Post on 13-Dec-2015
Denmark September 2014
Klinik für Kleintiere
(Innere Medizin)
Justus-Liebig Universität Giessen
POLYURIA / POLYDIPSIA
Reto Neiger
Denmark September 2014
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
Denmark September 2014
Specific gravity (SG) vs Osmolality (Osmo)
1000 1008 1012 1035
Iso-sthenuric
Hypo-
280 320
SG
Osmo
Denmark September 20144
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
Denmark September 2014
Med
ulla
C
orte
x afferent
efferent
Glomerulus
Prox. Tub
Loop of Henle
Dist. Tub
Collectingduct
Denmark September 2014
Med
ulla
C
orte
x afferent
efferent
Glomerulus
Prox. Tub
Loop of Henle
Dist. Tub
Collectingduct
300
300
300
NaClH2O
urea300
Denmark September 2014
Med
ulla
C
orte
x afferent
efferent
Glomerulus
Prox. Tub
Loop of Henle
Dist. Tub
Collectingduct
300
300
300
NaClH2O
urea300
Denmark September 2014
Inte
rsti
tium
Des
cend
ing
thin
lim
b
Asc
endi
ng th
ick
lim
b
H2O
H2O
H2O
H2ONaCl
NaCl
NaCl
NaCl
Denmark September 2014
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
300
Denmark September 2014
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
Denmark September 2014
300
300
300
300
400
400
400
400
200
200
200
200
400
400
400
400
Denmark September 2014
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
Denmark September 2014
300
300
350
350
350
350
500
500
200
200
300
300
300
300
500
500
Denmark September 2014
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
Denmark September 2014
300
325
325
425
425
425
425
600
125
225
225
225
225
400
400
600
Denmark September 2014
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
Denmark September 2014
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
Denmark September 2014
Countercurrent mechanism
Denmark September 2014
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
Denmark September 2014
Collecting duct cellsLumen
H2 O
H2O
H2O
H 2O
Denmark September 2014
Lumen
Collecting duct cell
TJTJ = Tight JunctionsWater tight
H2O
H 2O
Denmark September 2014
Lumen
H2O
H 2O
V2-Receptor
AVP
AVP
Collecting duct cell
G-Protein
ATP
cAMP
AVP= Arginin-Vasopressin (ADH
PKA
PKA= Proteinkinase A
Denmark September 2014
Lumen
H2O
H 2O
V2-Receptor
AVP
Collecting duct cell
G-Protein
ATP
cAMP
PKA
AQP2
AQP2 = Aquaporinkanäle
Denmark September 2014
Lumen
H2O
H 2O
V2-Receptor
AVP
Collecting duct cell300
900
1200
Inte
rstit
ium
H2O
Denmark September 2014
Urine Osmolality
Stockham and Scott: Fundamentals of Veterinary Clinical Pathology 2008
Denmark September 2014
Med
ulla
C
orte
x
Differential diagnosis
1. Osmotic Diuresis
Denmark September 2014
Differential diagnosis1. Osmotic Diuresis
Normoglycaemia
GlucoseFreely filtered
Glucose
No Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
100%
Denmark September 2014
Differential diagnosis1. Osmotic Diuresis
Hyperglycaemia(> renal threshhold)
GlucoseFreely filtered
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
Not
100
%
Glucose
Glucose
Denmark September 2014
Differential diagnosis
1. Osmotic Diuresis Diabetes mellitus Renal glucosuria
Hyperglycaemia(> renal threshhold)
GlucoseFreely filtered
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
Glucose
Not
100
%
Glucose
Glucose
Denmark September 2014
Med
ulla
C
orte
x
Differential diagnosis
2. Lack of AVP
Denmark September 2014
Med
ulla
C
orte
x Differential diagnosis
2. Lack of AVP Diabetes insipidus
Denmark September 2014
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
Denmark September 2014
Lumen
H2O
H 2O
AVP
Collecting duct cellCentral D. Inspipidus
Renal D. Inspipidus
Denmark September 2014
Med
ulla
C
orte
x Differential diagnosis
2. Lack of AVP Diabetes insipidus
Secondary renal D.i. Hypercalcaemia Hypercortisolism
PyometraPyelonephritisHypokalaemia
Hyperthyroidism Acromegaly
Denmark September 2014
Med
ulla
C
orte
x Differential diagnosis
3. Chronic kidneyDisease (CKD)
Denmark September 2014
CKD
33%25%
Loss of concentrating
ability(Isosthenuria)
azotaemia
Compensation
Total kidney mass
100%
Creatinine Blind
Window
Denmark September 2014
Med
ulla
C
orte
x Differential diagnosis
Liver diseaseHypoadrenocorticism Marked hyponatraemiaChronic PU/PD
4. Medullary Washout
Denmark September 2014
Med
ulla
C
orte
x Differential diagnosis
5. Primary Polydypsia
Denmark September 2014
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
Denmark September 2014
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
Denmark September 2014
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
Denmark September 2014
2. Inspect minimum data base
• Urine specific gravity• Glucosuria• Bacteriuria / pyuria• Azotaemia• Hypercalcaemia• Electrolyte changes• Values pointing towards liver disease• Values pointing towards hypercortisolaemia
Denmark September 2014
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
Denmark September 2014
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
Denmark September 2014
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
Denmark September 2014
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.
Denmark September 2014
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