Nephrolithiasis - Kidney Stone

  • Diagnosis
  • Algorithms
  • Screening
  • Monitoring
  • Background
  • Pediatrics
  • Lab Tests
  • References
  • Related Content

Indications for Testing

  • Patient with symptoms of a stone

Laboratory Testing

  • Initial testing
    • CBC – evaluate for concomitant infection
    • Electrolytes – evaluate for electrolyte abnormalities
    • Blood urea nitrogen (BUN)/creatinine – evaluate for obstructive renal pathology
    • Urinalysis with possible urine culture – evaluate for concomitant urinary tract infection
  • 24-hour urine evaluation – use panel testing for most patients
    • Not usually performed with first stone (exception with children)
      • Usually includes electrolyte analysis (eg, sodium) and metabolic analysis (eg, oxalate and calcium)
    • May delay risk assessment until stone disease recurs
    • Two different specimens recommended
  • Serum – uric acid, ionized calcium, and parathyroid hormone-related peptide (PTH)
    • PTH testing may be reserved for recurrent disease unless primary hypoparathyroidism is suspected
  • Amino acids analysis – evaluate when cystinuria is suspected or for those with cystine stones
  • Stone analysis
    • Repeat if lack of response to therapy since stone composition may change

Imaging Studies

  • Helical CT scan can confirm presence and location of stones
    • May help assess stone burden and risk of recurrence

Differential Diagnosis

  • Urinary tract infection
  • Ectopic pregnancy
  • Musculoskeletal pain
  • Ovarian cyst rupture
  • Ovarian torsion
  • Peritonitis
  • Prostatitis
  • Acute pyelonephritis
  • Interstitial cystitis
  • Groin hernia

Nephrolithiasis Testing Algorithm

  • No evidence to support screening for stones in asymptomatic patients
  • Usually unnecessary in first-time stone former
  • If performed, usually includes a minimum of the following
    • Assessment within 6 months after treatment begins or changes; thereafter annually, depending on stone activity (American Urological Association, 2014)
    • 24-hour urine – kidney stone panel testing
      • Should include testing for calcium oxalate sodium, uric acid, citric acid, phosphorus, creatinine
      • Quantitative cystine in patients with cystinuria
    • Serum – urea nitrogen, creatinine, and ionized calcium

Nephrolithiasis is a worldwide problem that accounts for significant morbidity and expense.

Epidemiology

  • Prevalence – 1-5/1,000
    • 1/11 affected during lifetime (Pearle, 2014)
  • Age – peaks in 20s
  • Sex – M>F, 2-3:1
  • Ethnicity – Caucasian men have highest incidence
  • Geographic – hotter and drier climates

Risk Factors

Clinical Presentation

  • Acute, colicky flank pain radiating into the pelvis and genitalia
  • Nausea and vomiting
  • Urinary urgency, frequency, and dysuria may develop with stone passage
  • Hematuria – present in 90% of patients

Prevention

  • All stones – maintain urine volume ≥2.5 L/day
  • Uric acid stones – limit intake of nondairy protein, allopurinol (Agency for Healthcare Research and Quality [AHRQ], 2013)
  • Cystine stones – limit intake of protein and salt
  • Calcium oxalate stones (AHRQ, 2013; American Urological Association, 2014)
    • Increase intake of fluid
    • Reduce consumption of soft drinks
    • Thiazide diuretics
    • Citrate pharmacotherapy if urinary citrate is low
    • Reduce sodium and animal protein
    • If oxalate is relatively high – limit oxalate and use dairy products at mealtime to enhance binding of oxalate and calcium in gastrointestinal tract

Clinical Background

Epidemiology

  • Incidence – 4.7/100,000 hospitalized
  • Lower than in adults

Clinical Presentation

  • Flank pain, abdominal pain
  • <5 years of age – nonspecific; nausea, emesis
  • Blood in urine, dysuria, urgency

Diagnosis

Indications for Testing

  • Patient with suspicion for stone

Laboratory Testing

  • Initial testing
    • CBC – evaluate for concomitant infection
    • Electrolytes – evaluate for electrolyte abnormalities
    • Blood urea nitrogen (BUN)/creatinine – evaluate for obstructive renal pathology
    • Urinalysis with possible urine culture – evaluate for concomitant urinary tract infection
  • 24-hour urine evaluation
    • May delay this risk assessment until stone disease recurs
    • Initial testing should include 2 different specimens
    • Recommended in first episode due to high risk of metabolic problems underlying stone
  • Amino acids analysis
    • Evaluate for cystinuria in patients with elevated urine cystine – more common in children with nephrolithiasis

Monitoring

  • More important in children, even with first-time stone former
    • >75% of stones in children are secondary to metabolic problems
  • Usually includes the following
    • Assessment within 6 months after treatment begins or changes
    • 24-hour urine evaluation – kidney stone panels to assess
      • Should include testing for calcium oxalate, sodium, uric acid, citric acid, phosphorus, creatinine
      • Quantitative urine cystine or urine amino acids analysis in patients with cystinuria
    • Serum – urea nitrogen, creatinine, and ionized calcium

Indications for Laboratory Testing

Tests generally appear in the order most useful for common clinical situations.
Click on number for test-specific information in the ARUP Laboratory Test Directory

