Urates: Ammonium and amorphous urate crystalluria

Ammonia urate (also called ammonia biurate) crytals are often detected in slightly acidic, neutral or alkaline urine. Usually they’re brown or yellowish brown and may develop small spheres or sphere-like objects with long irregular spikes (so called Datura form) (Fig. 43-51).

Sodium, potassium, magnesium- and calcium urate salt may precipitate in acidic urine in amorphous form (so called amorphous urates). They may resemble to amorphous phosphates (Fig. 49) but they dissolve themselves in an alkaline environment. When the amorphous crystals are growing (Fig. 47-51) they evolve a characteristic yellow or yellowish brown colour.

Sodium urate may also precipitate as colourless or yellow needles or as slim prisms which occur in bundles or heaps (Fig. 52-56).

Ammonium urate- and amorphous urate crystals aren’t dissolving in acetic acid but the addition from 10%ual acetic acid to the urine sediment which contain these crystals often leads to the appearance of uric acid- and sometimes to sodium urate-crystals (for further details see discussion about uric acid crystalluria). The addition of acetic acid to amorphous phosphate crystals leads to a quick dissolving whereas they withstand in alkaline urine sediment.

Interpretation
Ammonium urate and amorphous urates may occur in clinical inconspicuous dogs and cats but not very often. They’re often being observed in dogs with anomaly portal veins with or without simultaneously ammonium urate calculus. They are also being found in Dalmatian dogs, English Bulldogs and other dogs and cats with urinary stones of ammonium urate which are being caused by other diseases than portal veins anomaly.

Fig. 43)

Microphotographic picture from ammonium urate crystals (Datura form) in the urine sediment from a three-year-old male English Bulldog with bladder calculus of ammonium urate.

Fig. 44)

Microphotographic picture from a Daluta-like formed ammonium urate crystal in the urine sediment from a seven-month-old Yorkshire-Terriers with portal veins anomaly.

Fig. 45)

Scanning electron microscope picture from a Daluta-like shaped ammonium urate in the urine sediment from the dog from Fig. 44.

Fig. 46)

Microphotographic picture from ammonium urate crystals in the urine sediment from a one-year-old female Persian cat with portal veins anomaly.

Fig. 47)

Microphotographic picture from yellowish brown amorphous ammonium urate crystals and transparent magnesium ammonium phosphate crystals in the urine sediment from a three-year-old male English Bulldog with bladder calculus of ammonium urate.

Fig. 48)

Scanning electron microscope picture from an amorphous ammonium urate crystal in the urine sediment from the dog from Fig. 43 and 47.

Fig. 49)
Microphotographic picture from amorphous ammonium urate crystals in the urine sediment from a seven-year-old Alaska Malamute with bladder calculus of ammonium urate.

 

Fig. 50)

Scanning electron microscope picture from amorphous ammonium urate crystals besides uric acid crystals are lying in acidified urine sediment from the dog from Fig. 49.

Fig. 51)

Microphotographic picture from amorphous ammonium urate crystals in urine sediment from the dog from Fig. 44.

Fig. 52)

Microphotographic picture from sodium urate crystals in the urine sediment from the dog from Fig. 49.

Fig. 53)

Microphotographic picture from yellow brown coloured sodium urate crystals, magnesium ammonium phosphate crystals and calcium oxalate dihydrate crystals in the urine sediment from a dog.

Fig. 54)

Microphotographic picture from ammonium urate crystals in the urine sediment from the dog from Fig. 43)

Fig. 55)

Microphotographic picture from a sodium urate crystal in the urine sediment from the dog from Fig. 43 and 54 after addition of 10%ual acetic acid.

Fig.56)

Scanning electron microscope picture from a sodium urate crystals in acidified urine sediment from the dog from Fig. 43, 54 and 55. Notice the small diamond shaped uric acid crystal.