NORMAL URINARY ACID CRYSTALS

Factors that contribute to crystal formation

• pH

• Solute concentration

• Temperature (precipitates at lower temperature)

Most valuable aid in crystal identification?

the urine pH

URIC ACID clinical significance lab values?

^^^ Purines & Nucleic Acids (increased)

URIC ACID appearance?

May be colorless; Yellow-brown, yellow to golden-brown

Rhombic (diamond), four-sided flat plates (whetstones), wedges, rosettes

Pleomorphic; often flat, cubic and barrel forms; Lemon sheped

ATYPICAL FORMS - Elongated HEXAGON (mistaken for cystine crystals)

Highly birefringent (distinguish from cystine crystals) & Polychromatic

URIC ACID is usually seen in what conditions?

Seen in patients receiving Chemotherapy, Lesch-nyhan-syndrome, acute febrile conditions, chronic nephritis, urinary (kidhey) stones

If it is in pH >5.7, it transforms into its ionized form called?

URATES

URIC ACID is soluble in what solution?

SOLUBILITY: Alkali (NaOH) and Heat (60℃)

AMORPHOUS URATES (Ca,Mg,Na,K) significance?

No Clinical Significance (seen in pH >5.5)

AMORPHOUS URATES appearance?

• Orange-pink precipitate ("Brick dust"), or yellow brown; SAND-LIKE

• May appear in clumps resembling granular casts and attached to others

• Produce a characteristic pink sediment (accumulation of uroerythrin)

AMORPHOUS URATES Converts to URIC ACID with addition of _______

 glacial acetic acid

AMORPHOUS URATES Converts to AMMONIUM BIURATE with addition of ________________

Ammonium hydroxide

AMORPHOUS URATES can be encountered in ________ but disappear when warmed

REFRIGERATED URINE

AMORPHOUS URATES

SOLUBILITY: Alkali (NaOH) and Heat (60℃) a

Most frequently observed urinary crystal

CALCIUM OXALATE

CALCIUM OXALATE can be found?

Can be found in neutral urine, and even in alkaline pH (rare)

Clumps of CaOx in fresh urine may be related to

CALCULI FORMATION

CaOx Associated in foods with high OXALIC ACID

(tomatoes, asparagus, Vit. C)

CALCIUM OXALATE SOLUBILITY

Dilute HCI, Alkali (NaOH), Nitric Acid (NHO3)

CaloOx Dihydrate form other name?

WeDDelite

Dihydrate form - more common

• Colorless, octahedral envelope or as two pyramids joined at their bases

• Looks like small squares crossed by intersecting diagonal lines

• Bi-pyramidal prisms (8-sided) or dodecahedral (12-sided)

CaloOx monohydrate form other name?

WheWelite

monohydrate form (less common) common shape?

Oval or Dumbbell shaped (sideview); colorless; RESEMBLE RBC

monohydrate atypical form appearance

Elongated hexagons, elongated diamond/rhomboid (spindle)

monohydrate is usually seen in what associated condition and what shape?

• Ethylene Glycol (Antifreeze) Poisoning - MOSTLY HEXAGONAL

• Usually seen in children and pets (Antifreeze is sweet)

Sodium Urates (monosodium) apperance?

• Little clinical significance; spherulite or beachball (rare); Colorless or yellowish; in Infants

• Needle-shaped, slender pencil-like prisms w/ blunt end; cluster looks like pick up sticks

Sodium Urates (Sodium Urates) SOLUBILITY?

Heat (60℃), Alkali (NaOH) slightly soluble in Acetic Acid

Hippuric Acid appearance

Yellow-brown or colorless; elongated prisms or hexagons; so thin that they resemble noodles

Hippuric Acid SOLUBILITY

Alcohol, Ether, water

Calcium Sulfate appearance?

Long, colorless needles or prisms; "Cigarette-butt" shape; identical to Calcium Phosphate

Calcium Sulfate SOLUBILITY?

Acetic Acid

Acid Urates appearance?

• Larger granules and may have spicules similar to ammonium biurate; brown spheres/cluster

• Also resemble leucine & Sulfamethoxazole crystals; turn into Uric acid (add acetic acid)

Acid Urates soluble

Alkali (NaOH) and Heat (60℃)