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Flashcards in CC of renal phys and disease Deck (54):
1

What is the value of Na+ in the ECW normally?

140 mEq/L (range 135-145meq/L is okay)

2

Osmolarity =

total solute/ECF volume

3

What is the normal expected urine output for a day?

1- 1.5 L/day (get about ~.5 L in total insensible loses) *this is apx = to intake of water/day)

4

The goal is to maintain isotonicity. In the case of hypertonicity-- what happens?

Stimulate hypothalmic Rs--> INCREASE thirst to increse H20 intake INCREASE ADH release to increase renal water retention

5

The goal is to maintain isotoniity. In the event of hypOtonicity, what is the body's response?

Inhibit Hypothalmic Rs Decrease thirst to decrease H20 intake Decrease ADH release --> renal water excreation

6

ADH is stimulated when plasma osmolarity is in the range of: when % blood volume loss is:

At plasma osmolarity of 290 Osm start to see sharp increase in ADH release At % blood loss of 7-10% start to see sharp increase in release of ADH

7

ADH levels are ____ in dilute urine and ______ in concentrated urine

Low High

8

Pt that drank tons of water in water contest had headache, found dead in apt later with serum Na at 114 meq/L. What happened?

Body failed to maintain isotonicity She would be HYPOtonic that should cause decreased thrist, decreased release of ADH and increased urine output.. she didn't stop drinking

9

What are signs and symptoms of Hyponatremia and when are they most common

when change in Na happens rapidly Nausea, Vomiting, Weakness, Headache, Lethargy, Seizures, Respiratory, Depression, Death

10

Example of appropriately elevated ADH: Inappropriate ADH elevation:

app: volume depletion inapp: • Cancer (eg small cell lung), CNS disease, Pulmonary disease, Drugs, Narcotics, Antiemetic, SSRIs, HIV

11

What can the following lead to: Excessive water intake • Hypotonic fluids • Other irrigants Aletered renal water hanling • Chronic kidney disease

altered water balance

12

______ is the primary determinant of ECF osmolarity

• Serum Na

13

ECF osmolarity is tightly regulated by

changes in thirst and ADH secretion

14

Excretion of a dilute urine (osm < 100 mOsm/kg) is required to prevent _______ due to increased water intake

hypoosomalarity

15

• Inappropriately elevated ADH can precipitate hyponatremia and hypoosmolarity because:

urinary dilution is impaired (osm > 300 mOsm/kg)

16

Define GFR and it's normal value

GFR: amount of plasma filtered through glomeruli per unit time (~90-125 mL/min)

17

• Nitrogenous waste product of protein metabolism • Less accurate indicator of GFR than creatinine

Blood Urea Nitrogen

18

Why is BUN less accurate then creatine as an indicator of GFR?

due to variation in: – protein intake – catabolic rate – tubular reabsorption • Useful in conjunction with creatinine in the differential diagnosis of renal disease

19

• Breakdown product of skeletal muscle • Production remains constant over time • Filtered at the glomerulus (like inulin) and can be used to estimate GFR

Serum Creatinine

20

Serum levels are______ proportionate to GFR

inversely (GFR~100/Cr)

21

Limitation of using creatine for estimate in GFR

creatinine is also secreted in the nephron and creatinine clearance overestimates GFR

22

Describe the releationship of GFR to serum creatine

serum creatine from 1 to 2 we see change in GFR = 50 ml/min

from 2 to 3; change in GFR = 25 ml/min

as serum creatine increase and kidney funx decrease, GFR decrease exponentially

23

What is the best way to measure GFR?

Renal clearance of inulin

GFR = Uinulin x V/  Pinulin

24

Assuming the following values, what is our GFR?

Pinulin = 1mg/ml

V = 1ml/min

Uinulin= 125mg/ml

 

Equation for GFR:

[Uinulin x V] / Pinulin

125mg/ml x 1ml/mg  / 1mg/ml = 125ml/min

25

What is the equaiton for measuring Creatine clearance

Creatine clearance = Ucreat x Uvol/ Pcreat

26

A pts primary care doc asks you to start pt on dialysis bc his GFR is 5 ml/min. You decide that you will IF his GFR is truly tht low. You collect a 24 hr urine sample (1440 mins) to calc Creatine clearance. Uvol = 2.1 L with Ucreat = 95mg/dl. The serum creatinine is 7.0 mg/dl and BUN is 44mg/dl

What is the pts Creatine clearance?

