4.1: Biochemistry Flashcards

1
Q

Give two markers you could use to assess the glomerular filitration rate?

A

Inulin

Creatinine

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2
Q

Describe why inulin is a good marker for GFR?

Why is it not a good marker?

A

It is freely filtered at glomerulus

It isn’t reabsorbed or secreted

It doesn’t undergo extra-renal elimination

It is difficult to measure

It isn’t endogenous

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3
Q

Describe why creatinine is a good marker for GFR?

Describe why it is not a good marker?

A

Endogenous

Easily measured

Freely filtered

Not reabsorbed

No extra-renal excretion

SMALL amount of secretion

Can only give a rough estimate of GFR

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4
Q

Match the marker to the description:

  • Inulin
  • Creatinine
    1. Rough approximation of GFR
    2. Exact value of GFR
A

Inulin = Exact value of GFR

Creatinine = Rough approximation of GFR

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5
Q

Describe creatinine when GFR is:

  • Normal?
  • Has dropped a lot?
  • Massive fall?
A

Normal GFR, Normal creatinine

When GFR has dropped a lot, creatinine rises but only a little

When there is a massive fall in GFR, there is a huge rise in creatinine

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6
Q

Define Clearance?

A

The volume of plasma that can be cleared of a substance in one minute

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7
Q

What is eGFR?

What is this based on?

A

Estimated glomerular filtration rate

Based on creatinine, age, race and sex

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8
Q

Describe the stage of chronic kidney disease based on an eGFR of..?

>90?

60-89

30-59

A

> 90 = Kidney damage with normal GFR

60-89 = Kidney damaged with decreased GFR

30-59 = Moderate kidney damage with decreased GFR

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9
Q

Describe a GFR of 15-29?

Describe a GFR of <15?

A

Severe Kidney Damage

Kidney Failure

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10
Q

What is normal GFR?

A

90-120

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11
Q

What is normal serum creatinine in

  • umol/l?
  • mg/dL?
A

50-100umol/l

0.5-1.2mg/dL

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12
Q

What is widely used to measure GFR?

A

Creatinine

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13
Q

Creatinine is better than eGFR. True or False?

A

False

eGFR is better than creatinine

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14
Q

If it is essential to get an accurate assessment of GFR, what would you use?

A

51Cr-EDTA

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15
Q

Is proteinuria normal or not?

A

Proteinuria is abnormal

Proteins are normally retained

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16
Q

What value of proteinuria suggests significant glomeruluar damage? (mg/day)

A

>150mg/day

17
Q

Describe the types of proteinuria?

  • Overflow?
  • Glomerular?
  • Tubular?
  • Secreted?
A

Overflow; Too much protein enters nephron, filtered normally, can’t all be reabsorbed - Bence Jones Proteinuria

Glomerular: Glomerulus is damaged and allows excess protein to be filtered, can’t all be reabsorbed - Albumin

Tubular: Problem with tubules prevents reabsorption

Secreted: Proteins are secreted

18
Q

Describe nephrotic syndrome?

A

Non specific kidney disease

Characterized by:

  • Proteinuria
  • Hypoalbuminaeia
  • Oedema
19
Q

Describe the physiology behind nephrotic syndrome (briefly)?

A

Loss of protein through the kidneys (proteinuria) leads to low levels of protein in the blood (hypoalbuminemia) which causes water to be drawn into soft tissues (Oedema)

20
Q

Classify these types of proteinuria if the ACR is:

<0.25?

0.25-30?

>30?

A

Less than 0.25 = Normal

0.25 - 30 = Microalbuminuria

Greater than 30 = Clinical Proteinuria

21
Q

Describe the type of proteinuria if the total protein is:

  • <0.150?
  • 0.45 - 4.49?
  • >4.50?
A

Less than 0.150 is normal

0.45-4.49 is clinical proteinuria

>4.50 is nephrotic syndrome

22
Q

What is microalbuminuria?

Testing for this can be used in the monitoring of what condition?

A

This is abnormal excretion of albumin (but it is still below the levels detected by dipstick)

Used for diabetic screening for nephropathy

23
Q

Give an example of a pre-renal, post-renal and renal cause of oliguria?

A

Pre-renal: Reduced perfusion Eg: Hypovolaemia

Post-Renal: Obstruction Eg: Stones

Renal: Intrinsic Kidney Damage eg: Glomerulonephritis

24
Q

What is oliguria?

A

Very low urine output

Between 80-400ml/day

25
Q

Describe the urine/serum osmolarity in pre-tubular failure and renal failure?

A

Pre-tubular:

Urine/serum osmolarity is >1.5:1

(Urine concentration stil occurs)

Renal
Urine/serum osmolarity is <1.1:1

(Urine concentration doesn’t occur)

26
Q

Most common type of proteinuria?

A

Glomerular