Lecture 1 - Renal Flashcards
What is the function of the proximal tubule?
Maintains the volume + balanced composition of extracellular fluid
What is the function of the RAAS system in the distal tubule and collecting tubule?
Controls local glomerular harm-dynamics, sodium re-absorption and systemic blood pressure
What is the function of ADH within the collecting tubule?
ADH promotes water (and urea) in collecting duct. PTH promotes Ca and Mg reabsorption
What stimulates increased ADH secretion?
Changes in certain plasma solutes (sodium, glucose) and changes in blood volume or pressure
How does ADH decrease water loss occurring from the kidney?
- Increases permeability of the distal and collecting tubules from kidney 2. Medullary hypertonicity –> draws water from renal tubules into medullary interstitial and vasculature by osmotic gradient
What is polydipsia?
Consumption of larger than normal amount of water per day
What is considered to be polydipsia in dogs and cats?
Dog: 100 mL/kg/day Cat: 50 mL/kg/day
What is polyuria?
Excretion of a larger than normal volume or urine per day.
What volume suggests polyuria in dogs and cats?
Cat and dog - production of greater than 50 mL/kg of urine per day
What are the differentials that should be considered with polydipsia?
- Physchogenic polydipsea 2. Endocrine disorders - hyperadrenocorticism in dogs and hyperthyroidism in cats 3. Hepatic encephalopathy 4. Rare hypothalamic (thirst centre) lesion 5. Drug therapy e.g. phenobarbitone
What are the three major pathophysiologic processes causing polyuria?
- Reduced medullary hypertonicity 2. Absence or interference with ADH function 3. Osmotic diuresis
What is a condition that could produce reduced medullary hypertonicity?
Structural renal tubule damage - e.g. chronic kidney disease
What could cause absence of interference with ADH function?
Primary ADH deficiency - central diabetes insipidus
What could cause osmotic diuresis?
The tubular filtrate contains greater than normal number of osmotic particles - diabetes mellitus - lot’s of glucose in urine
What is the definition of dysuria?
Difficult or painful urination
What is pollakiuria?
Voiding small quantities of urine with increased frequency
What is stranguria?
Straining to urinate
What is pigmenturia?
Discoloured urine
What is periuria?
Urination in an inappropriate location
What does dysuria indicate?
Disease of the lower urinary tract - does not exclude concurrent involvement of URT i.e. pyelonephritis
What are the major alternative diagnosis for dysuria in dogs?
- Bacterial cystitis (lower UTI) 2. Prostatic disease 3. Urolithiasis 4. Bladder or urethral neoplasia 5. Urinary tract obstruction (mechanical - urolith, functional - neurologic disease)
What are the major differentials for feline LUTS?
- Idiopathic urinary tract inflammation (approx. 55%) 2. Urinary tract obstruction 3. Urolithiasis 4. Bacterial cystitis (variable - up to 20%) 5. Anatomic defects - previous urethral injury 6. Neoplasia (rare)
What is urinary incontinence?
Disorder of the storage phase of micturition
What is urinary retention?
Disorder of the voiding phase - residual urine left in bladder after urination
