Denmark September 2014 Klinik für Kleintiere (Innere Medizin) Justus-Liebig Universität Giessen...

Denmark September 2014

Klinik für Kleintiere

(Innere Medizin)

Justus-Liebig Universität Giessen

POLYURIA / POLYDIPSIA

Reto Neiger


Definition POLYDIPSIA (PD)

Increased thirst: mostly due to polyuria

Rarely a primary problem- psychogenic- neurological - hyperrenism

POLYURIA (PU)

Increased production of urine (low SG)

Due to disorder of water homeostasis with abnormal cellular and plasma osmolality


Specific gravity (SG) vs Osmolality (Osmo)

1000 1008 1012 1035

Iso-sthenuric

Hypo-

280 320

SG

Osmo


Mostly very good correlation• increasing osmolality increasing USG

EXEPTIONS• high [Proteins]

1 g/dL 0.003-0.005• high [Glucose]

1 g/dL 0.004-0.005

Osmolality vs specific gravity

1.000

1.005

1.010

1.015

1.020

1.025

0 200 400 600 800 1000

Urine Osmolality (mosmol/kg)

US

Gre

f


Med

ulla

C

orte

x afferent

efferent

Glomerulus

Prox. Tub

Loop of Henle

Dist. Tub

Collectingduct


Med

ulla

C

orte

x afferent

efferent

Glomerulus

Prox. Tub

Loop of Henle

Dist. Tub

Collectingduct

300

300

300

NaClH2O

urea300


Inte

rsti

tium

Des

cend

ing

thin

lim

b

Asc

endi

ng th

ick

lim

b

H2O

H2O

H2O

H2ONaCl

NaCl

NaCl

NaCl


300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300

300


400

400

400

400

400

400

400

400

200

200

200

200

200

200

200

200

Equilibrium

400

400

400

400

400

400

400

400


300

300

300

300

400

400

400

400

200

200

200

200

400

400

400

400


350

350

350

350

500

500

500

500

150

150

150

150

300

300

300

300

350

350

350

350

500

500

500

500

Equilibrium


300

300

350

350

350

350

500

500

200

200

300

300

300

300

500

500


325

325

425

425

425

425

600

600

125

125

225

225

225

225

400

400

325

325

425

425

425

425

600

600

Equilibrium


300

325

325

425

425

425

425

600

125

225

225

225

225

400

400

600


312

375

475

425

425

513

513

700

125

125

225

225

225

225

400

400

312

375

475

425

425

513

513

700

Equilibrium


Med

ulla

C

orte

x afferent

efferent

Glomerulus

Prox. Tub

Loop of Henle

Dist. Tub

Collectingduct

300

300

300

NaClH2O

urea300300

900

1200

900

80

200

Inte

rstit

ium

300

900

1200


Countercurrent mechanism


Med

ulla

C

orte

x afferent

efferent

Glomerulus

Prox. Tub

Loop of Henle

Dist. Tub

Collectingduct

300

300

300

NaClH2O

urea300300

900

1200

900

80

200

Inte

rstit

ium

300

900

1200


Collecting duct cellsLumen

H2 O

H2O

H2O

H 2O


Lumen

Collecting duct cell

TJTJ = Tight JunctionsWater tight

H2O

H 2O


Lumen

H2O

H 2O

V2-Receptor

AVP

AVP


G-Protein

ATP

cAMP

AVP= Arginin-Vasopressin (ADH

PKA

PKA= Proteinkinase A


Lumen

H2O

H 2O

V2-Receptor

AVP


G-Protein

ATP

cAMP

PKA

AQP2

AQP2 = Aquaporinkanäle


Lumen

H2O

H 2O

V2-Receptor

AVP

Collecting duct cell300

900

1200

Inte

rstit

ium

H2O


Urine Osmolality

Stockham and Scott: Fundamentals of Veterinary Clinical Pathology 2008


Med

ulla

C

orte

x

Differential diagnosis

1. Osmotic Diuresis


Differential diagnosis1. Osmotic Diuresis

Normoglycaemia

GlucoseFreely filtered

Glucose

No Glucose

Glucose

Glucose

Glucose

Glucose

Glucose

100%


Differential diagnosis1. Osmotic Diuresis

Hyperglycaemia(> renal threshhold)


Glucose

Glucose

Glucose

Glucose

Glucose

Glucose

Glucose

Not

100

%

Glucose

Glucose



1. Osmotic Diuresis Diabetes mellitus Renal glucosuria

Hyperglycaemia(> renal threshhold)


