Microscopic Analysis of Urine
Faculty of Medicine, Masaryk University
RNDr. Miroslava Beňovská, Ph.D., Mgr. Ondřej Wiewiorka, MUDr. Jana Tůmová

Crystals

The presence of crystals and amorphous microcrystalline deposits in urine is not considered a significant clinical finding. However, both parameters are determined and their amount is evaluated.

Crystals have various crystalline structure and they occur in many forms. The pH of urine is important factor for their formation and structure, although it is sometimes difficult to distinguish them even then. In that case, the elements could be classified only as crystals – without further specification.

The most frequent crystals in urine are: oxalate and uric acid (in acidic urine) or phosphate (in alkaline urine). Rarely found crystals in urine: bilirubin, cysteine, leucine, tyrosine or drug. We distinguish two types of amorphous microcrystals – amorphous urates in acidic urine and amorphous phosphates in alkaline urine.

Oxalates

Stained sediment

Native sediment

Pictures from FUS-2000 analyzer (DIRUI)

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Uric acid

Various forms of crystals of uric acid

Stained sediment

Native sediment

Pictures from FUS-2000 analyzer (DIRUI)

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Ammonium urate

Stained sediment

Native sediment

Pictures from FUS-2000 analyzer (DIRUI)

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Triple phosphate

Ammonium magnesium phosphate crystals (Triple phosphate).

Stained sediment

Native sediment

Pictures from FUS-2000 analyzer (DIRUI)

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Calcium phosphate

These crystals can be differentiated from uric acid crystals by polarization microscopy. Unlike uric acid, calcium phosphate doesn't turn polarized light.

Stained sediment

Native sediment

Pictures from FUS-2000 analyzer (DIRUI)

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Bilirubin

Stained sediment

Native sediment

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Cystine

Stained sediment

Native sediment

Pictures from FUS-2000 analyzer (DIRUI)

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Amorphous microcrystals

Stained sediment

Native sediment

Pictures from FUS-2000 analyzer (DIRUI)