Crystalluria signifies that the urine is supersaturated with the compounds that comprise the crystals, e.g. ammonium, magnesium and phosphate for struvite. Crystals will be seen within the urine of clinically wholesome animals or in animals with no proof of urinary illness (corresponding to obstruction and/or urolithiasis). Nevertheless, some crystals will be pathologically related in sure circumstances (see instance of ammonium biurate beneath). Observe that crystals might not kind in all urine supersaturated with these compounds. A variety of in vivo and in vitro elements affect the categories and numbers of urinary crystals in a given pattern as indicated within the desk beneath.
Crystals are subjectively quantified in urine as few, reasonable and lots of. For crystals which are giant, e.g. calcium carbonate and struvite, this evaluation is made out of low energy (10x goal). For smaller crystals (e.g. amorphous, calcium oxalate dihydrate), the excessive energy (40x goal) is used. Further info on some particular crystals seen in urine are given beneath.
Struvite
Struvite crystals (magnesium ammonium phosphate, triple phosphate) often seem as colorless, three-dimensional, prism-like crystals (“coffin lids”). Often, they as an alternative resemble (vaguely) an old style double-edged razor blade (decrease body). They’re often giant and will be readily noticed at low magnification (nevertheless, affirmation of crystal id ought to all the time be carried out below excessive magnification). Struvite crystals are the commonest sort in urine from canines and cats. They’re usually seen in urine from clinically regular people. Although they are often present in urine of any pH, their formation is favored in impartial to alkaline urine. Urinary tract an infection with urease-positive micro organism can promote struvite crystalluria (and urolithiasis) by elevating urine pH and rising free ammonia.
Bilirubin
Bilirubin crystals kind from conjugated bilirubin (water soluble) and are needle-like to granular crystals which are yellow in shade. They have a tendency to precipitate onto different shaped components within the urine. Within the prime image, fantastic needle-like crystals have shaped on an underlying cell. That is the commonest look of bilirubin crystals. Within the decrease two footage, cylindrical bilirubin crystals have shaped in affiliation with droplets of fats, leading to a “flashlight” look. This way is much less generally seen. They’re often small crystals which are often solely noticed at excessive magnification (until there are giant aggregates of crystals). Bilirubin crystals are seen mostly in canine urine, particularly in extremely concentrated specimens. They’re much less widespread in urine of different species. In canines, they usually are of no medical significance (wholesome canines can have low, however detectable, bilirubin ranges in urine). Bilirubin crystals (or a constructive chemical response on the urine dipstick) in feline, equine, bovine, or camelid urine is an irregular discovering and the animal ought to be investigated for an underlying cholestatic course of.
Calcium carbonate
Calcium carbonate crystals are variably sized crystals that regularly seem as giant spheroids with radial striations. They may also be seen as smaller crystals with spherical to ovoid shapes. they’re colorless to yellow-brown and might impart a brownish tinge to the urine, once they happen in excessive numbers. They’re often giant crystals and will be readily noticed at low magnification (nevertheless, affirmation of crystal id ought to all the time be carried out below excessive magnification and smaller variants of calcium carbonate could also be missed if solely low magnification is used). These crystals are widespread within the urine of regular horses, rabbits, guinea pigs and goats. They haven’t been noticed in canine or feline urine.
“Amorphous” crystals – “calcium oxalate monohydrate crystals”
“Amorphous” crystals seem as aggregates of finely granular materials with none defining form on the mild microscopic degree. They are often comprised of urates, phosphates or xanthine. They’re often small crystals which are often solely noticed at excessive magnification (until there are giant quantities of them), i.e. they mimic micro organism.
Amorphous urates (Na, Ok, Mg, or Ca salts) are inclined to kind in acidic urine and should have a yellow or yellow-brown shade. Amorphous phosphates are comparable usually look, however are inclined to kind in alkaline urine and lack shade. Xanthine crystals are often within the type of “amorphous” crystals, nevertheless some can resemble ammonium biurate (Hooijberg et al, www.escvp.org case). These crystals happen in Dalmations on allopurinol remedy for urate urolithiasis. Typically, no particular medical interpretation will be made primarily based on the discovering of amorphous crystals. Small amorphous crystals will be confused with bacterial cocci in some circumstances, however will be distinguished by gram-staining. Degenerating crystals or cells also can resemble “amorphous” crystals.
Calcium oxalate dihydrate
Calcium oxalate dihydrate crystals usually are colorless squares whose corners are linked by intersecting strains (resembling an envelope). They will happen in urine of any pH. The crystals fluctuate in measurement from fairly giant (will be noticed below low magnification) to very small (require huge magnification to visualise). In some circumstances, giant numbers of tiny oxalates might seem as amorphous until examined at excessive magnification. These crystals are sometimes seen in regular urine from home animals and may also be an artifact of storage (they will develop in saved urine), emphasizing the necessity to carry out a urinalysis on recent urine samples.
Urolithiasis on account of calcium oxalate has been reported in each canines and cats. In some circumstances, they happen secondary to irregular calcium (elevated) excretion on account of problems of calcium metabolism (e.g. hyperparathyroidism). Miniature Schnauzers are predisposed to calcium oxalate urolithiasis, regardless of no abnormalities in urinary calcium excretion. Calcium oxalate dihydrate crystals may also be seen in circumstances of ethylene glycol intoxication, though the picket-shaped type of calcium oxalate monohydrate are extra particular for this toxicosis (see beneath) and never seen within the urine from wholesome animals. If seen in giant numbers within the urine of a canine or cat with acute renal failure and different applicable medical indicators, consideration ought to be given to this analysis.
Calcium oxalate monohydrate
Calcium oxalate monohydrate crystals fluctuate in measurement and should have a spindle, oval, or dumb-bell form (for examples, see the 2 unlabeled crystals within the decrease left nook of the picture beneath proper). These types of calcium oxalate monohydrate point out supersaturation of the urine with calcium and oxalate and, together with calcium oxalate dihydrate crystals (“square envelopes”), will be seen within the urine of animals that haven’t any urologic issues or these affected by oxalate urolithiasis, hypercalciuric or hyperoxaluric problems, or hardly ever ethylene glycol toxicosis. They’re rare within the urine of regular canines and cats however will be seen within the urine from wholesome horses. These will be seen at low magnification, nevertheless low numbers might solely be recognized at excessive magnification (and crystal id ought to be verified below excessive magnification, significantly as a result of pathologic relevance of the “picket fence” type of these crystals).
A selected type of calcium oxalate monohydrate are flat, elongated, six-sided crystals (“picket fences”) that are the bigger crystals within the picture above (which represents urine from a canine with ethylene glycol toxicosis). The arrow within the picture signifies a “daughter” crystal forming on the face of a bigger underlying crystal. These “picket fence” types of calcium oxalate monohydrate are regularly related to ethylene glycol intoxication in canines and cats, however aren’t all the time noticed within the urine of affected animals (i.e. not 100% delicate). They may also be seen within the urine of animals with hypercalciuria from different causes, e.g. paraneoplastic hypercalcemia with lymphoma. One other uncommon type of calcium oxalate monohydrate are the “hempseed” variant or “orzo” (as within the pasta form). The left picture above is from the urine of a canine with many of those crystals. The canine didn’t have ethylene glycol poisoning and the crystals are assumed to be secondary to supersaturation of the urine with calcium and oxalates, which precipitated within the acidic urine.