Nephrology: Proteinuria and Hematuria ( Lect. 1/2) Flashcards
List the cellular layers that a protein must traverse to reach the proximal tubule if it starts within an afferent arteriole ?
Capillary endothelium: has fenestrations(pores) that are large enough for protein molecules to traverse, however under normal conditions they do not.
Capillary endothelium basement membrane: typically negatively charged due to glycocalyx, heparin sulfate and other - charged proteins. This helps stop the outflow of plasma proteins into Bowmans Space.
Podocyte: Has foot processes that wrap around the capillary. Aids in filtration and helps select out larger molecules so that they do not go into Bowmans space.
What is the normal 24 hr protein excretion ?
60-150 mg (so its false that all proteins cannot be filtered, there is some filtration just of smaller particles)
What percent of daily protein excretion is albumin ?
15% (10-20 mg)
What are the more frequently excreted proteins found in the urine ?
Small molecular weight
Light Chain
Immunoglobulins
Which proteins are not filtered ?
Tamm-Horsfall proteins (if these are present it is indicative of pathology)
Colorimetric reaction based on the chemical interaction between Tetrabromophenol Blue in citric acid buffer with urinary albumin. What is a positive and negative reading on this dipstick ?
Green –> Negative
Blue–> Positive
What is the only protein measured by Tetrabromophenol blue ?
ALBUMIN ! The dipstick is only useful for reading this !
Describe the Number Scale used for quantifying amount of albumin in the urine
Trace 10 – 20 (30?) mg/dl (only truly important in diabetes and heart disease unless persistent.)
1+ 30 (100?)mg/dl
2+ 100 (200?) mg/dl
3+ 300 mg/dl
4+ 1000 mg/dl
To estimate the 24 hr protein concentration of the urine, multiply the number scale value by 10. Ex. If you have a 2+ dipstick value then you know that you have a 100 mg/dl, So 100 x 10 = 1000 mg/Day.
There is some discrepancy between Slide 11 and 12 on what the Number value coo relations are, which is why I put these in parentheses.
Why is hematuria a confounding problem in urinalysis of albumin ?
When RBC’s are lost into the urine there is inevitably going to be excess albumin lost with it. This will skew your reading to be higher then it should be.
The reading for albumin in albuminuria with concurrent hematuria will be always be higher (than without )unless there is a true loss of albumin not linked to hematuria.
What is the level of protein in the urine which delineates between microalbuminuria and macroalbuminuria ?
> 300 mg/day !
30-300 mg/day is microalbuminuria, anything above this is macro.
If the urine dipstick is positive what do you automatically have ?
Macroalbuinuria ( Trace 10-30 mg/dl. 30 x 10 =300)
Despite 24 hr collection being the “Gold Standard” for Urinalysis. What technique is becoming more useful ?
Spot Random Collection (protein/Creatinine ratio)
Should do this earlier in the morning rather than in the afternoon.
Proven to be just as efficacious as 24 hr collection.
What are the four classifications of proteinuria ?
Tubular
Overflow
Orthostatic
Glomerular
Tubular
Amount: .5-2 mg Type of Protein: B2-microglobulin, albumin HTN: None Renal Failure: Mild Hematuria:no
Overflow
Amount: .5- > 3g Type of Protein:Light chain immunoglobulin (kappa- delta) HTN: None Renal Failure: Marked Hematuria: No
Orthostatic
Amount: .5-2g Type of Protein: Albumin HTN: No Renal Failure: No Hematuria: No
Glomerular
Amount: > 3.5 mg Type of Protein: Albumin HTN: VERY HIGH Renal Failure: Moderate Hematuria: Moderate
All patients with proteinuria must have what labs/diagnostics done ?
Serum creatinine
Urine microscopy
Fatty Casts and oval bodies are indicative of which syndrome ?
Nephrotic Syndrome ( nephrOtic = Oval bodies, Fat Casts (fat people are round like and O))
You may also see Cholesterol Crystals in nephrotic syndrome.
RBC casts and dysmorphic RBC’s are indicative of which condition ?
Glomerulonephritis
Leukocytes, PMN’s and White blood cell casts indicate what condition ?
Infection
Leukocytes and eosinophils indicate what condition ?
Interstial Nephritis
Foamy urine ?
Protein in it –> Albuminuria
What is a Fatty Cast ? (Starred)
Cholesterol deposit on Tamm-Horsfall Protein
Remember: Fatty Cast = nephrOtic syndrome
What is an Oval Fat Body ? (Starred)
Cholesterol on Renal Tubular Cells
Remember Oval Fat Body = nephrOtic syndrome
Which two conditions diagnosed by bloodwork are often seen in Nephrotic Syndrome ?
Hypoalbuminemia ( due to loss in the urine)
Hypercholesteremia (Cholesterol is present in Fatty Casts and in Oval Bodies)