Biochemical measures in renal disease

Question 1

What are the properties of a good marker of GFR?

Answer 1

Freely filtered but not reabsorbed nor secreted

Question 2

Urea is the end product of what?

Answer 2

Protein metabolism

Question 3

Where does the urea cycle occur?

Answer 3

Within the liver

Question 4

What biochemical marker is commonly used to assess GFR?

Answer 4

Creatinine

Question 5

Creatinine is the end product of what?

Answer 5

Muscle protein metabolism

Question 6

What is the drawback of using creatinine as a biochemical marker?

Answer 6

Not sensitive to changes in GFR (60-120) unless they are marked (

Question 7

How can small changes in GFR be detected?

Answer 7

Urinary creatinine clearance

Question 8

Which clinically significant factors will affect GFR? How are these estimated?

Answer 8

Muscle mass and diet

Estimated from age, ethnicity and sex

Question 9

Define clearance

Answer 9

Volume of plasma cleared of a substance per minute

Question 10

State the equation used to calculate urinary creatinine clearance

Answer 10

(Urine creatinine conc x urinary output) / (Serum creatinine conc x duration of collection)

Question 11

Is creatinine concentration higher in urine or serum? Why is this relevant for carrying out calculations?

Answer 11

Urine

Must remember to make units the same

Question 12

Which factors are considered in the equation used to calculate eGFR?

Answer 12

Serum creatinine
Age
Sex
Ethnicity

Question 13

How is chronic kidney disease classified based on eGFR?

Answer 13

1 (kidney damage with normal/high GFR) - >90
2 (kidney damage with mildly low GFR) - 60-89
3 (moderately low GFR) - 30-59
4 (severely low GFR) - 15-29
5 (kidney failure) -

Question 14

How are each of the chronic kidney disease classifications managed?

Answer 14

1 - treatment of co-morbid, risk reduction
2 - estimate progression
3 - evaluating and treating complications
4 - preparation for kidney replacement therapy
5 - replacement

Question 15

The functionality of which part of the nephron is being assessed with GFR?

Answer 15

Glomerulus

Question 16

Plasma proteins are normally found in the urine. T/F

Answer 16

False

Question 17

How can proteinuria be measured?

Answer 17

24 hour collection

Protein:creatinine ratio (avoids errors due to dehydration status)

Question 18

Significant glomerular damage is indicated by proteinuria over which level?

Answer 18

> 150mg/day

Question 19

List the different types of proteinuria?

Answer 19

Overflow (bence jones)
Glomerular (albuminuria)
Tubular (microglobulinuria)
Secreted (tamm-horsfall)

Question 20

Describe overflow proteinuria

Answer 20

An increase in serum protein to the level that the mechanisms of reabsorption within the tubules reach transport maximum and thus cannot reabsorb all protein

Question 21

Describe glomerular proteinuria

Answer 21

Protein levels are normal but glomerular damage allows all proteins to be filtered thus overwhelming mechanisms of reabsorption within the tubules meaning that it can’t all be reabsorbed

Question 22

What is multiple myeloma? Which type of proteinuria does it cause?

Answer 22

Malignancy of the plasma cells which causes overproduction of antibodies and light chain proteins resulting in overflow proteinuria

Question 23

What is the characteristic appearance of the skull in multiple myeloma?

Answer 23

Pepper pot

Question 24

How is multiple myeloma diagnosed?

Answer 24

Bone marrow aspirate & analysis
Protein electrophoresis
Skeletal survey

Question 25

What is nephrotic syndrome? Which type of proteinuria does it cause?

Answer 25

Non-specific kidney disorder characterised by large proteinuria, hypoalbuminaemia and oedema. Glomerular

Question 26

Why does oedema occur in nephrotic syndrome?

Answer 26

Loss of protein in the urine causes hypoalbuminaemia and thus alters oncotic pressures. The reduced oncotic pressure means more fluid is left within the interstitium (i.e oedema)

Question 27

What is microalbuminuria?

Answer 27

Excretion of albumin in abnormal quantities but still below the level of detection by dipstick testing

Question 28

Microalbuminuria is the earliest sign of which complication of which disease? How is it treated?

Answer 28

Diabetic nephropathy

ACE inhibitors

Question 29

Describe the sliding scale of proteinuria from least protein to most protein

Answer 29

Microalbuminuria
Proteinuria
Nephrotic

Question 30

How can proteinuria be detected?

Answer 30

Dipstick
PCR (protein creatinine ratio)
Total protein
ACR (albumin creatinine ratio)

Question 31

Tubular function problems can be divided into three categories. Name them and there common causes

Answer 31

Pre-renal - reduced kindey perfusion (blood loss)
Renal - intrinsic damage (glomerulonephritis, toxins)
Post-renal - obstruction (stones, malignancy)

Question 32

What is oliguria?

Answer 32

Peeing an abnormally small amount

Question 33

What is a normal serum osmolarity?

Answer 33

270-300

Question 34

Should urinary or serum osmolarity be higher?

Answer 34

Urinary - if they are equal it indicates tubular damage

Question 35

Are the kidney tubules working in pre-renal or renal failure?

Answer 35

Tubules are working in pre-renal failure

Question 36

Which biochemical results would indicate intrinsic renal damage?

Answer 36

High sodium
Low urine:serum urea
Low urine:serum osmolarity