Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HMS Homeostasis II > Proteinuria and Nephrosis > Flashcards

Proteinuria and Nephrosis Flashcards

1
Q

“Overfill theory” of edema in nephrotic syndrome

A
  • Now accepted as the correct theory
  • Based on the empirical observation that in models of podocyte injury and proteinuria, proteinuria causes sodium retention within the collecting duct
  • This is believed to be due to plasmin from serum activating ENaC directly
  • This salt retention is then what drives the edema in nephrotic syndrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is going on in this urine microscopy?

A

“Muddy brown” casts

These casts are highly suggestive of a condition called acute tubular necrosis, which can occur in the setting of severe, acute kidney injury from ischemic damage to the kidneys or agents that are toxic to the tubular cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

If someone has renal failure that resolves by giving fluids, then it is by definition ___.

A

If someone has renal failure that resolves by giving fluids, then it is by definition pre-renal azotemia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is going on in this polarized-light urine microscopy?

A

A fatty cast

Fatty casts examined under polarized-light show a Maltese cross appearance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is going on in this urine microscopy?

A

A white cell cast

WBC casts can be seen with acute interstitial nephritis and glomerulonephritis.

Urinary tract infections can very rarely have WBC casts. Instead, WBCs are found in clumps, rather than true casts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Urine specific gravity

A
  • Broadly reflective of increased solute density
  • The specific gravity of water is 1.000 so urine that is very dilute may be close to this at 1.005 whereas concentrated urine would be 1.030
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Prerenal azotemia vs ATN

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Spot urine test

A

Attempts to overcome protein variability in urine by measuring the protein in relation to urinary creatinine. This test also measures all protein, not just albumin.

The average amount of creatinine excreted in one day is approximately 1 gram, which consequently means that the ratio of urinary protein to urinary creatinine approximates the number of grams of urinary protein in one day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is going on in this urine microscopy?

A

Uric acid crystals

Uric acid is very insoluble in an acid urine and forms these rhomboid shapes (different from the needle shapes seen in a joint with gout)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Glomerular damage nomenclature

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Urine sodium and the Fractional Excretion of sodium (FENa+ )

A
  • Urine sodium measures used to assess whether or not the kidney has appropriately adjusted to hypovolemia
  • FENa+ is related to the following equation:
    • FENa+ = (PCr * UNa ) / (PNa x UCr) x 100
  • It relates the relative excretion of sodium from plasma into urine to that of creatinine
  • Should be <1% in a hypovolemic patient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If a child presents with the nephrotic syndrome you should. . .

A

. . . presume they have minimal change disease and treat with empiric prednisone.

If the patient does not respond within 8 weeks, then biopsy may be warranted.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Minimal change nephrotic syndrome

A
  • Ultrastructural damage to podocytes causing loss of proper filtration slit diaphragm function
  • Results in severe proteinuria and nephrosis
  • Can’t be seen on normal histology, requires transmission electron microscopy for diagonsis
  • Occurs most frequently in children, but 2nd peak later in life
  • Responds very readily to corticosteroids
  • But, may relapse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Isosthenuria

A

When urine always has a similar osmolarity to blood. Indicates renal failure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Formulas used to estimate the GFR can only be used . . .

A

Formulas used to estimate the GFR can only be used in the steady state.

Therefore, in the acute setting, it is impossible to calculate a GFR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is going on in this urine microscopy?

A

A red cell cast

Note that the cells in this red blood cell cast are uniform in shape and size and have no internal structures. Red blood cell casts are pathognomonic for glomerular bleeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Only ___ hydronephrosis causes post-renal failure.

A

Only bilateral hydronephrosis causes post-renal failure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Focal and segmental glomerulosclerosis nephrotic syndrome

A
  • May begin as a minimal change nephrotic syndrome, BUT
  • Characterized by complete loss of podocytes, either due to apoptosis or falling off into the urinary space or both
  • This will then result in scarring of the glomerulus
  • Thus, unlike minimal change, this will be apparent on H and E
  • Like minimal damage, believed to be caused by some circulating factor that is yet unknown
19
Q

What is going on in this image from urine microscopy?

A

The arrowhead shows a crenated erythrocyte.

These are seen in concentrated urine, and are not consistent with a glomerular origin of hematuria.

20
Q

What is going on in this image from urine microscopy?

A

There is an acanthocyte highlighted by the arrow (basically just a red blood cell with blebs)

These are consistent with glomerular hematuria,

21
Q

Estimated GFR in dosing for penicillin

A
  • If the estimated GFR is 10-50 ml/min, only 75% of the normal dose should be given
  • and if the GFR is <10 mL/min, 50 % of the dose is given with a longer interval between doses.
22
Q

What is going on in this urine microscopy?

A

A fatty cast

This is a lipid-laden cast or a fatty cast, commonly seen in heavy proteinuria and the nephrotic syndrome.

23
Q

Example urine dipstick

A
24
Q

Proteinuria indicates. . .

A

. . . disruption of the glomerular capillary wall

25
Q

What is going on in this urine microscopy?

