Renal Function Flashcards
Biochemical testing in urinalysis
1) gross appearance
2) Microscopy
3) Biochemistry
1) volume and colour
2) cells, casts, crystals, bacteria
3) pH, osmolality, protein, urea, creatinine, glucose
1) Mention 3 hormones that work on the kidney
2) Mention 3 hormones that the kidney produce
1) aldosterone, PTH, ADH
2) renin, erythropoietin, 1,25 dihydroxycholecalciferol
Calcium phosphate stone may be the consequence of:
- Primary hyperparathyroidism
- Renal tubular acidosis
Which kind of kidney stones are often associated with urinary tract infections?
Magnesium and ammonium phosphate
Causes of proteinuria:
- 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
How to assess the eGFR?
Measure creatinine clearance
Why is serum creatinine concentration an insensitive index of renal function?
Because it may not be elevated until GFR has fallen below 50% of normal
What do we consider when we assess tubular function?
Urinary and serum osmolality
Renal stones
Microglobulins beta2 alpha2
How much of cardiac output goes to kidneys?
25%
How much of renal plasma flow is filtered in glomeruli?
Approx. 20%
How to measure renal blood flow?
PAH clearance : Htc x 100
Cannot be performed in kidney insufficiency, saline loading and anuria
What determins the GFR?
- 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)
Oncotic pressure in the vessels in Bowmans capsule is increased, but still filtration OUT of the vessels happen… WHY? Hmmmmm
Because:
Diameter of efferent arterioles are twice as small as afferent, which means there is an increase in blood (hydraulic) pressure
What is the oncotic pressure in Bowmans Capsule?
Trick question! Mohahaha.. It is = 0
Cause there are no cells or proteins there
Formula of effective filtration pressure:
EFP = hydraulic pressure - hydrostatic pressure in Bowmans capsule - oncotic pressure in capillaries
What do you measure with inulin clearance?
GFR
What happens to the BUN:creatinine ratio when we have pre-renal azotemia?
BUN»>creatinine
Definition of proteinuria:
Loss of more than 300mg/24h of proteins in urine
Which kind of proteins are lost in tubular proteinuria, and which kind in glomerular proteinuria?
Tubular proteinuria: low molecular weight proteins
Glomerular: high molecular weight proteins
Tests to detect proteinuria:
Reagent strip test (detection limit is 200mg/L)
Quantitative analysis in laboratory(electrophoresis)
What is normal protein loss in urine?
20-150mg/day
Microalbuminuria =??
Amount of albumin in urine
Excretion of albumin higher than 30mg/24h
How is the urine to plasma osmolality ratio in pre-renal and renal failure?
Pre renal: U osmolality : P osmolality ratio > 1,5
Renal: U:P < 1,1
Normal osm. of urine is 50-1200 osm/L, depending on fluid intake. How to measure urine osm?
Freezing point. (Temp. of freezing is related to the amount of particles)
