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Flashcards in Biochemistry Deck (33):
1

What are the positive points for inulin as a measure of GFR?

Constant rate
Freely filtered at glomerulus
Not reabsorbed
Not secreted
No extra-renal eliminiation

2

Why is inulin not used?

It would need to be inputted as oral/injectible form and wait for it to be metabolised.
Hard to measure

3

What is urea?

End of product of protein metabolism

4

Where does the urea cycle occur?

in liver

5

Why is urea not suitable for eGFR ?

One quarter of elimination does not occur in kidneys

6

What will increase urea output?

Heavy protein intake

7

What is creatinine?

Product of muscle breakdown

8

Why is creatinine not a perfect marker for GFR?

Small amount is secreted by distal tubule

9

What is the normal for GFR?

120

10

What is the maximum number given for eGFR?

60.
Harder to measure in bigger numbers

11

What is the issue with using creatinine as a marker of GFR?

Not sensitive to changes in GFR until it is significantly reduced

12

What is clearance?

The volume of plasma that is cleared of a specific substance per minute

13

How is urinary creatinine clearance worked out?

[creatinine]urine X urine volume / [creatinine]serum x duration of collection

14

What factors impact on serum creatinine?

Muscle mass
Age
Sex
Diet
Ethnicity

15

If a very accurate eGFR is necessary then what is used?

Chromium- EDTA

16

What is the gold standard for measuring proteinuria?

24 hour collection
Obviously not practical

17

What test can be done relatively simply for proteinuria?

Protein:creatinine ratio

18

How much protein must be excreted/day to be significant?

Over 150mg

19

What is overflow proteinuria?

Proteinload is too much and kidney cannot reabsorb all of it.

20

When is overflow proteinuria common?

Multiple myeloma

21

What is glomerular proteinuria?

A normal amount of protein but the glomeruli do not filter it and cannot all be reabsorbed

22

What is tubular proteinuria?

Microglobulins usually go through the glomeruli but in tubular they are not reabsorbed

23

What is a key histological sign of multiple myeloma?

Eccentric nucleus.
Nucleus not in centre

24

What is multiple myeloma?

Malignancy is uncontrolled multiplication of B lymphocytes to make immunoglobulins

25

What is sometimes described on x-ray with multiple myeloma?

Pepper pot appearance in skull

26

What is microalbuminuria?

Excretion of albumin, below limits of protein detention by dipstick

27

What can microalbuinuria be a sign of?

Diabetic nephropathy

28

If hypertensive and microalbuminuria then what drug is given?

ACEI

29

What 3 classes of pathology can cause oliguria?

Pre-renal
Renal
Post renal

30

Give an example of a pre-renal issue

Reduced renal perfusion e.g. hypovolaemia

31

Give an example of a renal cause of oliguria

Intrinsic kidney damage e.g. glomerulonephritis

32

Give an example of a renal cause of oliguria

Ureteric obstruction e.g. stones or malignancy

33

What biochemical measurements are necessary to figure out the cause of oliguria?

Urine osmolality
Serum osmolality