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Renal > Approach to a Patient with Renal Disease > Flashcards

Approach to a Patient with Renal Disease Flashcards

1
Q

What 2 findings in clinical presentation are DIRECTLY referable to the kidney?

A
  1. proteinuria

2. increased serum creatinine

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2
Q

What are the 3 steps to determining if a patient has renal disease?

A
  1. Assess the duration
  2. Measure renal function to determine if there has been a loss and if so, to what degree
  3. Identify the specific syndrome on the basis of history, physical and urinalysis/lab values/imaging
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3
Q

What 5 things are used to determine the duration of disease?

A
  1. old records
  2. kidney size
  3. renal osteodystrophy
  4. biopsy
  5. anemia & hyperphosphatemia (less useful)
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4
Q

Why is it crucial to differentiate acute from chronic renal disease?

A
  1. Acute is self-limiting

2. treatments vary depending on if the disease is recent onset or longstanding

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5
Q

How are old medical records used to determine duration of kidney disease?

A

They can be used to see how :
creatinine
proteinuria
hematuria

progress with time

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6
Q

How is kidney size measured? What is normal?

What will the size be in acute vs chronic kidney disease?

A

It is measured by renal sonography or plain film of the abdomen.
Normal kidneys are roughly 12-14 cm in total length and symmetric.

Small kidneys (<8cm) are a certain sign of chronic disease because chronic is associated with fibrosis and sclerosis

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7
Q

What is renal osteodystrophy and what is it associated with?

A

Renal osteodystrophy is also called Chronic Kidney Disease- Mineral and Bone Disorder (CKD-MBD).

Electrolytes and endocrine derangements from the chronically diseased kidney cause bone resorption and bone pain.
The serum Ca and vitD are low and the serum phosphate and PTH will be high

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8
Q

What is the most precise way to differentiate acute kidney disease from chronic?

A

A renal biopsy is the gold standard.
It is not practical/necessary in most cases but is useful in patients suspected of CHRONIC renal failure bc of their history, but has normal size kidneys on imaging

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9
Q

What is the best measure for assessing renal function?

A

GFR is considered the best measure.
Serial assessments allow the physician to determine the course of the disease by demonstrating rapid or slow decline of kidney function.

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10
Q

What is measured in the serum as a surrogate for GFR? Why?

What are normal values for men and women?

A

Creatinine concentration varies inversely with GFR. (more creatinine in serum, the lower the GFR)

Men : 0.8-1.3 mg/dl
Women: 0.6- 1.0 mg/dl

(men will have higher creatinine because it is a product of creatine. men tend to have higher muscle mass)

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11
Q

What are 3 major limitations of using serum creatinine level in the assessment of renal disease?

A
  1. It is insensitive to mild reductions in GFR because the relationship between creatinine and GFR is non-linear.
    For example: a change in Cr from 0.6 to 1.2 reflects a 50% decrease in GFR but 1.2 is still a normal Cr level so it may not draw attention.
  2. It is slow to reflect acute changes
    For example: a rapid GFR drop from 100 to 10 would take 7 days to show up in serum
  3. it is dependent on muscle mass
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12
Q

What is a more accurate method to assess GFR than measuring serum Cr?

A

Measuring a 24 urine collection for creatinine clearance
Cr is filtered and a tiny amount is secreted. It is NOT reabsorbed. It is fairly accurate for GFR but it may show a slightly elevated value

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13
Q

How is CCr measured?
What are the normal values for women/men?

What would cause the creatinine clearance to overestimate GFR?

A

Creatinine clearance (ml/min) = urine creatinine (mg/dl) x urine volume/plasma creatinine x 1440

Men: 125 +/- 25 ml/min
Women: 95 =/- 20 ml/min

CCr overestimates GFR in patients with chronic kidney disease because creatinine reaching the tubule via secretion increases.

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14
Q

What are the 3 major limitations of using creatinine clearance for assessing GFR/kidney function?

A
  1. It can overestimate GFR in patients with CKD becaue there will be a larger secretion
  2. It will be falsely decreased in patients on trimethoprim or cimetidine because these drugs inhibit secretion
  3. Most patients do not accurately collect urine samples
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15
Q

How can you assess if a patient is accurately collecting urine samples?

A

Normal daily rate of Cr excretion is 20 mg/kg lean body weight

If the excretion is SIGNIFICANTLY less than normal, this indicates incomplete urine collection
If it is significantly more than normal it indicates over collection

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16
Q

Why does prolonged storage of urine invalidate urinary CCr measurements?

A

high temps and low pH cause creatine to convert to creatinine in the urine giving falsely high urine creatinine levels

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17
Q

How can CCr be estimated at bedside without having to take urine samples/serum measurements?

When can these estimation NOT be performed?

A
  1. (140-age) x (IBW in kg)/(72x pCr)

or

  1. MDRD equation

You cannot use these equations if the patient is not in steady state (serum Cr is changing day to day)

18
Q

What is the BEST substance to measure GFR? Why is it not frequently used?

A

Inulin is the best measure for GFR because it is freely filter, not reabsorbed and not secreted.

Cin = urine inulin x (volume urine/plasma inulin)

It is not frequently used because it is an exogenous substance (from chicory) so it must be continuously administered via infusion to get it to steady state.
COST AND LIMITED SUPPLY

19
Q

Do the following symptoms hint at pre-renal, intra-renal or post-renal?

-vomiting, diarrhea, blood loss, thirst, orthostatic hypotension, decreased JVP, dry mucous membranes, and skin turgor

A

pre-renal

20
Q

Do the following symptoms suggest pre, intra or post renal?

