Proteinuria and protein losing nephropathies Flashcards
What is proteinuria?
Excessive protein in the urine
Proteinuria = hyperproteinuria
What is albuminuria?
Excessive albumin in the urine
Albuminuria = Hyperalbuminuria
What is overt proteinuria?
Dipstick detectable excessive protein in the urine
Generally Over 0.3g/L
What is microalbuminuria?
Mildly excessive albumin the urine
It is higher than normal, but still below limit of detection of most conventional urine dipsticks
0.01 - 0.3 g/L
What are some causes of false positives and negatives when using urine dispticks?
False Positives
- Antiseptic contamination
- Damp reagent strips
- Very alkaline or very concentrated urine
False negatives
-Not sensitive for detection of proteins other than albumin
What urine protein:creatinine ratio is normal and abnormal?
UP:UC
Normal -Dogs and cats under 0.2 Definitely abnormal Dogs over 0.5 Cats over 0.4
Why is using the UP:UC more accurate?
Because it takes away the amount the animal is drinking out of the equation
What are the 3 categories of proteinuria?
Preglomerular
Glomerular
Postglomerular
What are 5 differential diagnosis for preglomerular proteinuria?
Multiple myeloma Leukaemias B-cell lymphoma Haemolytic crisis Rhabdomyolysis
What are 5 differential diagnosis for glomerular proteinuria?
Glomerulonephritis**
Hereditary nephropathies
Amyloidosis
Other glomerulopathies
What are 6 differential diagnosis for tubular proteinuria?
Drug toxicities -NSAID, aminoglycosides Pyelonephritis Heavy metal poisoning Acute tubular necrosis Fanconi syndrom Vesicuoureteral reflux
What are the categories for differential diagnosis of post renal proteinuria?
Lower urinary tract disease
-Infection, inflammation, calculi, neoplasia
Genital inflammation/infection
Once a patient has tested positive for proteinuria by dipstick, using free catch or catheter, what should you do next?
Repeat it by cystocentesis
If a patient has tested positive to proteinuria by cystocentesis using a dipstick, what should you then do?
Look at the sediment
-If active or inactive
What is an active urine sediment, and what should you look at next?
Has lots of cells and other sediment in it
-Look at lower urinary tract or tubular disease
What is an inactive urine sediment, and what should you look at next?
Not many cells or anything that interesting in it
-Look at serum chemistry and UP:UC
The more severe the UP:UC is, what is more likely the cause?
Mild under 2.0 -Mild glomerular, tubular, functional Moderate 2.0-5.0 -Glomerular, tubular Severe over 5.0 -Glomerular
Why is it important to diagnose glomerulonephritis?
To try and stop it progressing to renal failure , nephrotic syndrome and other adverse outcomes
If you find preglomerular proteinuria, what should you look for?
Dysporteinaemia
-Abnormal protein in blood
If you find glomerular proteinuria, what should you then look for?
Hypoalbuminaemia Hypercholestrolaemia High UP:UC Oedema Inactive urine sediment
Explain how a bacterial infection such as an incisor tooth root abscess could lead to polyarthritis, a UP:UC of 15, but an inactive urine sediment and concentrated urine still?
Bacteria present Start to die They go into circulation Immune system responds Forms Ab-Ag complexes These lodge into joints and the basement membrane of the kidneys
Describe the pathophysiology of nephrotic syndrome?
Starts with proteinuria This leads to hypoalbuminaemia Drop in blood oncotic pressure Body tries to increase pressure Get hypercholestrolaemia Peripheral oedema/ascites -But may not see it Lipiduria - uncommon
How can you definitively diagnose glomerulonephritis?
Evidence of glomerular proteinuria
Renal biopsy
Is it always important to get a definitive diagnosis?
No
Sometimes only need to have a rough idea
Especially true if you can only definitively diagnose by an invasive test like a biopsy
Only diagnose if it will change how they will be treated
Describe treatment of glomerulonephritis?
Want to attempt to identify and eradicate any underlying cause ACE inhibitor* High quality protein restricted food Anti-platelet therapy -E.g. low dose aspirin \+/- other antihypertensive drugs Omega-3 fatty acids -Anti-inflammatory \+/- Immunosuppressant therapy -E.g. Azathioprine \+/- anti-edema therapy if required -Frusemid, NOT prednisolone
Why when treating glomerulonephritis you should give an ACE inhibitor?
Post-glomerular arteriole is controlled by smooth muscle
The tighter it is, the higher the glomerular pressure and more protein is likely to leak out
ACE inhibitor relaxes this smooth muscle, which means that less protein leaks out and you get an increase in creatinine
What is the main cause of renal amyloidosis?
Idiopathic
What 2 breeds is renal amyloidosis a familial disease?
Chinese Shar-pei
Abysinnian cats
-In the renal medulla more than the glomeruli (upset architecture)
How do you treat renal amyloidosis?
Same as for glomerulonephritis
- Except maybe
- DMSO S/C x3/week
- Colchicine -makes them sick
What are the 4 major complications of glomerular proteinuria?
Renal failure
Hypercoagulable state
Thromboembolism
Systemic arterial hypertension
Do you get PU/PD from glomerular proteinuria?
NO
-You are loosing albumin and damaging renal tubules
How does glomerular proteinuria lead to a hypercoagulable state?
Leaks small protein and antithrombin III
-Becomes out of balance
What is the most likely place a thromboembolism will form as a result of glomerular proteinuria?
Pulmonary
