Proteinuria in cats Flashcards
What are the different methods of assessment for proteinuria
Urine dipsticks
- rapid, semi-quantitaive assessment of proteinuria
- dipsticks are more sensitive to albumin than other proteins
- unreliable for low proteinuria (frequent in cats)
- result needs to be interpreted according to USG
The sulfosalicylic acid precipitation test
- semi-quantitative test
- not usually used in clinic
- mix equal volumes of urine and 5% solution of SSA and assess the resulting turbidity
- specific but not sensitive
UPC
- measurement of UPC ratios from spot urine samples are very closely correlated with results of 24h collections
Albumin assay
- species specific
- measured by ELISA methods
How can you categprize proteinuria
The causes of proteinuria can be broadly categorized as pre-renal, renal or post-renal in origin
What is pre-renal proteinuria
Pre-renal proteinuria occurs when an increased amount of low molecular weight protein passes into the primary glomerular filtrate
- immunoglobulin light chains
- haemoglobin
- myoglobin
What is renal proteinuria
Proteinuria of renal origin is classically consideed to be the hallmark of glomerular disease
Low-level proteinuria may also arise as a result of tubular dysfunction, which leads to a failure to process and reabsorb the small amount of protein, mainly albumin, which traverses the glomerular barruer
The amount of protein that traverses the glomerular filtration barrier depends not only on the structural integrity of that barrier but also on the hydrostatic pressure that is applied to it (e.g., glomerular hypertension secondary to systemic hypertension, glomerular hyperfiltration seen with loss of nephrons
What is post-renal proteinuria
Post-renal proteinuria occurs when protein is added to the urine after its formation in the kidney
- inflammation of the bladder is the most common cause
The magnitude of post-renal proteinuria is highly variable thus in patients with LUTD proteinuria should not be thought of being post-renal in origin systematically
- if the urine sample is not visibly discoloured with blood then the protein measurements will not be altered
Explain why ACE inhibitors are beneficial in slowing progression of renal damage in CKD
The benefit is most marked in patients that are proteinuric
It is thought to be due to the preferential dilation of the efferent arterioles within the kidney, which act to reduce glomerular hypertension and therefore also reduce proteinuria
