Kidney stones are a common problem worldwide with substantial morbidities and economic costs. Medical therapy reduces stone recurrence significantly.

1. M. N. Jalalian
Faculty of Medicine
Tehran University of Medical
Sciences

2. 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

4. 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

5. 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

6. Etiology
 Types of Stones
 Calcium stones
○ Calcium oxalate and calcium phosphate
stones
 Uric acid stones
 Struvite stones
 Cystine stones
 Other types
○ Xanthine, Indinavir, etc.

7. Etiology
Calcium 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

8.  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)

9. Etiology
Calcium stones
 Hyperuricosuria (20%)
 secondary to dietary excesses or uric
acid metabolic defects
 pH > 5.5
 Treatment
○ Limited purine in diet
○ Allopurinol

10.  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

11. Etiology
Struvite 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)

12. Etiology
Uric acid stones
 5-10%
 Hyperuricosuria
 Gout
 Myeloproliferative syndromes
 Chemotherapy
 high purine intake
 pH < 5.5
 Treatment: alkali therapy,, allopurinol

13. 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

14. 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

15. 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

16. 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

17. 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

19.  Spiral CT without contrast
 Preferred tool when KUB is nondiagnostic
 Advantages
○ More sensitive
○ Identify other pathology
 Disadvantages
○ More costly than intravenous pyelography

20.  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

21.  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

22. 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

23.  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

24. Indications for stone removal
 A stone, usually >5mm, that does not
pass spontaneously
 Severe obstruction
 Infection
 Intractable pain
 Serious bleeding

25. 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 orprochlorperazi
ne)

26.  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

27. When to hospitalize
 Intractable pain requiring parenteral
medications
 Persistent vomiting
 Obstruction with infection
 Solitary kidney with obstruction

28. When to refer to urologist
 Obstruction
 Stone size > 6 mm
 Infection
 Failure to progress
 Solitary kidney
 Pregnancy
 Severe renal disease

29. Thank you for your
attention