38. Urolithiasis. Disorders of the urination Flashcards

1
Q

Causes of urolithiasis (Crytals in the urine sediment)?

A

Causes Of Urolithiasis

CRYSTALS IN THE URINE SEDIMENT

Microscopic alterations; Some crystals form uroliths whilst others

dissolve

If there are visible stones in the UT, their composition cannot be

diagnosed based on crystals found in the sediment or in the urine.

Cysteine & urate crystals may warrant further workup

Sediment seen during imaging can be organic material – Blood; Pus;

Lipid

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2
Q

Pathogenesis?

A

PATHOGENESIS

Caused by an ↑ of supersaturated urine concentration

§ ↑ Protein & mineral-containing feed; ↑ Bacterial

production of NH4 of PO4 ions; ↓ Water intake; ↓ Tubular

resorption

§ Nidus (crystallisation centre) formation – May be organic

or inorganic

§ Urine stasis in the bladder

§ Ø Crystallisation inhibitors (Citrates; Glycosaminoglycans;

Pyrophosphates)

§ Always secondary to other diseases or problems: UTI;

Hepatopathy; Metabolic disease; Genetic disease

Occurrence: 90-95% in the urinary bladder

§ Struvite

§ Calcium oxalate

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3
Q

Clinical signs?

A

CLINICAL SIGNS

Dependent on the number, types & location of stones

§ Urinary bladder: Signs of cystitis;

§ Male dogs: Urethral obstruction; Postrenal uraemia; AKI

§ Ureter: Ø CSx; Pain; Haematuria; Hydronephrosis

§ Kidney: Ø CSx; Haematuria; Pyelonephritis; CRF in

bilateral cases

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4
Q

Struvite?

A

STRUVITE

40-60% of all uroliths; Alkaline/neutral urine

Predisposed: Females > Males; Dachshund; Poodle; Mini-schnauzer

Dog

Usually caused by UTI

Urease (from Staphylococcus/Proteus spp.) → Alkaline urine →

↑ NH4 concentration

Cat: Cases are usually sterile

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5
Q

Calcium oxolate?

A

CALCIUM OXALATE

~15-50% of all uroliths; ↑ in frequency of cases; Acidic urine

Acidic urine: Hypercalciuria;

↓ Urine citrate concentration (which acts as a crystallisation

inhibitor); ↑ Oxalate

Predisposed: Poodle; Mini-schnauzer; Yorkshire terrier

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6
Q

Urate?

A

URATE

Ammonium acid urate

§ ↑ Urate in urine: Dalmatian; English bulldog

§ ↑ Ammonium & urate in urine: Dogs with hepatic

insufficiency (PSS/Cirrhosis); UTI

§ ↓ Glycosaminoglycans in the urine

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7
Q

Cysteine?

A

CYSTEINE

Cystinuria: Inherited disorder of renal tubular transport + acidic urine Predisposed: Males; Middle aged dogs; Siamese cats

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8
Q

Diagnosis of urolithiasis?

A

Diagnosis of Urolithiasis

§ Radiography (contrast)

§ US; Stone analysis

§ Bacterial culture

§ Re-evaluation of patients

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9
Q

Treatment of urolithiasis?

A

Treatment Of Urolithiasis

Emergency urethral obstruction:

§ Catheterisation

§ Decompression of bladder

§ Treatment of AKI & its consequences

§ Surgical removal

§ Urohydropropulsion

§ Treat UTI

Diuresis induction

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10
Q

Treatment of struvite, calcium oxolate, urate and cysteine?

A

STRUVITE

§ Diet: ↓ Protein, Ca, Mg & P; ↑ Dietary salt for dissolution

§ If UTI is confirmed → Abx; Acidifier: NH4Cl/Methionine

§ Cats require life-long dietary prevention

CALCIUM OXALATE

§ Surgery is required (Ø Medical management available)

§ Diet: ↓ Protein; ↓ Nucleic acids; ↑ Dietary salt for

dissolution

§ Potassium citrate; Avoid excess alkalisation

URATE

Ø Associated with hepatic insufficiency

§ Diet: ↓ Purine; ↓ Nucleic acids; ↓ Added salts

§ Urine alkalisation; Xanthine oxidase; UTI treatment

CYSTEINE

§ Diet: ↓ Protein; ↓ Sodium (salt); Methionine for dissolution

& prevention

§ Urine alkalisation

§ Thiol-containing drugs: D-penicillamine/MGP/N-glycine

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