Week 4 - G - Bicohemical measurements in renal disease

Question 1

What is the juxtaglomerular apparatus?

Answer 1

It is a specialized structure formed by the distal convoluted tubule and the afferent arterial

Question 2

What are the three cells of the juxtaglomerular apparatus?

Answer 2

Granular (juxtaglomerular) cells Macula densa Extraglomerular mesangial cells (lacis cells)

Question 3

What is the function of the macula densa cells? What does it do if NaCL is low?

Answer 3

The macula densa is sensitive to the sodium chloride concentration in the distal convoluted tubule If NaCl is low in the DCT, it releases vasoactive mediators to dilate the afferent arteriole which increases the GFR It also increases renin release from the granular cells

Question 4

What is the ideal GFR marker?

Answer 4

An endogenous substance, freely filtered which does not undergo tubular modification and does not undergo extra renal elimination and is easy to measure

Question 5

What is the ideal marker for measuring GFR? However it is exogenous and not easy to measure

Answer 5

This would be inulin

Question 6

What is used to measure the estimated glomerular filtration rate?

Answer 6

Creatinine

Question 7

What is creatinine a by product off?

Answer 7

The breakdown of creatine kinase from muscle

Question 8

What is the rapid destruction of skeletal muscle resulting in leakage into the urine of the muscle protein myoglobin?

Answer 8

This is rhabdomyolysis

Question 9

What two things will be risen in rhabdomyolysis in the urine?

Answer 9

Myoglobin and creatine kinase

Question 10

Direct injury to the kidney and plugging of the filtering tubes of the kidneys by the muscle proteins are among the causes of kidney function impairment in the setting of rhabdomyolysis. What is the usual presentation of a patient with rhabdoyolysis?

Answer 10

Patinet falls and has an injury, remains lying on floor for a day and has now become hypotensive and is confused

Question 11

Why is creatinine not prefect for measuring the exact eGFR?

Answer 11

It is also secreted into the renal tubules and therefore is not perfectly accurate

Question 12

What is the volume of plasma that is theoretically cleared of a substance per minute?

Answer 12

This is the plasma clearance of a substance

Question 13

How is the plasma clearance of a substance measured?

Answer 13

It is the volume of a substance cleared per minute It is calculated by the volume of substance in the urine x the volume of urine produced per mintue divided by the concentration of substance in the plasma Clearance = [X]urine x Vurine / [X]plasma

Question 14

What is the equation that allows you to calculate the glomerular filtration rate? What are the four facotrs required?

Answer 14

MDRD4 equation Serum creatinine Age Race Sex

Question 15

What are the classification of chronic kidney disease?

Answer 15

Stage 1 - GFR > 90 with evidence of kidney damage Stage 2 - GFR >60 with evidence of kidney damage Stage 3 - GFR 30-60 Stage 4 - GFR 15-30 Stage 5 - GFR <15

Question 16

What is the prevalance of the stages of chronic kidney disease?

Answer 16

Stage 1 and 2 combined - 7% Stage 3 - 4% Stage 4 - 0.2% Stage 5 - 0.1%

Question 17

• Patient with hypertension, proteinuria, and a GFR of 78ml/min What stage is this?

Answer 17

This would be stage 2 chronic kidney disease

Question 18

• 82y/o lade with GFR of 76ml/min, normal urinalysis and a normal US scan What stage is this?

Answer 18

This lady does not have chronic kidney disease

Question 19

• Patient with polycystic kidneys (identified on US), with a GFR of 100ml/min? • Patient with scarring seen on US, caused by reflux nephropathy, and a GFR of 66ml/min – stage 2 CKD ?

Answer 19

• Patient with polycystic kidneys (identified on US), with a GFR of 100ml/min – stage 1 CKD • Patient with scarring seen on US, caused by reflux nephropathy, and a GFR of 66ml/min – stage 2 CKD

Question 20

When the GFR rate decreases, what happens to the serum creatinine?

Answer 20

The serum creatinine is greatly elevated

Question 21

At what eGF, is the actual score said to not be very accurate?

Answer 21

A glomerular filtration rate of greater than 60

Question 22

What are two ways to measure the degree of proteinuria? Proteinuria usually goes with kidney damaged as proteins are normally retained

Answer 22

24 hour urine protein Protein:creatinine - blood spot sample ratio

Question 23

What is the earliest expression of diabetic nephropathy seen on urine disptick?

Answer 23

Mircoalbuminuria

Question 24

patinet can present with oliguria due to pre-renal, renal and post-renal problems Give examples of why?

Answer 24

Pre renal - renal hypoperfusion, due to hypovalemia, blood loss, haemorrhage Renal - intrinsic damage - e actute tubular necoriss, glomerulonephritis, nephrotoxins Post renal - obstruction eg ureteric stones or tumour

Question 25

is the kidney an endocrine or exocrine organ?

Answer 25

The kidneys are endocrine organs