Calculi Risk Assessment, Urine 2008708
Method: Quantitative Spectrophotometry/Quantitative Enzymatic/Quantitative Ion-Selective Electrode

Supersaturation Profile, Urine 2008771
Method: Quantitative Spectrophotometry/Quantitative Enzymatic/Quantitative Ion-Selective Electrode

Limitations

Assessment for risk of magnesium ammonium phosphate (struvite) calculi is not included in this profile

Does not test for urine cystine

Follow Up

If magnesium ammonium phosphate calculi are suspected, order plasma ammonia testing

If cystine calculi are suspected, order cystinuria panel, cystine quantitative urine or amino acids quantitative urine tests

Kidney Stone Risk Panel, Urine 0020843
Method: Quantitative Spectrophotometry/Quantitative Enzymatic

Cystinuria Panel 0081105
Method: Quantitative Liquid Chromatography/Tandem Mass Spectrometry

Cystine Quantitative, Urine 0081106
Method: Liquid Chromatography/Tandem Mass Spectrometry

Amino Acids Quantitative by LC-MS/MS, Urine 2009419
Method: Quantitative Liquid Chromatography/Tandem Mass Spectrometry

Calculi (Stone) Analysis 0099460
Method: Quantitative Reflectance Fourier Transform Infrared Spectroscopy/Quantitative Polarizing Microscopy

Calculi (Stone) Analysis with Photo 2005231
Method: Quantitative Reflectance Fourier Transform Infrared Spectroscopy/Quantitative Polarizing Microscopy

Additional Tests Available

CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Comments

Evaluate for concomitant infection

Renal Function Panel 0020144
Method: Quantitative Chemiluminescent Immunoassay/Quantitative Enzyme-Linked Immunosorbent Assay

Comments

Evaluate for obstructive pathology

Panel includes albumin, calcium, carbon dioxide, creatinine, chloride, glucose, phosphorous, potassium, sodium, and BUN

Urinalysis, Complete 0020350
Method: Reflectance Spectrophotometry/Microscopy

Comments

Detect urinary tract abnormalities, including crystals

Urine Culture 0060131
Method: Culture/Identification

Comments

Evaluate for concomitant infection

Creatinine, Serum or Plasma 0020025
Method: Quantitative Enzymatic

Creatinine, 24-Hour Urine 0020473
Method: Quantitative Spectrophotometry

Oxalate, Urine 0020482
Method: Quantitative Spectrophotometry

Oxalate, Plasma 2011697
Method: Quantitative Spectrophotometry

Citric Acid, Urine 0020852
Method: Quantitative Enzymatic

Urea Nitrogen, Serum or Plasma 0020023
Method: Quantitative Spectrophotometry

Uric Acid, Serum or Plasma 0020026
Method: Quantitative Spectrophotometry

Comments

Assay interference (negative) may be observed when high concentrations of N-acetylcysteine (NAC) are present

Negative interference has also been reported with NAPQI (an acetaminophen metabolite) but only when concentrations are at or above those expected during acetaminophen overdose

Calcium, Ionized, Serum 0020135
Method: Ion-Selective Electrode/pH Electrode

Parathyroid Hormone-Related Peptide (PTHrP) by LC-MS/MS, Plasma 2010677
Method: Quantitative High Performance Liquid Chromatography-Tandem Mass Spectrometry

Comments

Amino (N)- and carboxy (C)-terminus PTHrP fragments, such as those produced by some patients with renal insufficiency, do not interfere with this assay

Guidelines

Fink H, Wilt T, Eidman K, Garimella P, MacDonald R, Rutks I, Brasure M, Kane R, Ouellette J, Monga M. Medical management to prevent recurrent nephrolithiasis in adults: a systematic review for an American College of Physicians Clinical Guideline. Ann Intern Med. 2013; 158(7): 535-43. PubMed

Fink HA, Wilt TJ, Eidman KE, Garimella PS, MacDonald R, Rutks IR, Brasure M, Kane RL, Monga M. Recurrent Nephrolithiasis in Adults: Comparative Effectiveness of Preventive Medical Strategies [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US) 2012; :PubMed

Pearle M, Goldfarb D, Assimos D, Curhan G, Denu-Ciocca C, Matlaga B, Monga M, Penniston K, Preminger G, Turk T, White J, American Urological Assocation. Medical management of kidney stones: AUA guideline. J Urol. 2014; 192(2): 316-24. PubMed

General References

Brener Z, Winchester J, Salman H, Bergman M. Nephrolithiasis: evaluation and management. South Med J. 2011; 104(2): 133-9. PubMed

Frassetto L, Kohlstadt I. Treatment and prevention of kidney stones: an update. Am Fam Physician. 2011; 84(11): 1234-42. PubMed

Goldfarb D. In the clinic. Nephrolithiasis. Ann Intern Med. 2009; 151(3): ITC2. PubMed

Sakhaee K, Maalouf N, Sinnott B. Clinical review. Kidney stones 2012: pathogenesis, diagnosis, and management. J Clin Endocrinol Metab. 2012; 97(6): 1847-60. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Gabrielsen S, Laciak R, Frank E, McFadden M, Bates C, Oottamasathien S, Hamilton B, Wallis C. Pediatric urinary stone composition in the United States. J Urol. 2012; 187(6): 2182-7. PubMed

Medical Reviewers

Last Update: January 2016