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59 Cards in this Set
- Front
- Back
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normal amt of protein lost in urine
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< 150 mg/day
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total amount of plasma protein that goes through collective glomeruli
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50 million mg/day
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glomerular filtration barrier
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prevents this large amount of plasma protein that is going through the glomeruli to being filtered into the tubular fluid
3 layers: fenestrated glomerular capillary epithelium; glomerular filtration membrane; podocytes |
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fenestrated glomerular capillary endothelium
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fenestrations are numerous in capillary wall
make glomeruli 50x more leaky than capillaries located other place in the body -permit plasma constiutents to be filtered into bowman's capsule and proximal tubule |
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how many capillaries are in each glomeruli?
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50-100
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Glomerular Basement Membrane (GBM)
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part of the GFB (glomerular filtration barrier)
attached to outside of the capillaries negative charge |
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podocytes
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AKA: visceral epithelium
-epithelial cells with foot projections attached to outside of Basement membrane -thin "slit membrane" bridges gap between any 2 adjacent foot processes |
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size barrier
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created by fenestraes and gaps between foot processes
-minimum hole is 7nm |
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molecules >4nm
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unable to pass through gaps -- witheld due to the SIZE BARRIER
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main components of plasma protein
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-Albumn and IgG
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Albumin and IgG
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are small enough to fit through gaps (size barrier) but can't go through because they are repelled due to the charge barrier (they are negatively charged at physiological pH, and the 3 components of the GFB are also negatively charged)
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How much of the plasma proteins that get filtered into the urine gets reabsorbed? Where does this take place?
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98% get reabsorbed, this takes place in the proximal tubule
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what happens in the process of reabsorption of plasma proteins in the proximal tubule?
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molecules are endocytosed into the tubule cells, hydrolysed in their lysosomes, and returned to interstitun as amino acids and small peptides. next, tehy are picked up by the peritubular capillaries and returend to circulation
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compositions of the 150 mg/day protein that is filtered into urine
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40% albumin
40% Tamm-Horsfall Proteins |
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Tamm-Horsfall proteins
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glycosylated protein secreted by ascending thick limb of each nephron
major component of hyaline casts from normal urine from normal kidneys |
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urinary cast
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small, cylinder of proteins or cells that forms within tubular fluid and takes the shape of the tubular lumen and gets excreted into the urine.....
several types- all except hyaline are indicative of some type of renal dysfunction |
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presence of urinary cast (except hyaline, which is normal)
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evidence of one form of renal function or another
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intrinsic renal disease categories
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1. glomerulonephritis
2. acute tubular necrosis 3. interstitial nephritis |
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significant amt of protein found in urine is indicative of...
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glomerular disease, or glomerulopathy
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found in urine w. glomerulopathies
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Protein
RBC - RBC casts or dysmorphic RBC **shouldn't be there because the GFB should prevent them from filtering into tubular fluid |
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urine dip
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in office; first sign of proteinuria
-urine reagant strip with chemical indicators that change color due to presence of certain moeties in the urine similar to litmus paper |
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moeities tested with urine dip
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protein
glucose blood albumin ketones leukocyes nitries bilirubin urobilirubin pH specific gravity |
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Gross Hematuria (in regards to a urine dip)
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can give a FALSE POSITIVE result of protein in the urine, because 1 ml of whole blood contains 50 mg of protein
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How is protein content rated with a urine dip?
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Negative: <10mg/dL
Trace: 10 mg/dL 1+:30 mg/dL 2+:100 mg/dL 3+: >500 mg/dL |
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What is the total daily urinary protein loss of a urine dip result of "trace"
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150 mg/day -- which is the upper limit of "normal" (most people have less than that)
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"Trace" of protein in a urine dip
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indicates 10 mg/dL concentrated urine, and 150 mg/day protein loss
-must get a 24 hr urine sample to get a more precise measurement of total urinary protein |
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24 hour urine sample
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gives a more precise measurement of total urinary protein
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spot urine for protein/creatinine ratio
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-easier than 24 hr urine sample: for infants, young children, and elderly
-Expected value is 0.1, so a value <0.2 is Healthy |
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Orthostatic Proteinuria
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Postural proteinuria
-increased protein excretion during the day (ambulatory, hihger BP, etc) than at night -24 hour urine sample wiht seperate alloquots for daytime and nightime urine. daytime urine:proteinuria night time urine (and first AM urine): no protein |
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Functional Proteinuria
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Caused by high fever, strenuous exercise (running a marathon, etc) or exposure to extreme cold
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Mechanisms of pathologic proteinuria
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1. loss of charge barrier
2. loss of size barrier 3. overload proteinuria 4. proximal tubular dysfunction |
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loss of >3.5 g/day of protein usually occurs because ...
