Crystals

Question 1

What are urine crystals and how are they formed?

Answer 1

Urine crystals are solid precipitates of solutes in the urine.
Form when solute concentration is high, urine pH favors crystallization, and/or temperature is low.
Can be normal or indicate underlying disease or metabolic disorder.

Question 2

Which factor influence crystal formation in urine

Answer 2

pH of urine (acidic vs. alkaline)
Solute concentration (e.g., calcium, oxalate, uric acid)
Temperature (lower temperatures favor crystallization)
Urine stasis or dehydration

Question 3

Calcium oxalate crystals

Answer 3

Appearance: Envelope-shaped (dihydrate), dumbbell (monohydrate)
pH: Found in acidic, neutral, or alkaline urine
Significance: Often normal; may be seen with oxalate-rich foods or ethylene glycol poisoning
Can form stones

Question 4

Uric Acid Crystals

Answer 4

Appearance: Rhomboid, rosette, or diamond shapes; yellow-brown
pH: Acidic urine
Significance: May be normal or indicate hyperuricemia, gout, or tumor lysis syndrome
Can form stones

Question 5

Triple Phosphate Crystals

Answer 5

Appearance: “Coffin-lid” shape
pH: Alkaline urine
Significance: Seen in UTIs with urease-producing bacteria (e.g., Proteus)
Can form staghorn calculi

Question 6

Calcium phosphate crystals

Answer 6

Appearance: Rosette or star-shaped prisms
pH: Alkaline to neutral
Significance: May be normal or associated with alkaline urine, renal tubular acidosis, or stones

Question 7

Amorphous urates

Answer 7

Appearance: Granular, reddish-brown precipitate
pH: Acidic urine
Significance: Common in acidic, concentrated urine; not clinically significant

Question 8

Amorphous phosphates

Answer 8

Appearance: Colorless granular precipitate
pH: Alkaline urine
Significance: Common in healthy individuals; not clinically significant

Question 9

Cysteine Crystals

Answer 9

Appearance: Colorless, hexagonal plates
pH: Acidic urine
Significance: Seen in cystinuria (genetic disorder affecting amino acid reabsorption)
Always pathological

Question 10

Tyrosine Crystal

Answer 10

Appearance: Fine, silky needles in sheaves
pH: Acidic urine
Significance: Seen in severe liver disease, e.g., tyrosinemia
Always pathological

Question 11

Leucine Crystals

Answer 11

Appearance: Yellow-brown, concentric circles with radial striations
pH: Acidic urine
Significance: Seen in severe liver disease, e.g., maple syrup urine disease or tyrosinemia
Always pathological

Question 12

Cholesterol Crystals

Answer 12

Appearance: Rectangular plates with notched corners
pH: Acidic urine
Significance: Seen in nephrotic syndrome
May be accompanied by fatty casts or oval fat bodies

Question 13

Bilirubin Crystals

Answer 13

Appearance: Fine needles or granules; yellow-brown
pH: Acidic urine
Significance: Seen in liver disease, biliary obstruction, or hepatitis
Often with positive bilirubin dipstick