Urinary Calculus

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Contents 1 More Specific Terms 2 Introduction 3 Etiology 4 Epidemiology 5 Genetics 6 Clinical-manifestations 7 Laboratory 8 Diagnostic-procedures 9 Radiology 10 Complications 11 Differential-diagnosis 12 Management 13 More General Terms 14 Additional Terms 15 References

More Specific Terms

• calcium stone
• cystine stone
• nephrocalcinosis
• struvite stone
• uric acid stone (urate nephropathy, gouty nephropathy)
• urinary calculus stone profile

Introduction

• Concretions of crystals in the urine, more commonly stones.

Etiology

• composition

• calcium oxalate*
• calcium phosphate*
• uric acid ( radiolucent)
• cystine (may be intermediate in radio-opacity)
• ammonium magnesium phosphate (struvite)
• less common

• xanthine
• oxypurinol

• predisposing factors

• dehydration
• stress
• supersaturation of urine with crystal
• alterations in inhibitors of crystal formation

• pH

• calcium phosphate & struvite stones form in alkaline urine
• uric acid & cystine stones for in acidic urine

• low citrate ( RTA type 1)
• pyrophosphates
• magnesium

• urine stasis from obstruction
• repeated infection by urease-containing organisms

• high urine pH
• Proteus, Klebsiella & others
• struvite stones
• staghorn calculus

• diet high in animal protein ( Atkin's diet)
• polycystic kidney disease
• medullary sponge kidney
• renal tubular acidisis (RTA) type 1
• pharmaceutical agents

• acetazolamide for glaucoma ( calcium phosphate)
• calcium carbonate ( milk alkali syndrome)
• allopurinol ( xanthine or oxypurinol stones)
• triamterene
• methoxyfluorane ( calcium oxalate)
• vitamin D, non thiazide diuretics, steroids ( hypercalciuria)
• indinavir
• chemotherapy (increased uric acid load)

• intestinal hyperoxaluria

• bowel surgery
• Crohn's disease
• ileostomy

• genetic predisposition: family history

• * calcium stones comprise 75% of all stones

Epidemiology

• 10% of people will develop urinary calculi at some point in their lives
• annual incidence is 0.1%
• men have twice the risk as females
• if untreated 50-75% will have recurrence within 7 years

Genetics

• susceptibility to uric acid nephrolithiasis caused by defect in ZNF365 gene

Clinical-manifestations

• acute flank pain

• costovertebral angle ( CVA) tenderness
• acute colic to dull, persistent pain

• nausea/vomiting
• pain not relieved by position
• fever &/or persistent UTI may suggest urinary calculi especially struvite
• hematuria (may be painless)

Laboratory

• urinalysis

• hematuria ( biphasic manifestation) [4]

• prevalence highest on the day symptoms begin then declines over several days, then increases
• absence of RBC does not rule out nephrolithiasis

• WBC
• a & b observed with calculi & UTI

• urine culture:

• urease-containing organisms (Proteus, Klebsiella)

• 24 hour urine:

• 24 hour urine calcium
• 24 hour urine creatinine
• 24 hour urine uric acid

• increased risk of uric acid stones if > 1000 mg/24

• phosphorous, citrate, oxalate, cystine

• serum calcium, serum phosphate, serum uric acid
• serum PTH
• stone profile

• calculus composition analysis
• inhibitor content
• 75-85% of stones contain calcium

Diagnostic-procedures

• abdominal ultrasound

• initial test in pregnant women
• detects distal ureteral calculi [9]

Radiology

• plain abdominal X-ray ( KUB) (most cost effective)
• computed tomography ( CT) of abdomen (without contrast)

• gold standard [3]

• intravenous pyelogram ( IVP)
• urography with nephrotomography

Complications

• may be an association between kidney stones & progression to chronic renal failure [3]

Differential-diagnosis

• cholecystitis
• appendicitis
• diverticulitis
• UTI concurrent with calculus
• urinary tract tumor
• acute renal failure suggests

• obstructive uropathy

• bilateral obstruction
• obstruction in a solitary kidney

• volume depletion
• sepsis

Management

• asymptomatic kidney stone found on imaging do not require urgent intervention
• treatment of symptomatic individuals

