Approach to polyuria/polydipsia Flashcards
What specific gravity levels suggest hyposthenuria?
1.000-1.008
What levels are isosthenuria?
1.008-1.012
What levels are minimally concentrated urine?
1.013-1.030
What levels are hypersthenuria?
1.030-1.055
What are the main causes of polyuria/polydipsia in dogs?
- diabetes mellitus
- renal failure
- hyperadrenocorticism
- hypercalcaemia
- neoplasia
- pyogenic foci
- hypoadrenocorticism
- pyschogenic polydipsia
What are common causes of polyuria/polydipsia in the cat?
- renal failure
- hyperthyroidism
- diabetes mellitus
- pyogenic foci
- liver failure
- neoplasia
- hypercalcaemia
- diabetes inspidius
what would state a dog is polydipsic?
drinking more than 80ml/kg/day of water
What questions should be asked during a clinical history taking?
behaviour- lethargy, episodic collapse? change in appetite? alopecia? comedomes? vomiting? diarrhoea? discharges? medical history of drugs?urinary obstruction?
What should be checked in a clinical exam?
full exam lymph nodes skin abdominal pain rectal exam thyroid palpation in cats purulent discharges
What are causes of hyposthenuria (SG of 1.001-1.007)?
Loss of concentration gradient- diuresis, hypoadrenocorticism
Loss of ADH or its receptors- primary diabetes insipidus
Antagonism of ADH- hyperadrenocorticism
Excessive water consumption
Kidneys are functioning
What are causes of isothenuria (SG of 1.008-1.012)
Loss of nephrons- renal failure
Normal
What are causes of hypersthenuria (1.030+)?
decreased renal perfusion
A specific gravity greater than what excludes PU/PD?
1.035
A specific gravity range of what excludes diabetes inspidius?
1.008-1.035
What is decreased urea suggestive of?
liver disease
What is increased urea suggestive of?
GI haemorrhage
What is hypokalaemia suggestive of?
renal failure, ketoacidosis
What is hyperphosphataemia suggestive of?
renal failure
What is hypophosphataemia suggestive of?
ketoacidosis
What is hyperglobulinaemia suggestive of?
inflamammatory process
If all diseases are ruled out from haematology what could it be?
cushings disease
Describe the 2 central causes of primary diabetes insipidus
Central (DDAVP responsive)- neoplasia, congenital, trauma, inflammation
Nephrogenic (not DDAVP responsive)- lack of ADH receptors, juvenile nephropathies
Describe water deprivation test method 1
Not common test, used when everything else is ruled out
Need to check kidneys are functioning first
Method 1:
Phase 1- water restriction, 2x maintenance for one day
Phase 2- water deprivation, empty bladder and weigh every 2 hrs, check urea and creatinine every 2 hrs, preserve urine and plasma samples
Requires hospitalisation and close monitoring
Typically lasts around 6 hrs
Describe water deprivation test method 2
Phase 3: DDAVP response 2-4mg DDAVP IV Monitor urine S.G for 2-4 hrs Gradually re-introduce water