Creatine Clearance = Ucreat  x Uvol/ Pcreat

** you need to take into account the collection was over 24 hours or 1440 mins-->

Ucreat x Uvol/ Pcreat x 1440 mins

95mg/dl x 2100 ml 

7 mg/dl x 1440min

= 19.8 ml/min

27

When is dialysis indicated?

When pts GFR is less then 10

28

What is the Cockcroft-Gault Equation?

Creatine clearance = (140-age) x weight (kg)/ Serum Cr x 72

*if female, multiply answer by 0.85

29

Serum creatinine can be used to estimate_____:
• GFR is ~ ______
 

 

GFR

100/serum creatinine

 

30

• CrCl can be calculated by 
• CrCl can be estimated by 

U●V/P

Cockcroft-Gault

31

Serum creatinine based GFR estimates can be 
inaccurate due to extremes of 

age, BMI, or muscle mass

32

If ECF is contracted, we will cause barareceptor ______ which then cauases _____ sympathetic tone

activation

increased

33

Increased sympathetic tone d/t ECF contraction leads to:

increased renin secreation--> causes increase of Ang II--> increased aldosterone --> increased Na reabsorption to increase effective circulating volume

increased sympathetic tone directly increase tubular Na+ reabosorption. 

34

Control of tubular Na Reabsorption is controlled by a number of inputs. These will effect tubular Na channels and transporters


– Renal sympathetic tone
– Hormonal
– Blood pressure

35

What are the 2 Direct Tubular Effects to increase Na reabsorption


• Renal sympathetic nerves:Multiple tubular receptors stimulate Na reabsorption
• Angiotensin II: Tubular receptors and increases activity of proximal tubule Na/H 
countertransporter

36

Actions of Ang II in the Proixmal tubule

Increases Na reabsorption:

1. Increases Na+ in/H+ out on the lumen side

2. Increases Na+ in/K+ out on the renal IF side

3. Increases Na+/HCO3- in to the renal IF

37

Aldosterone stimulates Na reabsorption in :
– ___of filtered load of Na has its excretion 
dependent on aldosterone action

 

cortical collecting duct principal cells

~2% 

38

How does Aldosterone increase Na reabsorption?

– increases number of luminal Na channels and BL Na/K-ATPases

39

– Most important stimulus for aldosterone secretion relating to Na balance

-dependent upon renin secretion and therefore baroreceptors, macula densa, and 
renal sympathetic tone

 

Angiotensin II

40

What is the MOA of ADH on late distal tubules, CDs and collecting tubules

increases produciton and distribtuion of AQP-2 on the tubular lumen side to increaes H20 reabsorption

41

The systemic response to decreased ECF volume involves:
 

 

• Baroreceptor and sympathetic nerve activation
• Activation of Renin-AngII-Aldo system
• Increased ADH

42

These factors lead to enhanced renal tubular Na and water reabsorption
 

• Clinically reflected by low urine Na, low FENa, and elevated urine osmolarity

43

– secreted by juxtaglomerular cells
– converts angiotensinogen --> angiotensin
– angiotensin regulates BP and salt balance

 

Renin

44

Erythropoetin (epo)
– produced by _________
– stimulates erythrocyte production in ____

renal cortical tubular cells

marrow

45

formed in proximal tubule cells 
– regulates calcium and phosphate balance

• 1,25 dihydroxyvitamin D production

 

46

Increased reabsorption of Na proximal tubule, increased ADH secreation and Activation of baroreceptors are all activated when:

they sense ECF depletion

47

Increased serum _____ will contribute to hyperparathyroidism

increased serum phosphorus

48

Low Ca++ leads to increase in _____

Increased PTH

49

All of these things will be increased in response to increased PTH thats stimulated by low Ca++

Increased vit D2 activtion--> increased intestinal Ca++ reabsorption

increased renal Ca++ reabsorption

Increased Ca++ released from bones

50

Kidney disease results in _____ 1,25 Vit D prodcution and _____ serum P04

DECREASED 1,25 Vit D production

Increaed serum PO4

51

Increased serum PO4 and decreased 1,25 Vd prodution lead to what three things

decreased serum Ca++

decreased CaR

Decreased VDR

--> all leads to increased PTH

52

Chronic kidney disease: 
•Decreased_______ production leading decreased calcium absorption, hypocalcemia, and 2° hyperparathyroidism

calcitriol

53

Chronic kidney disease:

Leads to________ retention leading to 2°hyperparathyroidism

phosphorus

54

Secondary hyperparathyroidism leads to :

increased bone turnover and extraosseus calcification