CPRS 92 93: Biochemical Investigations of Urogenital Diseases

Question 1

Urine formation was about ______ litres per day

Answer 1

1.5 litres

Question 2

Minimal urine volume is ________ mL per day

If the urine volume is lower than that, what will result?

Answer 2

400ml

Azotaemia (Elevation of blood nitrogen and creatinine)

Question 3

Glomerular Filtration Rate (GFR) are expressed in which unit?
Ideal substance for GFR measurement should be freely filtered, not reabsorbed and not secreted in renal tubules. What is the Ideal substance and what can almost achieve this effect?

Answer 3

ml/min (After the calculation, need to do conversion of units occasionally)
Ideal: Inulin
Almost: Creatinine

Question 4

What is the formula for calculation of GFR?

What is the formula for Creatinine Clearance?
(basically the same thing)

If measure creatinine clearance, what do we require in terms of urine collection?

Answer 4

(Concentration of substance in Urine x Volume of urine per unit time) / (Concentration of substance in plasma)

(Concentration of creatinine in Urine x Volume of urine per unit time) / (Concentration of creatinine in plasma)

Require 24 hour Urine Collection

Question 5

If we use creatinine to estimate the GFR, how would the result deviate from the actual result?

*Creatinine is freely filtered, not reabsorbed and slightly secreted

Answer 5

GFR will be overestimated
Creatinine will be secreted by the renal tubules into the filtrate, causing a larger concentration of creatinine in urine

Question 6

Increased GFR will lead to _______ plasma creatinine

Creatinine level in serum and Creatinine Clearance has an ______ relationship

Answer 6

Decreased plasma creatinine

Inverse relationship

Question 7

Basically, Muscularity has very high relationship with serum creatinine concentration.

Increased muscularity will lead to _________ (increased/ decreased) serum creatinine concentration

Obesity will lead to __________ serum creatinine concentration

Being black instead of asian will lead to ________ serum creatinine concentration

Adopting a vegetarian diet will lead to _______ serum creatinine concentration

Answer 7

Basically, Muscularity has very high relationship with serum creatinine concentration.

Increased muscularity will lead to increased serum creatinine concentration

Obesity will lead to unchanged serum creatinine concentration

Being black instead of asian will lead to increased serum creatinine concentration

Adopting a vegetarian diet will lead to decreased serum creatinine concentration

Question 8

Urea is filtered freely by glomeruli

Why is urea a POOR indicator of GFR?

Answer 8

Urea is filtered freely by glomeruli
Why is urea a POOR indicator of GFR?

Urea level has very strong relationship with the protein intake, fluctuates a lot.

Also, plasma urea level changes are independent of GFR.

Question 9

Which formula is best to predict GFR

Answer 9

CKD-EPI

Question 10

What might increase a person’s creatinine level by 14%?

Answer 10

Strenuous exercise

Question 11

If Cystatin C increases in urinary excretion

It is a marker for …

Answer 11

Proximal renal tubule injury or dysfunction

Question 12

In ultrafiltration, negatively charged molecules have (higher/lower) permeability?

In ultrafiltration, all common proteins are easily filtered except…

Normal daily excretion of protein is less than ____ mg, with 40-50% being ______.

Answer 12

In ultrafiltration, negatively charged molecules have lower permeability

In ultrafiltration, all common proteins are easily filtered except IgG

Normal daily excretion of protein is <150mg, with 40-50% being Albumin

Question 13

Name 2 ratios that will increase when there is proteinuria

Answer 13

Urine protein : creatinine ratio (UPCR)

Urine albumin : creatinine ratio (UACR)

Question 14

Proteinuria can be due to 3 causes:
- Glomerular
- Tubular
- Overflow
Elaborate.

Answer 14

Proteinuria can be due to 3 causes:
- Glomerular: Increase glomerular permeability
- Tubular: Proximal tubular damage that reduces tubular reabsorptive capacity
- Overflow: Increase plasma concentration of freely filtered proteins
Elaborate.

Question 15

Orthostatic proteinuria

Protein excretion varies with posture and increases with (Standing/sitting)

Answer 15

Orthostatic proteinuria

Protein excretion varies with posture and increases with standing

Question 16

To detect proteinuria, there are basically 2 methods:

• Urine dipstick test
• Sulfosalicylic acid test

Dipstick test for urine protein is most sensitive to which type of protein?

Dipstick test contains Cellulose test pad which contains Tetrabromphenol Blue and Citrate pH3 buffer. What is the colour of the pad when presence of protein, and absence of protein?

If there is proteinuria, the sulfosalicylic acid test shows (no turbidity/ flocculent precipitate)

Answer 16

To detect proteinuria, there are basically 2 methods:

• Urine dipstick test
• Sulfosalicylic acid test

Dipstick test for urine protein is most sensitive to which type of protein?- Albumin

Dipstick test contains Cellulose test pad which contains Tetrabromphenol Blue and Citrate pH3 buffer. What is the colour of the pad when absence of protein, and presence of protein?- Absent: Yellow; Present: Green
(Wong Ka Lam = Green)

If there is proteinuria, the sulfosalicylic acid test shows flocculent precipitate

Question 17

Timed urine specimen- 24 hours: All urine passed in the next 24 hours will be collected after a 1st Void of the day, which is discarded. Name a disadvantage

Answer 17

Inconvenient for patients.

Question 18

For spot urine specimen, it is the collection of urine from a single episode of passing urine.

Urine protein excretion follows a circadian pattern, which is highest in ___________.

Therefore, UACR/UPCR tests are the most accurate when performed in _________.

When you have a large muscle mass, you will have _______ creatinine in the serum. This leads to _________ (over/under estimation) of the UPCR or UACR.

When you have a small muscle mass, you will have _______ creatinine in the serum. This leads to _________ (over/under estimation) of the UPCR or UACR.

Answer 18

For spot urine specimen, it is the collection of urine from a single episode of passing urine.

Urine protein excretion follows a circadian pattern, which is highest in afternoon

Therefore, UACR/UPCR tests are the most accurate when performed in morning

When you have a large muscle mass, you will have higher creatinine in the serum. This leads to underestimation of the UPCR or UACR.

When you have a small muscle mass, you will have lower creatinine in the serum. This leads to overestimation of the UPCR or UACR.

Question 19

Albumin Excretion:
<30mg/24hr: ___________
30-299mg/24hr: ____________
>300mg/24hr: ______________

Answer 19

Albumin Excretion:
<30mg/24hr: Normal excretion
30-299mg/24hr: Microalbuminuria
>300mg/24hr: Macroalbuminuria

Question 20

Nephrotic Syndrome is a triad of…

Please use the concept of kwashiorkor to deduce

Answer 20

Heavy proteinuria
Hypoalbuminemia
Edema

Question 21

Consider Myoglobulinuria
What disease will release a large amount of myoglobin into plasma that saturates the reabsorption capcity?

What colour will be the urine for Myoglobulinuria?

Myoglobin is directly toxic to renal tubules? True or false

Answer 21

Consider Myoglobulinuria
What disease will release a large amount of myoglobin into plasma that saturates the reabsorption capcity?
Rhabdomyolysis

What colour will be the urine for Myoglobulinuria?
Red-brown in colour

Myoglobin is directly toxic to renal tubules?
True

Question 22

What is the most common 3 types of Renal Calculi/ Renal Stone? In ascending order

Uric acid is related to ________, which is a painful form of arthritis- Accumulation of uric acid crystals in joints

Answer 22

Calcium Oxalate
Calcium Phosphate
Uric Acid

Uric acid is related to gout, which is a painful form of arthritis- Accumulation of uric acid crystals in joints