A

Fine granular casts

Cellular debris can also be incorporated into cast forms. These appear to be granules rather than cells

26
Q

Three major categories or acute kidney injury

A
  • Prerenal azotemia (problem with kidney perfusion)
  • Intrinsic renal disease (true problem with the renal parenchyma)
  • Post renal failure (problem in urinary tract)
27
Q

How does the urine dipstick measure blood?

A

It measures hemoglobin or myoglobin in the urine.

28
Q

What is going on in this urine microscopy?

A

Calcium oxalate crystals

Calcium oxalate crystals may be seen in patients in normal individuals, with hypercalciuria or from hyperoxaluria. They commonly take on a “envelope” shape, but can also form other distinct shapes.

29
Q

FE Na+

A

Urinary Na+-to-creatinine ratio.

<1 indicates prerenal azotemia. >3 indicates acute tubular necrosis.

30
Q

Most common causes of nephrotic syndrome

A
  1. Minimal change disease
  2. Focal and segmental glomerulosclerosis
  3. Membranous nephropathy
31
Q

Urine output

A
  • Measured in vol/hour
  • Measured relative to body weight in children
  • Oliguria = low urine output, often defined as less than 0.5 mL/kg/hr for at least 6 hours
  • Anuria = absent urine output, or less than 50-100cc/24h, indicates severe renal failure
  • In the majority of adults, 600 mL per day is the requisite volume needed to excrete waste and serves as an approximate cut-off between normal urine output and oliguria
32
Q

Assessing for proteinuria

A
  • Usually albumin is measured specifically, since it is the major protein
    • Limitation to this is if there is an excess of light chain, which would be missed
  • If a single measurement is being used, it is subject to variability. If the urine flow rate is high (the urine is dilute), the urinary protein can be underestimated, and if the urine flow rate is low and the urine is concentrated, the urinary protein can be overestimated.
  • Instead, traditionally, proteinuria would be characterized by asking a patient to collect urine for 24 hours but this may be challenging for patients.
33
Q

Microalbuminuria

A
  • The urinary dipstick does not detect very small amounts of urinary albumin, yet small amounts of albuminuria may herald the beginning of significant renal disease and this is particularly true in diabetes mellitus.
  • To address this, the urinary albumin to creatinine ratio is used instead
  • Reference is generally in the 30 μg/mg creatinine to 300 μg/mg creatinine
  • This test is an immunoassay and detects only albumin
34
Q

Uromodulin

A

A protein made in the tubules which may form casts of the nephric tubules.

35
Q

Nephrotic range proteinuria

A
  • When proteinuria is more than 3.5 grams/day (or a ratio of 3.5 g/g), this is considered “nephrotic range proteinuria.”
  • IF the patient also has a low serum albumin and edema, then the patient has the nephrotic syndrome
36
Q

In the setting of setting of chronic kidney disease, the causes of the altered renal function may be assessed by. . .

A
  • Estimating the GFR
  • Assessing urine sediment
  • Quantifying proteinuria
37
Q

How does the urine dipstick measure leukocytes?

A
  • The dipstick measures leukocyte esterase
  • When this is positive, this suggests that white blood cells (WBCs) are present in the urine, also known as pyuria
  • Can be a sign of UTI, glomerulonephritis, interstitial nephritis, or generalized kidney inflammation
  • Should be confirmed with a sediment
38
Q

Membranous nephropathy nephrotic syndrome

A
  • Autoantibody against podocyte antigen, often phospholipase A2 receptor
  • Immune complex formed within glomerulus, resulting in activation of complement
  • Since ICs are on the urinary side, immune cells cannot clean them up!
  • The result is overproduction of basement membrane to try and encase the ICs
  • Once basement membrane damage occurs, it is irreversible
  • Identifiable on H and E by the thick, bubble-like basement membrane of the capillaries, and identifiable by silver stain due to basement membrane “spikes”
  • Treated with immunosuppressants
  • 1/3 spontaneous remission, 1/3 partial remission, 1/3 progressive
39
Q

How does the urine dipstick measure protein?

A

It only detects albumin.

40
Q

Evolution of ApoL1 in East African and West African populations

A
41
Q

What are the problems with the “underfill” theory of edema?

A
  • When empirically observed, renin and aldosterone are not usually high in these patients
  • They tend to recover before albumin does, suggesting albumin is not the only contributor
  • Other diseases causing hypoalbuminemia do not present with edema
  • Analbuminemic rats exist and do not have any observable edema
42
Q

“Underfill theory” of edema in nephrotic syndrome

A

Low oncotic pressure due to hypoalbuminemia results in loss of intravascular fluid to the interstitium as edema, which is then compensated for by RAAS activation and sodium and water retention.

43
Q

What is going on in this urine microscopy?

A

Hyaline casts.

These are best seen with the microscope light at a low level. Hyaline casts are non-specific and may be normal but can often form in the setting of reduced flow as with reduced renal perfusion.

HMS Homeostasis II (35 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions