Approach to Common Complaints

What is normal urine output?

1-2mL/kg/hr

What is polyuria?

Urine output >50mL/kg/day or >2mL/kg/hr

What is polydipsia in a dog?

Water intake >90-100 mL/kg/day

What is polydipsia in a cat?

>50mL/kg/day

What are some environmental or dietary causes of increased water intake?

High temperature

Exercise

Feeding more

Higher protein

Salt content

Higher digestibility

What is the pathophysiology of PU/PD?

Animal is drinking too much and animal is urinating too much

What is it called when the animal is drinking too much, but the kidneys can concentrate urine?

Primary polydipsia

What is it called if the animal is urinating too much because of inappropriate urine concentrating ability?

Primary polyuria

What are causes of primary polydipsia?

Psychogenic

Hepatic encephalopathy

Hyperthyroidism

Hypothalamic lesion

Drugs

What happens during primary polydipsia?

Behavioral problem or form of cerebro-cortical dysfunction

Can be an intra-cranial or extra-cranial abnormality

What 3 things are needed to concentrate urine?

Presence of ADH

Tubules that are responsive to ADH

Hypertonic medullary interstitium

What is happening with primary polyuria?

Reduced nephron number or function

Problem with ADH

Altered osmolarity of the glomerular filtrate

Why does a reduced nephron number/function cause primary polyuria?

It creates a concentrated medullary interstitium which increases concentration gradient and therefore concentrated urien

What are causes of reduced nephron number/function?

Structural renal tubule damage

CKD

Pyelonephritis

Bilateral renal neoplasia

What can cause absent or deficient ADH?

Central diabetes insipidus

What can cause impairment of ADH function?

Nephrogenic diabetes insipidus

Describe primary nephrogenic diabetes insipidus?

Hereditary disorder of ADH receptors

Seen in YOUNG ANIMALS

What causes secondary nephrogenic diabetes insipidus?

Conditions that interefere with funciton of ADH

What electrolyte disturbances can cause secondary nephrogenic diabetes insipidus?

Hypokalemia

Hyponatremia

Hypercalcemia

What endocrine disorders can cause secondary nephrogenic diabetes insipidus?

Hyperaldosteronism

Hyperadrenocorticism

Hypoadrencorticism

What is the only endocrine disorder that CANNOT cause secondary nephrogenic diabetes insipidus?

Hypothyroidism

What can cause secondary nephrogenic diabetes insipidus?

Liver dz

Decreased urea

Infectious

Electrolyte disturbances

Endocrine

What infections can cause secondary nephrogenic diabetes insipidus?

Endotoxemia

Leptospirosis

Pyometra - E. coli

Why does altered osmolarity of glomerular filtrate cause primary polyuria

Tubular filtrate has a higher amount of osmotically active particles than the interstitium

What are causes of an altered osmolarity of glomerular filtrate?

Diabetes mellitus

High salt or protein diet

Post-obstructive diuresis

Drugs

Renal medullary washout

What are the steps to work up PU/PD?

1. Make sure it is present

2. Signalment, history, PE

3. CBC, Chem, UA

4. Urine culture and specific testing

5. DDAVP trial

What is the biggest challenge to working up a PU/PD case?

Making sure it is actually present

What is urinanry incontinence?

The involuntary escape of urine during the storage phase of the micturition cycle

What is pollakiruia?

Abnormally frequent urination of small amounts

What are causes of pollakiuria?

UTI, urolithiasis, FIC, neoplasia

What is stranguria?

Slow and painful urination with spasmodic contraction of the bladder and urethra

What are causes of stranguria?

UTI, urolithiasis, FIC, neoplasia

How do you work up urinary incontinence, pollakiuria, and stranguria?

Physical and neuro exam

Urinalysis and culture

CBC, chem

Abdominal radiographs and ultrasound

Cystoscopy

What are the storage disorders?

USMI

Ectopic ureter

Detrusor instability/overactive bladder

LMN bladder

What are the voiding disorders?

Detrusor atony

FOO

MOO

UMN bladder

What can cause hematuria?

Bleeding disorder

Urolithiasis

UTI

Neoplasia

Trauma

Benign mass

What are causes of hemoglobinuria?

Intravascular hemolysis, either immune-mediated or not

What are causes of myoglobinuria?

Muscle damage/necrosis

Thrombosis

What are causes of bilirubinuria?

Physiologic

Pre-hepatic

Hepatic

Post hepatic

How can you determine if PU/PD is present based on USG?

If it is above 1.030 or 1.035 in dogs or cats then it is unlikely PU/PD

What is the best way to confirm PU/PD?

Have owners measure water intake and urine output

How are most causes of PU/PD determined?

CBC, Chem, UA

When would you do a DDAVP trial?

When you ruled out every other cause of PU/PD except for central and nephrogenic diabetes insipidus

How do you do a DDAVP trial?

Give DDAVP and if c/s like PD and USG improve then it is central DI

What is DDAVP?

Synthetic ADH

Why do we not do a water deprivation test?

Is it not safe and can be misdiagnosed often

What is the first step if there is pollakiuria/stranguria as the presenting complaint?

Palpate bladder

Large bladder with pollakiuria have what ddx?

UTI, FIC, urogenital mass, urolithiasis, neurogenic bladder dysfunction

You have a patient come in with pollakiuria, a large bladder, with an active urine sediment and a positive culture what is your diagnosis?

UTI or prostatitis

You have a patient come in with pollakiuria, a large bladder, with an active urine sediment but a negative culture what is your diagnosis?

FIC

A patient comes in with pollakiuria, small bladder, frequent large volume of urine what do you suspect?

It is PU/PD and might not be pollakiuria

A patient comes in with pollakiuria, small bladder, frequent small volume of urine what do you suspect?

Cystitis, FIC, or detrusor instability

A patient comes in with pollakiuria/stranguria, with a small bladder, but normal urination what do you suspect?

Recheck clinical signs

A patient comes in with red, brown, or black urine. A heme patch is positive and a urine sediment exam shows RBCs what is your dx?

Hematuria

A patient comes in with red, brown, or black urine. A heme patch is positive and a urine sediment exam shows no RBCs. The plasma is pink what is your dx?

Hemoglobinuria

A patient comes in with red, brown, or black urine. A heme patch is positive and a urine sediment exam shows no RBCs. The plasma is CLEAR what is your dx?

Myoglobinuria

A patient comes in with red, brown, or black urine. A heme patch is positive and a urine sediment exam shows no RBCs. What is the next step?

Evaulate plasma color

A patient comes in with red, brown, or black urine. The heme patch is negative what is the next step?

Bilirubin patch

A patient comes in with red, brown, or black urine. The heme patch is negative. The bilirubin patch is positive what is the dx?

Bilirubinuria

A patient comes in with red, brown, or black urine. The heme patch is negative. The bilirubin patch is negative what is the dx?

Other pigment due to drugs, porphyrins, or dyes