  • polyuria, dyspnea, edema, nocturia, nephronlithiasis, hypertension, retinopathy, rales, S3 gallop, edema, increased JVP?
A

post renal

21
Q

What are the 4 possible locations of intra-renal disease?

A
  1. acute tubular necrosis
  2. tubulointerstitial
  3. glomerular
  4. vascular
22
Q

What are the 5 potential glomerular renal diseases?

A
  1. asymptomatic hematuria/proteinuria
  2. acute glomerulonephritis
  3. chronic glomerulonephritis
  4. nephrotic syndrome
  5. RPGN
23
Q

What is the major non-invasive diagnostic tool for assessing renal disease? What are limitations?

A

Urinanalysis can give info about what disease is present and what the severity is, however, it is not always a good assessment of severity.

ex. acute glomerulonephritis can resolve and the patient can have normal urinalysis, but they may have fibrosis/scarring and nephron loss. CCr will not show nephron loss because of hypertrophy/hyperfiltration in the currently working glomeruli

24
Q

How is urinalysis performed?

A
  1. mid stream sample from men, clean external genitalia in women to avoid contamination
  2. centrifuge at 3000rpm for 3-5 minutes
  3. pour supernatent into separate tube to test for proteins, glucose, heme, concentration
  4. place sediment on slide to analyze

Samples should be analyzed within 30-60 minutes of peeing

25
Q

How are proteins detected in urine?

A
  1. Urine dipstick detects negatively charged proteins (like albumin)

Patients with increased excreting of cationic non-albumin proteins in the urine (Ig light chains with MM) will have negative or trace urine dipstick

  1. SSA (sulfosalicylic acid) will detect all proteins

(neg dipstick, positive SSA –> positive protein excretion)

26
Q

Urinalysis shows:
SG: 1.020
Glucose, protein negative
Hyaline casts

The patient has low JVP and othostatic changes in pressure.

What is the likely problem?

A

They specific gravity is normal/elevated meaning that the kidneys are concentrating urine.
This implies low volume and ADH retaining water.

Hyaline casts indicate pre-renal disease

27
Q 
A patient presents with decreased urine flow.
Urinalysis shows:
SG: 1.007
protein negative, blood negative 
0-3 RBC/hpf, 0-3 WBC/hpf

What is the likely problem?

A

post-renal disease

The SG is low because the increased perceived volume will decrease ADH insertion and the urine will be dilute

28
Q

A patient has been exposed to radiocontrast, aminoglycosides, cisplatinum OR has been hypoxic.

Urinalysis shows:
SG: 1.010
trace proteins, blood negative
1-3 WBC/hpf
"muddy brown pigment" granular casts
5-10 renal tubular casts, renal tubule cells

What is the problem?

A

Acute tubular necrosis

29
Q

A patient presents with edema and hypoalbuminemia.

Urinalysis:
SG: 1.015
protein 4+
oval fat bodies, fatty casts

What is the likely problem?

A

Nephrotic syndrome:

  • MCD
  • FSGS
  • MGN
  • diabetic nephropathy
  • amyloidosis

possibly MPGN, DPGN

30
Q

A patient presents with fever, morbilliform rash, recent antibiotic administration.

Urinalysis:
SG: 1.012
protein +1
blood +2
20-30 WBC/hpf
eosinophils
WBC casts
1-15 RBC/hpf

What is the likely problem?

A

Acute tubulointerstitial nephritis (drug induced)

31
Q

A patient presents with type IV RTA (hyperkalemic), anemia, Na- wasting.

Urinalysis:
SG 1.012
protein +1
glucose +1 with normal serum glucose 
10-15 WBC/hpf, no bacteria

What is the likely problem?

A

Chronic tubulointerstitial nephritis

32
Q

A patient presents with recent URI.

Urinalysis shows:
SG: 1.020 
2+ protein
3+ blood 
15-20 RBC/hpf
3-5 RBC casts/hpf
0-3 WBC/hpf

What is the likely cause?

A

Acute glomerulonephritis

  • post strep
  • IgA
  • alport
33
Q

A patient presents with nephritic syndrome, hemoptysis, rapid decrease in GFR.

Urinalysis:
SG 1.020
2+ protein 
3+ blood 
15-20 RBC/hpf
3-5 RBC casts

What is the likely cause?

A

RPGN

34
Q

What is the use of plain radiographs of the abdomen (KUB)?

A
  1. kidney size/shape

2. detection of nephrolithiasis (opaque) and nephrocalcinosis

35
Q

What is ultrasonography and CT scanning used for for kidney imaging?

A
  1. size/shape
  2. urinary obstruction
  3. radiolucent stones
  4. simple vs. complex cysts
  5. PKD
  6. renal mass
36
Q

What is IV pyelogram used for in kidney imaging?

A
  1. size/shape
  2. calyceal anatomy
  3. medullary sponge kidney/papillary necrosis
  4. detection of site of obstruction
37
Q

In kidney imaging, what is the point of radionucleotide studies?

A
  1. urinary obstruction/leak
  2. renal artery stenosis
  3. renal arterial flow
38
Q

When is renal arteriography used in imaging the kidney?

A
  1. detect renal artery stenosis
  2. assess vasculitis
  3. vascular vs solid mass
39
Q

When is a voiding cystourethrogram used in kidney imaging?

A

to detect vesicouretreral reflux (VUR)

40
Q

When is retrograde/anterograde pyelography used in kidney imaging?

A

to determine sites of obstruction and to place a ureteral stent

41
Q

When is MRI used for kidney imaging?

A
  1. detect renal mass
  2. detect renal vein thrombosis
  3. screen renal vascular disease

Renal (11 decks)

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