxalate, purine, and calcium

Poor fluid intake

Gout

Chronic bladder catheterization: struvite stones

Prior stone formation 50% of people who form a single calcium stone form

another within the subsequent decade

Etiology

Types of Stones

Calcium stones

○ Calcium oxalate and calcium phosphate

stones

Uric acid stones

Struvite stones

Cystine stones

Other types

○ Xanthine, Indinavir, etc.

EtiologyCalcium stones

75-85% of renal stones

Major causes

Hypercalciuria

○ Absorptive

Type I: relatively unresponsive to dietary modifications (15%)

- Treatment: Cellulose phosphate, thiazide diuretics (limited)

Type II: responds to moderate dietary calcium restriction.

Type III: renal phosphate leak (5%)

- Hypophosphatemia ↑ activation of vitamin D-3 ↑

intestinal absorption ↑ urinary excretion

- Treatment: orthophosphate

Hypercalciuria…

○ Resorptive hypercalciuria

(hyperparathyroidism)

5-10%

Resection of parathyroid adenoma

○ Renal leak hypercalciuria

Defect in kidney

Mild hypocalcemia and secondary

hyperparathyroidism

Treatment: thiazide diuretics (long-term)

EtiologyCalcium stones

Hyperuricosuria (20%)

secondary to dietary excesses or uric

acid metabolic defects

pH > 5.5

Treatment

○ Limited purine in diet

○ Allopurinol

Hyperoxaluria (20%)

Small-bowel disease

○ Causing fat malabsorption

Dramatic effect

Treatment

○ Oxalate binders (Ca, Mg, other cations)

○ dietary oxalate restriction

Hypocitraturia (20-40%)

Can be primary or secondary

EtiologyStruvite stones

5-10%

Magnesium-ammonium-phosphate (MAP)

Common in women with recurrent UTI

urease-producing bacteria

○ Proteus, Pseudomonas, or Providencia species

pH > 7.2 (Nl = 5.85)

EtiologyUric acid stones

5-10%

Hyperuricosuria

Gout

Myeloproliferative syndromes

Chemotherapy

high purine intake

pH < 5.5

Treatment: alkali therapy,, allopurinol

Etiology

Cystine stones

1-3%

Cystinuria

○ autosomal recessive disorder

○ defective proximal tubular and jejunal transport of

cystine, lysine, arginine, and ornithine

○ Clinical disease due to insolubility of cystine

Drug-induced stone disease

Indinavir

tazanavir; triamterene; silicate

Clinical Presentation

Pain Usually very severe

Sudden onset

Localized to the flank, with radiation to the groin

Colicky

Hematuria

Infection

Fever

Nausea and vomiting

Patient constantly moving

Differential Diagnosis

Pyelonephritis

Acute abdomen

Gynecologic problems

Diverticulitis

Abdominal aortic aneurysm

Aortic dissection

Appendicitis

Biliary colic

Perforating duodenal ulcer

Viral gastroenteritis

Acute pancreatitis

Urinary tract infection

Diagnostic Approach

Clinical suspicion

Rapid imaging

Ultrasonography

Noncontrast spiral CT scanning

likelihood of passing spontaneously

< 4 mm: 80%

4-6 mm: 60%

>6 mm: 20%

U/A

Imaging

Plain abdominal radiography

KUB radiography

size, shape, and location of urinary calculi

Radiopaque

○ Calcium-containing stones,

○ Cystine

○ struvite stones are

Radiolucent

○ pure uric acid

Spiral CT without contrast

Preferred tool when KUB is nondiagnostic

Advantages

○ More sensitive

○ Identify other pathology

Disadvantages

○ More costly than intravenous pyelography

Ultrasonography

Advantages

○ Detects uric acid or cystine stones (not in KUB)

○ Inexpensive

○ Readily available

Disadvantages

○ Ureteral calculi, especially in the distal ureter,

and stones < 5 mm not easily observed

Intravenous pyelography

Formerly the standard (for size and location)

Advantages

○ Both anatomic and functional

○ Stones vs calcification

Disadvantages

○ Intensive and time consuming if severe

obstruction

○ Requires bowel preparation for optimal results

○ Allergic and nephrotoxic contrast material

Treatment Approach

Goal : Remove existing stones and prevent

stone recurrence

Treatment depends on:

Location of the stone

Nature of the stone

Extent of obstruction

Function of affected and unaffected kidney

Presence or absence of urinary tract infection

Progress of stone passage

Risk of operation or anesthesia

Stones already present

Combined medical and surgical approach

Oral α1-adrenergic blockers

○ Relax ureteral muscle

○ Reduce time to stone passage

○ Reduce need for surgical removal of small

stones

Indications for stone removal

A stone, usually >5mm, that does not

pass spontaneously

Severe obstruction

Infection

Intractable pain

Serious bleeding

Management of renal colic

Hydration

Pain control Parenteral: morphine sulfate and/or

intravenous NSAID (e.g.,ketorolac)

Oral: narcotic (codeine, oxycodone, hydrocodone) plus acetaminophen together with an NSAID, such as ibuprofen

Antiemetic agents (e.g.,metoclopramide orprochlorperazine)

Strain urine

Antibiotics, if infection is suspected

Agents to relax the ureters

α1-blockers (e.g.,tamsulosin 0.4 mg PO daily

30 minutes after a meal)○ Faster and fewer hospitalization

Calcium-channel blockers

When to hospitalize

Intractable pain requiring parenteral

medications

Persistent vomiting

Obstruction with infection

Solitary kidney with obstruction

When to refer to urologist

Obstruction

Stone size > 6 mm

Infection

Failure to progress

Solitary kidney

Pregnancy

Severe renal disease

Thank you for your

attention