CRYSTALS - NORMAL ALKALINE CYRSTALS

Crystaluria

Excretion of crystals in urine, resulting from the precipitation of urine solutes (salts, organic compounds).

Calculi

Kidney stones

Renal Tubular of bladder

Site formation of crystals

pH of urine

most important determinant for crystals

Acidic pH

favors uric acid, cystine, calcium oxalate crystals

Alkaline pH

favors triple phosphate, calcium phosphate, ammonium biurate crystals

Solute concentration

Higher concentration promotes precipitation

Temperature

Lower temperature enhances crystal formation (the reason why refrigerated urine samples often show crystals)

Amorphous phosphates

Fine, colorless to white, granular precipitate. settles as WHITEY LACY DEPOSIT in alakline pH above 6.5. Appear tiny, colorless granules (may be mistaken for bacteria)

Amorphous phosphate

Most common cause of turbidity in alkaline specimen and is soluble in ACETIC ACID

Ammonium biurate

Characteristic “THORNY APPLE” spicules. Yellow-brown, spherical bodies with

irregular projections. Common in old or poorly preserved alkaline urine.

Triple phosphate

Colorless, prism-shaped crystals with the classic “COFFIN LID” look. May appear as fern-leaf or feather shapes when disintegrating. Frequently associated with UTIs caused by PROTEUS

Magnesium Ammon Phosphate

Colorless, rhomboid plates or long prisms. Less common than triple phosphates.

Calcium Phosphate

May be seen in renal calculi

Apatite (hydroxyapatite)

Fine, colorless granules or rods

Dibasic calcium phosphate

Colorless, flat plates or thin prisms arranged in rosette clusters.

Monobasic calcium phosphate

irregular, granular sheets or plates

Calcium carbonate

Small, colorless DUMB BELL or spherical forms (often in pairs, like tetrads). Produces effervescence (CO₂ bubbles) upon addition of acetic acid.