Glucose

Glucose

Glucose

Glucose

Glucose

Glucose

Glucose

Not

100

%

Glucose

Glucose


Med

ulla

C

orte

x


2. Lack of AVP


Med

ulla

C

orte

x Differential diagnosis

2. Lack of AVP Diabetes insipidus


Diabetes insipidus• Central diabetes insipidus• Congenital

rarely in dogs and cats• Acquired

rarely in dogs and cats

• Renal diabetes insipidus• Congenital

very rare in dogs and cats

• Acquired very common in dogs and also in cats


Lumen

H2O

H 2O

AVP

Collecting duct cellCentral D. Inspipidus

Renal D. Inspipidus


Med

ulla

C

orte


2. Lack of AVP Diabetes insipidus

Secondary renal D.i. Hypercalcaemia Hypercortisolism

PyometraPyelonephritisHypokalaemia

Hyperthyroidism Acromegaly


Med

ulla

C

orte


3. Chronic kidneyDisease (CKD)


CKD

33%25%

Loss of concentrating

ability(Isosthenuria)

azotaemia

Compensation

Total kidney mass

100%

Creatinine Blind

Window


Med

ulla

C

orte


Liver diseaseHypoadrenocorticism Marked hyponatraemiaChronic PU/PD

4. Medullary Washout


Med

ulla

C

orte


5. Primary Polydypsia


Plan for animal with PU/PD

1. Confirmation that problem exists

2. Inspection of data base for clues

3. Performance of special diagnostic tests

4. Performing urine concentrating tests


1. Confirmation of problem

Differentiate PU from stranguria, pollakiuria, dysuria

Measure water intake at home Analyse urine specific gravity

Species H20 intake Urine output Urine SG

Dog < 100 ml/kg/d 20-45 ml/kg/d > 1030

Cat < 75 ml/kg/d 20-40 ml/kg/d > 1035


2. History and physical examinationIntact female: r/o pyometraLymphadenopathy: r/o hypercalcemiaWeigh loss, tachycardia, restless:

r/o hyperthyroidism, diabetes mellitusAlopecia, potbelly, muscle weakness, hepatomegaly: r/o

hypercortisolaemiaDrugs: r/o steroids, diuretics, primidone, salt

supplementation


2. Inspect minimum data base

• Urine specific gravity• Glucosuria• Bacteriuria / pyuria• Azotaemia• Hypercalcaemia• Electrolyte changes• Values pointing towards liver disease• Values pointing towards hypercortisolaemia


3. Special diagnostic testsLiver function tests

Bile acid stimulation test, ammonia tolerance testTests for hypercortisolaemia

Low Dose Dexamethasone Suppression testACTH-Stimulation testCortisol:creatinine-ratio in urine

CalciumMeasure ionised calcium

GFR study Creatinine clearence


4. Water deprevation test• Contraindication:

• Renal disease (Azotemia)• Dehydration

• Rule out all other causes of PU/PD• Equipment:

• Refractometer (for urine specific gravity)• Exact scale (to measure weight of animal)• Catheter to empty bladder• ADH for i.m. injection


Protocol

• Reduce water intake slowly to 75 ml/kg/d• Remove water and food• Empty bladder and measure spec. gravity (SG) of urine

• Obtain exact weight of dog (kg) and write down• Empty bladder q 1-2 h; measure SG and kg every time

• Stop if >5% dehydrated (or SG >1030)• Give ADH (2-5 U i.m.) and continue 1-2 h


Water deprivation test

0 1 2 3 4 5 6 7 81000

1010

1020

1030

1040

1050Normal

Psychogenic poly-dipsia

Complete central DI

Partial central DI

Nephrogenic DI

US

G

± Hours ADH-inj.


Urine specific gravity > 1035

Glucosuria

Pyuria/Bacteriuria

Azotemia

Hypercalzemia

Neutrophilia

Electrolyte change

ACTH-ST / LDDST

Liver function test

Water deprivation test

positive

positive

positive

positive

positive

positive

positive

D.m.,1°Glucosuria, Drugs, Stress

Pyelonephritis, Pyometra, Prostatitis

CKD, Addison, Hyperthyroid, …

Malignancy(LSA), Hyperparathyroid.Addison, Granulomatous, …

Pyometra, Cushing, Pyelonephritis

Addison, Hypokaliemia, …

Hypercortisolism

Hepatopathy

1°Polydipsia Central DI Renal DI

No PU/PD

positive

Denmark September 2014 Klinik für Kleintiere (Innere Medizin) Justus-Liebig Universität Giessen...

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