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loss of charge barrier, size barrier, or both,
**HOWEVER, loss of either 2 could cause lesser protein loss.... ?? |
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selective proteinuria
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proteinuria due to loss of charge barrier
* caused by MCD |
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loss of charge barrier
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IgG/Transferrin ratio.
IgG is restricted by size barrier, whereas transferrin is restricted by charge barrier. IgG/Transferrin <0.1 means there is loss of charge barrier (selective proteinuria) |
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IgG
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protein constiuent that is repelled due to size barrier
-higher amount of IgG in urine, is indicative to proteinuria by loss of size barrier |
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Loss of Size Barrier
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IgG/Transferrin ratio >0.1 means there is loss of size barrier (non-selective proteinuria)
occurs in many diseased in which abnormal substances accumulate in glomeruli: 1. immunoglobin and IC: rheumatoid, SLE, etc 2. amyloid protein = amyloidosis 3. advanced end-stage glycosylation products= diabetes |
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non-selective proteinuria
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proteinuria due to loss of charge barrier
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overload proteinuria
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proteins that normally filter into tubular fluids in SMALL AMOUNTS and are immediately reabsorbed..when quantities are TOO LARGE TO BE REABSORBED, OVERLOAD PROTEINURAI OCCURS
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3 CHAINS commonly cause overload proteinuria
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1. light chains -- multiple myeloma--bence-jones proteins
2. myoglobin from rhabdomyolysis 3. hemoglobin from hemolysis |
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light chains
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in multiple myeloma, bence-jones proteins are formed (can't be detected with routine urine dip, must use electrophoresis)
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hemoglobin
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lysing of large numbers of blood cells (hemolysis) released more Hb than Haptoglobin (Hb binding protein) can handle, so Hb gets filtered into tubule fluid and proximal tubule can't reabsorb it all
-some hemolytic anemias cause filtration of Hb into tubular fluid |
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myoglobin
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rhabdomyolysis (breakdown of skeletal muscle)
-due to crushing injury or prolonged exercise -->myoglobin chains filtered into tubular fluid |
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positive urine test for "blood"
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upon microscopic analysis, if whole RBC are not found, the positive test resule was caused by either: hemoglobin (hemolysis) or myoglobin (rhabdomyolysis)
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proximal tubular dysfunction
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normal amount of protein is being filtered into the tubular fluid, but there is something wrong with the proximal tubule's absorptive capacity
-drugs, toxins, immune reactions, viral reactions can cause PTD |
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nephritic syndrome
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proteinuria <3.5 g/day
hematuria (macro or micro; RBC casts or dysmorphic RBC) decrease GFR= Azotemia=Increased Plasma creatinine and BUN levels HTN periorbital edema |
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Nephrotic syndrome
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proteinuria >3.5 g/day
little or no: hematuria, azotemia, or HTN hyperlipidemia=lipiduria hyperproteinemia=hyperalbuminemia generalized edema |
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presence of only ONE RBC cast in urine
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is indicative of GLOMERULONEPHRITIS
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How is edema caused?
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glomerulopathy permis excretion of large amounts of plasma protein --> FEWER SOLUTE PARTICLES in plasma water --> less oncotic suction/oressure-->WATER exits through capillary walls --> GENERALIZED EDEMA
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primary glomerulopathies
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present in themselves, not related to other diseases
both nephrotic and nephritic |
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neprhitic pimary glomerulopathies
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1.post infectious glomerulonephritis
2. IgA nephropathy (Berger's Disease) 3. Good pasture syndrome (Anti-GBM glomerulonephritis) |
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nephrotic primary glomerulopathies
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minimal change disease (lipid nephrosis)
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secondary glomerulopathies
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present as part of the morbidity of pre-existing systemic diseases
--Diabestes, SLE, Rheumatoid, Amyloidosis, etc |
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Generalities of ARF
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1. decreased renal function = decreased GFR = anuria, oliguria.
2. Decreased GFR = azotemia: Increased BUN and Plasma creatinine levels hematuria, proteinuria |
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How much does plasma creatinine levels increase per day with ARF?
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0.5 mg/dL per day
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How much does BUN levels increase per day with ARF?
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10 mg/dL per day
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Asymptomatic
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at first, ARF is asymptomatic, no aches or pains, patient just wonders why he/she is peeing so little
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ARF can become
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Uremia, which is symptomatic
can occur in as little as one week (Depending on how bad ARF is and how quickly it is treated) |
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Uremia
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Itchy, yellow skin (from urea)
peripheral neuropathy - stocking and glove paresthesia pericarditis -- chest pain failing kidneyes = decrease in erythropoiten = anemia acidemia weakenss, myalgia, vomittin, nausuea and anorexia |
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Post-Infectious Glomerulonephritis pathology
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=most commonly caused by IgG ICs formed during the infection (Are seen on GBM)
can also be caused by other infections. |
