Proximal Tubule Disturbances Flashcards
GFR L/day Gall/day Ml/min \_\_*PV
PFR
% CO
Ml/min
L/day
180
48
120
60
25
60
865
CKD
Stages
1 - over 90 2 - 60-89 3- 30-59 4 - 15-29 5- under 15
Creatinine amount in urine
More if muscular…will NOT change from day to day…might change very slowly
How to check if good collection?
Is the estimated amount of creatinine similar to the measured actual amount of creatinine
Why is sodium king?
The ATPase creates a sodium vacuum…this means cell wants to take salt back up
If anything is on either side of the membrane, you can couple their movement with sodium
What is relationship between Creatinine clearance the GFR
Overestimates
Perfect marker for GFR
Freely filtered, not screted, not reabsorbed
If filtered and secreted - overestimate GFR
If filtered and reabsorbed - underestimate the GFR
Measuring GFR with creatinie
BEcomes more accurrate if you give a competing cation that can block the secretion of the creatinine
Pitfalls of estimating GFR
Extremes of age and body size, malnutrtion and obesity, vegtarians, and dietary supplyments
NEVER use when Scr is rapidly changing
Why is BUN poor marker
Easily and totally filtered but 40-50% reabsorbed
Less in the urine than filtered…underestimates
Dependeitnt on protein intake
Increases in trauam, GI bleed or catabolism
Decreases if pt has liver dz or malnutrition
Cystatin C
Metabolized in the proximal tubules
GFR is main determinant of blood level
Maybe better and faster
URAT1 inhibitors
Competes with uric acid from the luminal side decreasing the reabsorption and increaisng uric acid excretion…penicillin will also compete
Uric acid crystals
Yellowish in color
Glucose in urine
WIll NOT appear unless plasma glucose is over 180-200…crosses maximal threshold
Significance of A1C
Average 200 - 9%…gives you a better estimate of what is going on over a period of time
