Renal Function

Question 0

Biochemical testing in urinalysis

1) gross appearance
2) Microscopy
3) Biochemistry

Answer 0

1) volume and colour
2) cells, casts, crystals, bacteria
3) pH, osmolality, protein, urea, creatinine, glucose

Question 1

1) Mention 3 hormones that work on the kidney

2) Mention 3 hormones that the kidney produce

Answer 1

1) aldosterone, PTH, ADH

2) renin, erythropoietin, 1,25 dihydroxycholecalciferol

Question 2

Calcium phosphate stone may be the consequence of:

Answer 2

• Primary hyperparathyroidism

- Renal tubular acidosis

Question 3

Which kind of kidney stones are often associated with urinary tract infections?

Answer 3

Magnesium and ammonium phosphate

Question 4

Causes of proteinuria:

Answer 4

• Functional: fever, cold exposition, exercise, stress, pregnancy, orthostatic
• Not kidney origin: UTI, intercourse, prostate or uterus fluid excretion
• Not kidney pathology: circulatory insufficiency
• Pre laboratory error: penicillins, sulfonamide, contrasts

Question 5

How to assess the eGFR?

Answer 5

Measure creatinine clearance

Question 6

Why is serum creatinine concentration an insensitive index of renal function?

Answer 6

Because it may not be elevated until GFR has fallen below 50% of normal

Question 7

What do we consider when we assess tubular function?

Answer 7

Urinary and serum osmolality
Renal stones
Microglobulins beta2 alpha2

Question 8

How much of cardiac output goes to kidneys?

Answer 8

25%

Question 9

How much of renal plasma flow is filtered in glomeruli?

Answer 9

Approx. 20%

Question 10

How to measure renal blood flow?

Answer 10

PAH clearance : Htc x 100

Cannot be performed in kidney insufficiency, saline loading and anuria

Question 11

What determins the GFR?

Answer 11

• Effective filtration pressure(difference between blood pressure in the glomerular capillaries and hydrostatic pressure in the lumen and nephron)
• and the filtration coefficent(which depends mainly on filtration surface and permeability)

Question 12

Oncotic pressure in the vessels in Bowmans capsule is increased, but still filtration OUT of the vessels happen… WHY? Hmmmmm

Answer 12

Because:
Diameter of efferent arterioles are twice as small as afferent, which means there is an increase in blood (hydraulic) pressure

Question 13

What is the oncotic pressure in Bowmans Capsule?

Answer 13

Trick question! Mohahaha.. It is = 0

Cause there are no cells or proteins there

Question 14

Formula of effective filtration pressure:

Answer 14

EFP = hydraulic pressure - hydrostatic pressure in Bowmans capsule - oncotic pressure in capillaries

Question 15

What do you measure with inulin clearance?

Answer 15

GFR

Question 16

What happens to the BUN:creatinine ratio when we have pre-renal azotemia?

Answer 16

BUN»>creatinine

Question 17

Definition of proteinuria:

Answer 17

Loss of more than 300mg/24h of proteins in urine

Question 18

Which kind of proteins are lost in tubular proteinuria, and which kind in glomerular proteinuria?

Answer 18

Tubular proteinuria: low molecular weight proteins

Glomerular: high molecular weight proteins

Question 19

Tests to detect proteinuria:

Answer 19

Reagent strip test (detection limit is 200mg/L)

Quantitative analysis in laboratory(electrophoresis)

Question 20

What is normal protein loss in urine?

Answer 20

20-150mg/day

Question 21

Microalbuminuria =??

Amount of albumin in urine

Answer 21

Excretion of albumin higher than 30mg/24h

Question 22

How is the urine to plasma osmolality ratio in pre-renal and renal failure?

Answer 22

Pre renal: U osmolality : P osmolality ratio > 1,5

Renal: U:P < 1,1

Question 23

Normal osm. of urine is 50-1200 osm/L, depending on fluid intake. How to measure urine osm?

Answer 23

Freezing point. (Temp. of freezing is related to the amount of particles)

Question 24

Isosthenuria:

Answer 24

Specific gravity of urine is same as plasma (1.007-1.010) - tubules lack the ability to concentrate urine.

Question 25

Specific gravity is measured by:

Answer 25

Urinometer/refracometer

Question 26

What is FISHBERG test?

Answer 26

Measuring kidney’s ability to concentrate urine

Question 27

Tubular function test:

Answer 27

Phenolsulphonpthalein is given IV. It is not filtered, but excreted by tubular cells (94%)

Also check the amount of beta2microglobulin in serum and urine.

Question 28

High level of uric acid in blood:

Answer 28

Might be a marker of decreased GFR and tubular secretion

Question 29

Carraway method:

Answer 29

Used to measure cons. of uric acid

Question 30

Are levels of BUN in blood highest if you are hydrated or dehydrated?

Answer 30

Dehydrated

Question 31

What determines the filtered sodium load?

Answer 31

Plasma sodium cons. and GFR