the value of detected crystals in urine analysis

1. Crystalluria in Urinalysis
Dr. Afshin Ghalehgolab Behbahan
Pediatric Nephrologist
Tabriz Children’s Hospital

2. Crystalluria in Urinalysis
• It is common to find crystals on microscopic
examination of the urine (about 8%).
• the presence of crystals may be normal or
pathologic.
• Usually, the presence of crystals in the urine is
of limited clinical significance.

3. Supersaturation of the solute components of the
crystals must occur for crystallization to initiate.
• Factors affecting supersaturation, include;
– Solute concentration,
– Ionic strength (solubility),
– Urine pH,
– The presence of promoters or inhibitors.
• Causes of Supersaturation:
• Low fluid intake (dehydration),
• Hi dietary intake – Drug ingestion,
• Body metabolism,
• Prolonged interval between urine collection and urine
examination.

4. Crystalluria - Supersaturation
• In most instances, crystalluria is an occasional
finding without clinical importance because it
reflects transient supersaturation of urine, these
are called Common Crystals.
• Some crystals that almost always correlate with
a known pathology if they are seen in a child’s
urine, are called Pathological Crystals.

5. Urinary Crystals Classification:
Common (Normal) Crystals - Pathological (Abnormal) Crystals

6. Urinary Crystals Classification:
Common Crystals vs Pathological Crystals
Common Crystals

7. Urinary Crystals Classification:
Common Crystals vs Pathological Crystals
Pathological Crystals
Other Pathological Crystals include: Tyrosine, Leucine, Bilirubin
& Cholesterol Crystals.

8. However, Common Crystals May Be Seen In
Some Pathologic Situations As Well !
• persistent Calcium Oxalate crystalluria in repeated
samples of the same subject should raise the suspicion
of a possible disorder:
• Hypercalciuria,
• Hyperoxaluria,
• Hypocitraturia,
– Citrate is a crystallization inhibitor
• Ethylene Glycol Intoxication,
• Ingestion of the Exotic Star Fruit,
• Drug ingestion (Vitamin C, Naftidrofuryl Oxalate, & Orlistat)
Envelope or pyramid shaped
crystals

9. However, Common Crystals May Be Seen In
Some Pathologic Situations As Well !
• Persistent Uric Acid crystalluria in repeated
samples of the same subject should raise the
suspicion of a possible disorder:
• Hyperuricosuria (with or without Hyperuricemia)
• Acute Uric Acid Nephropathy,
• Persistent Dehydration

10. However, Common Crystals May Be Seen In
Some Pathologic Situations As Well !
• Persistent Triple phosphate, or Struvite crystalluria in
repeated samples of the same subject should raise the
suspicion of a possible disorder:
• Infections due to urease-producing bacteria
– typically associated with Proteus species
• Alkaline Urine
Triple phosphate crystals have the shape of
“coffin lids”: 3 to 4 to 6 – sided prism ,
composed of magnesium ammonium phosphate

11. Pathologic Crystals Seen in Pathologic Situations
• Cystine crystals are always abnormal and are
pathognomonic of the inherited disease: Cystinuria,
patients often have kidney stones.
• Found only in fresh urine, because if there is delay,
they are soluble and not seen.
• May also be seen in transient acute phase of
pyelonephritis
Flat, hexagonal plates with well-defined
edges, colorless, and highly retractile.

12. Pathologic Crystals Seen in Pathologic Situations
• Tyrosine and leucine crystals are also abnormal and
suggest liver disease.
• Bilirubin crystals are seen in All conditions associated
with Conjugated Hyperbilirubinemia and
Hyperbilirubinuria, such as Cholestasis.
Leucine crystalTyrosine crystals Bilirubin crystals

13. Pathologic Crystals Seen in Pathologic Situations
• Cholesterol crystals
– are found in patients with marked proteinuria.

14. Pathologic Crystals Seen in Pathologic Situations
• 2,8-dihydroxyadenine crystals
– are a highly sensitive marker of homozygotic deficiency of
the enzyme adenine phosphoribosyltransferase (APRT),
found in about 96% of untreated patients.

15. Association between Urine pH & Crystals
• I. Acidic urine crystals
• -Amorphous Urates,
• -Uric acid crystals,
• -Cystine crystals
• -Calcium Phosphate
• -Cholesterol
• -Ammonium Biurates
• -Tyrosine, Leucien, Bilirubin,
• -Calcium sulfates
• -Calcium urates
• -Calcium carbonate
• II. Acidic, Neutral, or slightly
alkaline Urine crystals
• - Calcium Oxalate crystals
• III. Alkaline, Neutral, or Slightly
acidic urine
• - Triple phosphates (Struvite)
• IV. Alkaline Urine Crystals
• - Amorphous phosphate
• - Calcium carbonate
• - Calcium phosphate

16. Drug Crystals in Urine
• As a general rule:
– one should always suspect drug crystalluria
when finds Atypical Crystals, because:
Most drugs cause atypical and/or
pleomorphic crystals, which differ remarkably
from common or pathological crystals

17. Drug Crystals in Urine
• Factors causing Drug-crystals precipitation in urine:
– Drug overdose,
– Rapid intravenous bolus administration,
– Hypoalbuminemia,
– Dehydration,
– Urine pH:
• Indinavir at pH > 6.0,
• Amoxicillin at pH ≤ 4.0 or >7.0 with “U” shaped behavior,
• Ciprofloxacin at pH>7.3

18. Drug Crystals in Urine
• If confirmed, this should always prompt the check of
renal function because acute renal failure can occur,
especially in patients with impaired renal function.
• When crystalluria is caused by drugs, this may be the
only urinary abnormality or it may be associated with:
– Hematuria (either gross or microscopic),
– Acute Tubular Necrosis caused by precipitation of
crystals within renal tubules,
– Obstructive uropathy caused by drug stones.

19. Drug Crystals in Urine

20. Drug Crystals in Urine
• If confirmed, this should always prompt the check of
renal function because acute renal failure can occur,
especially in patients with impaired renal function.
• It is advisable to:
– Withdraw the drug or decrease the dosage,
– Reestablish euvolemia,
– Stimulate a high urine flow,
– Manipulate urine pH in reverse direction

21. Drug Crystals in Urine