Lab Diagnosis Of Urinary Disease Flashcards
What is the endocrine output of the kidney?
Erythropoietin
Renin
Active Vit D metabolites
What is the GFR?
How is it investigated?
Rate that fluid moves from plasma to glomerular filtrate
Rate of clearance - Createnine, Inulin (injected)
What is GFR proportionally affected by?
Renal plasma flow
Affected by renal perfusion
What is Azotaemia?
An increase in the non-protein nitrogenous compounds, usually UN and Createnine in the blood (uric acid in birds)
What is uraemia?
AZOTEMIA + CLINICAL SIGNS
What pathology is associated with uraemia ?
Loss of functional nephrons
What clinical signs are associated with uraemia?
Anorexia, V+D, GI haemorrhage, ulcerative stomatitis
Bruxism in ruminants - excessive teeth grinding/jaw clenching
What causes the decrease in renal function in renal failure?
Decrease in numbers of functioning nephrons
When should you take urine samples in relation to initiation of IVFT?
BEFORE IVFT
When would cytology be indicated ?
To investigate the potential for neoplastic processes affecting the kidney.
What elements of a biochem profile are we interested for urinary function?
UN Createnine Phosphorous Calcium Sodium Chloride Potassium Acid Base Protein
What should you look at concurrently when you look at the urine?
Serum/plasma chemistry
What affects urea levels?
Production in liver
Excretion in kidney
Protein levels
GI bleeding
What affects Createnine levels?
Kidney excretion
Muscle mass
What largely causes increased urea nitrogen?
Reduced GFR
Why does UN increase in dehydration ?
Passive diffusion back into blood increased as decreased urine flow rate
How should renal disease be assessed on biochem in cows?
Why?
CREATENINE
Can have severe dz with relatively normal UN as urea excreted into rumen -> ammonia -> aas -> protein production
Therefore urea low even if kidney dz
How long does Createnine take to equilibrate?
Around 4 hours
How can you determine if a uroabdomen is present from Abdominocentesis of fluid?
CREATENINE higher than serum levels
How much of renal function must be lost before a change in Createnine is seen?
How would you describe this in terms of specificity and sensitivity?
3/4
Low sensitivity - low true negatives
What are the types of Azotaemia?
Prerenal
Renal
Postrenal
What is prerenal Azotaemia?
Result of reduced RENAL PERFUSION
Or increased PROTEIN CATABOLISM
What causes prerenal Azotaemia?
Decreased blood pressure -> vasoconstriction -> reduced renal perfusion
What is renal Azotaemia?
Azotaemia due to renal disease and nonfunctional nephrons
What is postrenal azotaemia?
azotaemia caused by interference with the excretion of urine
—obstruction
— post renal leakage e.g. rupture
What can cause pre-renal azotaemia?
Increased protein catabolism: — GI haemorrhage — necrosis — starvation — corticosteroids
High protein diets
REDUCED RENAL PERFUSION
What would you expect the USG to be in pre-renal azotaemia?
Why?
HIGH
ADH response occurs and kidneys concentrate urine
What clinical signs are typically associated with post-renal azotaemia ?
Oliguria or anuria
How can you determine which type of azotaemia is present?
USG
Concentrating ability assessment
Compare urine with serum/plasma Createnine
What can falsely increase USG?
If there is glucose or protein in the urine
Needs to be calibrated to urine that doesn’t have abnormal constituents
What does a low USG indicate WITH azotaemia ?
RENAL FAILURE - decreased concentrating ability
What is isosthenuria?
Fixed USG 1.008-1.012
Osmolality same as plasma, no resorption
What is hyposthenuria?
Where is the problem?
USG <1.008
DILUTING ABILITY RETAINED
problem is in the collecting duct
What can cause normonatraemia?
Normal blood Na/normal blood water
Increased/increased
Decreased/decreased
What is the main ion in extracellular fluid?
Sodium
Where is most sodium resorbed?
Proximal tubule
What causes hypernatraemia?
Increased sodium intake
Reduced water intake or increased water loss
What causes hyponatraemia?
Reduced sodium intake
Increased sodium loss
Increased water intake
What usually coincides with changes in sodium?
Changes in chloride
When might you see changes in chloride without changes in potassium?
VOMITING
Acid/base status alteration
When does potassium increase ?
Acidosis - H+ swapped for K+ in blood
ACUTE Renal failure — ESPECIALLY if anuria and oliguria are present
Hypoadrenocorticism
When does potassium decrease?
Chronic kidney disease - PD/PU
Why do dogs and cats with renal failure often have a metabolic acidosis?
Kidneys usually conserve filtered bicarbonate
What makes up total calcium?
Free
Bound to albumin
Bound to anions
What can cause a decrease in albumin bound calcium?
Albumin loss - PLN
What can mask a decrease in free calcium on total calcium in renal failure?
Increased amount bound to anions
Which animals get all their calcium from their diet?
Where is it ALL excreted?
Horses and rabbits
Kidneys
What will calcium levels be in the following animals in renal failure:
Dog
Cat
Cow
Horse
Dog cat cow - hypo
Horse - Hyper
How does decreased GFR affect phosphate levels?
How may this differ in horses?
Hyperphosphataemia
HypO
What changes may be seen normally on biochem in normal growing animals ?
Hyperphosphataemia
Hypercalcaemia
Increased ALP
How does increased phosphate affect 1 alpha - hydroxylase ?
DECREASES
Outline secondary renal hyper parathyroidism.
Decreased GFR
Increased phosphate
Decrease 1a-hydroxylase activity
Decrease active vit D3
Decrease Calcium absorption and Calcium conc
Increase PTH
Phosphaturia + Increase 1 a-hydroxylase + increase calcium absorption
Describe the biochem seen in secondary renal hyperparathyroidism.
Initial damage
Slight PTH increased
Additional damage
Further PTH increase
Renal failure
Hyperphosphataemia
Reduced D3
Hypocalcalcaemia
High PTH
How does kidney disease affect amylase and lipase?
Normally cleared by kidney so INCREASE
Why is anaemia associated with renal disease?
DECREASED EPO
Describe the anaemia of renal disease.
Mild (HCT not lower than 30)
Normocytic and normochromic
NON-REGENERATIVE
When might cytology be indicated
investigate potential RENAL LYMPHOMA
- If both kidneys enlarged
BLADDER NEOPLASIA
What diets are associated with lower pH urine?
High protein
Fasting
What diet is associated with a higher pH urine?
Vegetable
What pH would you expect in urine of patient with cystitis?
Higher
Urea converted to ammonia by bacteria
What are the types of proteinuria ?
Prerenal
Glomerular
Tubular
Haemorrhagic or inflammatory (postrenal)
When might you see glucosuria?
Hyperglycaemic glucosuria (e.g. DM)
Renal glucosuria
Stressed cats
When might you see ketonuria?
Poorly controlled diabetics
When might you see bilirubinuria?
Haemolytic anaemia
Liver disease with cholestasis
Gall bladder/bile duct obstruction
How would you interpret bilirubinuria in dogs and cats?
Dogs - small amount not a concern
Cats - ALWAYS significant
What is haematuria?
What causes?
Intact blood cells in urine
Trauma, cystitis, renal or genital bleeding
(Can see intact RBCs in spun sample)
What can you see in sediment?
Cells, crystals, casts, bacteria
What do white blood cells in sediment indicate?
Inflammation or infection
Why might there be RBCs in urine sediment?
Haemorrhage
Contamination from cystocentesis