• pain control:

• NSAIDs may be preferable to opiates [5]
• parenteral ketoralac ( Toradol) for acute renal colic

• relief of nausea/vomiting
• rehydration with IV saline if volume depleted
• stone removal or passage

• stones < 5-6 mm in size usually pass spontaneously

• nifedipine SA 30 mg or tamsulosin 0.4 mg QD for 5-7 days may reduce ureteral spasms & diminish pain [6]
• tamsulosin superior to nifedipine [7], reduces median time of stone passage from 5 days to 3 days
• alfuzosin also reduces median stone passage time 8 days to 5 days & reduces pain
• corticosteroids reduce ureteral edema & facilitate passage of stones

• stones > 6 mm require surgery

• ureteroscopy

• stones in the distal ureter
• removal of stone fragments resulting from lithotripsy

• lithotripsy - stones < 1 cm in kidney or upper urinary tract
• percutaneous nephroscopic removal

• stones > 1 cm
• staghorn calculi
• cystine stones resistant to lithotripsy
• patients with urinary tract abnormalities

• open surgery

• indications for stone removal

• hydronephrosis
• unrelieved pain
• deteriorating renal function

• antibiotic therapy for concurrent UTI
• long-term antibiotics may be needed for large struvite stones

• prevention

• adequate hydration (> 2L/day)
• diet

• reduced animal protein ( uric acid stones)
• increased vegetable fiber
• decreased salt intake
• reduced dietary oxalate
• reduced calorie diet
• do not restrict calcium intake

• calcium restriction does not prevent stones, but may actually increase stone formation
• dietary calcium paradoxically decreases risk of calcium oxalate stone formation & recurrence [3]
• calcium restriction contributes to osteoporosis

• increase urine pH

• pH > 7 increases uric acid solubility
• pH > 8 increases cystine solubility

• thiazide diuretics reduce urinary excretion of calcium
• replacement of inhibitor substances

• potassium citrate [8]
• pyrophosphate
• magnesium oxide

• allopurinol decreases formation of uric acid

More General Terms

• urologic disease

Additional Terms

• 2,8-dihyroxyadenuria
• crystals in urine
• hereditary nephrolithiasis
• idiopathic hypercalciuria
• xanthinuria

References

1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 533-34
2. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 614-16
3. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
4. Journal Watch 23(23):184-85, 2003 Kobayashi T et al, J Urol, 170:1093, 2003 PMID: [1]
5. Journal Watch 24(16):125, 2004 Holdgate A, Pollock T. Systematic review of the relative efficacy of non-steroidal anti-inflammatory drugs and opioids in the treatment of acute renal colic. BMJ. 2004 Jun 12;328(7453):1401. Epub 2004 Jun 03. Review. <PubMed> PMID: [2] <Internet> [3]
6. Prescriber's Letter 11(9): 2004 Use of Nifedipine or Tamsulosin for Kidney Stones Detail-Document#: [4] (subscription needed) [5]
7. Journal Watch 25(17):135, 2005 Dellabella M, Milanese G, Muzzonigro G. Randomized trial of the efficacy of tamsulosin, nifedipine and phloroglucinol in medical expulsive therapy for distal ureteral calculi. J Urol. 2005 Jul;174(1):167-72. PMID: [6]
8. Robinson MR et al. Impact of long-term potassium citrate therapy on urinary profiles and recurrent stone formation. J Urol 2009 Mar; 181:1145. PMID: [7]
9. Moesbergen TC et al. Distal ureteral calculi: US follow-up. Radiology 2011 Aug; 260:575. PMID: [8]
10. Kidney Stones: NIH Institute and Center Resources [9]
11. National Guideline Clearinghouse Acute onset flank pain, suspicion of stone disease. American College of Radiology ngc-guideline: [10]
    - 2007 guideline for the management of ureteral calculi. American Urological Association Education and Research, Inc. ngc-guideline: [11]
    - Guidelines on urolithiasis. European Association of Urology ngc-guideline: [12]

urinary calculus (stone, nephrolithiasis, urolithiasis)