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BS V, Module III > 3. Essentials of Renal Physiology Pt. I > Flashcards

3. Essentials of Renal Physiology Pt. I Flashcards

1
Q

The Kidney is A Filter
• What kind of filter that gets rid of poisons you did not know about when you built it?
• A filter that throws ____ away and then ____ back the stuff you want

A

everything

takes

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2
Q

The Kidney is A Filter Like That
• Each kidney is made up of about one million tiny filters
• Each filter is called a ____
• Each nephron has two parts:
– A tuft of capillaries that “throws away” about a ____ of the plasma flowing through it
– A long tubule that reabsorbs about ____% of the fluid that was thrown away

• Throwing away part = tuft of capillaries surrounded by a capsule
	○ \_\_\_\_
	○ Feeds into long tubule
A

nephron
fifth
99
protourine

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3
Q

The Nephron

* Whole thing is the nephron
* Afferent arteriole goes into glomerulus
* Blood is under \_\_\_\_ here
* Fifth of plasma squeezed into \_\_\_\_
* Remainder of blood comes out the \_\_\_\_ arteriole
* Protourine travels along long tube that resorbs majority of what got filtered in the first place
* Energetic, \_\_\_\_ way of doing things; so MUST be worth it
A

high pressure
BC
efferent
inefficient

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4
Q

The Tubule

• No need to memorize
• Tubule is not \_\_\_\_ along its length
	○ Very different machinery that resorbs different things
A

uniform

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5
Q

Summary Schematic

• Glomerulus
	○ Aff arteriole in and eff arteriole going out
• \_\_\_\_ occurring at (1)
	○ Fifth of aqueous portion of blood is being squeezed out
• Travels along the tube > sig amount of reabsorption
• Eff arteriole stays next to tubule and turns into \_\_\_\_ that envelopes the tubule, and all \_\_\_\_ goes in here
• Not all of ridding of toxin is during filtration; some things are thrown away on purpose > \_\_\_\_ secretion (little arrow along the capillaries); pumping from PT cap into the tubule
• Net effect of filtration minus \_\_\_\_ plus \_\_\_\_ (PT cap) = excretion
	○ Each term is different
A 
filtration
peritubular capillaries
reabsorption
active
reabsorption
active secretion
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6
Q

GFR is the Major Measure of Kidney Function

• Glomerular Filtration Rate (GFR):
– Volume squeezed through the glomerulus per minute
– About ____ml/min in a “normal-sized” adult
– ____ liters per day

• Major metric of kidney function
	○ Measure of whether the kidney is working well
• Time is minute
• 180 is many multiples of the amount of fluid in the body
A

125

180

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7
Q

GFR is the Major Measure of Kidney Function

• Decreased GFR is evidence of ____

A

kidney disease

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8
Q

Other Evidence of Kidney Disease
• Remember when I said that the
glomerulus throws “everything” away?
• Not quite true

• Glomerulus doesn't throw everything away
• Protourine doesn't look like \_\_\_\_
	○ Barrier that prevents things from leaving
		§ No \_\_\_\_ (RBC, platelets, etc.)
		§ \_\_\_\_ (albumin) are too big to pass through filtration space
A

blood
cells
large protein

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9
Q

Other Evidence of Kidney Disease
• Healthy glomeruli prevent certain things from being filtered
– ____
– ____
– If these are in the urine, then kidney disease may be present even with ____ GFR

• In disease, they are present in the urine
• Diabetic kidney disease
	○ Glomerulus is damaged > protein in urine
	○ Most frequent example
• \_\_\_\_ disease
	○ Immune attacks kidney > red cells can get in the urine
		§ From only the glomerulus > concerning for AI disease
• If GFR is normal, but you have RBC from \_\_\_\_ origin or protein > concerning for kidney disease
A

red blood cells
protein (albumin)
normal

immune-mediated
glomerular

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10
Q 
How To Measure GFR?
• Substance that:
 – Is \_\_\_\_
– Not \_\_\_\_
– Not \_\_\_\_
• Got in urine via filtration, and didn't leave and nothing added
A

filtered
reabsorbed
secreted

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11
Q

How To Measure GFR?
• Then measure:
– ____ in the blood
– The ____ it is excreted

• Can then figure out the GFR
A

concentration

rate

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12
Q

How To Measure GFR?

• Substances that are: 
– Filtered
– Not reabsorbed 
– Not secreted
• No \_\_\_\_ produced by the body have these perfect qualities
• No natural substances that produce these qualities
	○ No metric of GFR in our own \_\_\_\_
A

substances

bodies

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13
Q

How To Measure GFR?

• Artificial Substances:
– \_\_\_\_
– \_\_\_\_
– \_\_\_\_
• Need to be \_\_\_\_
• Not \_\_\_\_
• Only used in \_\_\_\_
• Inulin is most classic one
• Iothalamate and iohexol > \_\_\_\_ substances
• Not practical in clinical setting
	○ Need a reason to inject something into somebody
A 
inulin
iothalamate
iohexol
injected
practical
research
CT scan contrast
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14
Q 
How To Measure GFR?
• Endogenous Substance: Creatinine
– Made by \_\_\_\_
– \_\_\_\_
– Not \_\_\_\_
– BUT, does have some \_\_\_\_
• About \_\_\_\_%
• (This is variable)
A 
muscle
filtered
reabsorbed
secretion
20
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15
Q

How To Measure GFR?
• In the past, kidney function was often estimated just by looking at serum levels of creatinine
• Serum level of creatinine will ____ if GFR drops

• Certain cxn of creatine in blood, and kidney is removing > something happens that decrease how much you're removing > so now the creatine will increase in blood
A

rise

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16
Q

Theoretical Curve

* Normal GFR of \_\_\_\_ with a normal creatine
* If GFR halves > the creatine will \_\_\_\_
A

100

double

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17
Q

Issues with Creatinine
• It’s Made By Muscle
• People with more muscle produce more ____ in day
• Creatinine of ____ mg/dl may be normal for some

* Same creatine in two different people an mean two different things
* 1.5 is moderately abnormal; may not be abnormal for someone who has a lot of \_\_\_\_
A

creatinine
1.5
muscle mass

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18
Q

Issues with Creatinine
• But not others

• 1.5 would be \_\_\_\_ for someone with not as much muscle mass
A

abnormal

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19
Q

Issues with Creatinine

  • This problem can be solved by collecting urine for ____ hours
  • This allows the amount of creatinine produced to be measured
  • ____ concentration is also measured
  • Volume of plasma that has been “cleared” of creatinine can then be calculated• Once creatine level is ____ > you test the levels > will account for muscle mass
A

24
plasma creatinine
steady state

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20
Q

Creatinine Clearance Equation

• Assume that all creatinine is removed by ____, then:
– GFR = [____]/SCr
– This assumption is imperfect, since some creatinine is removed by ____
• 24-hour urine collection is ____ – It is used clinicaly, but rarely

• Easy way to mess up: what to do with urine in the morning
	○ Will get incorrect result
	○ 8 hours of sleep > first time you pee > 1/3 of creatinine excretion done in the day
	○ Get up in morning > empty bladder don't \_\_\_\_ that; save everything until next day, and make sure save urine from morning void from that \_\_\_\_ and when they're done and they bring it in
	○ If you collect both mornings > \_\_\_\_ hours collection
	○ If didn't collect either > \_\_\_\_ hour collection
	○ And assume you collected over 24 hours > everything will be off
A

GFR
UCr x V
secretion
impractical

save
32
16

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21
Q

Next Step
• Can kidney function be estimated from blood tests alone?
The problem here is creatinine generation and the fact that it is not the ____ between different
people. Bodybuilders will have different levels than a 90yo person.
Is there another way to measure this beside the 24 hour collection?

A

same

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22
Q 
Cockcroft-Gault Equation
• Oldest equation
• In 249 patients, measured:
1. \_\_\_\_-hour urine creatinine excretion 
2. \_\_\_\_ level
• Used \_\_\_\_ regression to derive:

CCr (mL/min) = (140-age) x weight (kg) / Cr (mg/dL) x 72

• Doesn't measure GFR, but \_\_\_\_ excretion
• 249 patients is not a lot using a linear regression
	○ Linear regression - forcing a line over a cloud of dots
	○ Body really works like a \_\_\_\_; linear will never do it perfectly bc forcing into a line
• Measured serum creatinine level as well
	○ Way to estimate actual creatinine clearance from this?
• Not \_\_\_\_ truth
A 
24
serum creatinine
creatinine
curve
mathematical
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23
Q

Cockcroft-Gault Equation

CCr (mL/min) = (140-age) x weight (kg) / Cr (mg/dL) x 72

• Multiple the above by ____ for women

• Additional factor for women
• What is the added information here?
	○ How \_\_\_\_ you are, how \_\_\_\_ you are, and whether or not you're a \_\_\_\_
	○ Can add several other factors about human beings; but what are we trying to get at > all related to \_\_\_\_
	○ Gives a sense of how to fail:
		§ Every single 30 y/o of a given weight have less muscle mass than a male? \_\_\_\_!
		§ Is everyone who is age 50 of a given weight and gender the same? \_\_\_\_!
A 
0.85
old
weight
woman
muscle mass
no
no
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24
Q

Cockcroft-Gault Equation
• Because it’s the ____ equation, is used for many ____ guidelines
• ____ used clinically because of many limitations:
– It’s not 1976
• Body weight today is more likely to come from ____
• Laboratory creatinine assays have ____
• Because of this it tends to ____ creatinine clearance
– Weight can be surprisingly ____ to get

• Can be difficult to weigh someone than to get their blood drawn
	○ Stand them up, out of bed, roll scale into room
	○ Different scales get different results
	○ Data that is often missing - people don't enjoy seeing their weight
A

oldest
drug dosing
rarely

fat
changed
over-estimate
difficult

25
Q

MDRD Equation

• Modification of Diet in Renal Disease Study was an RCT in which subjects had:
– GFR measured by ____ clearance
– v measured
– Many other lab data as well
• Used to derive the “MDRD equation”
– Simplified form of this equation is the ____ clinical tool for estimated GFR today

• Mot frequently used equation
• Purpose of study > not designed to create this equation
	○ Looking at low protein diets and whether prevented progression of chronic kidney disease
	○ Derived equation form data set
	○ Initially a complicated one > then made a simple one
A

iothalamate
serum creatinine
dominant

26
Q

GFR = 175 x Screat-1.154 x age-0.203 x 1.212 [if black] x 0.742 [if female]

  • Needs a ____
  • Data ____ to obtain
  • What happened to body weight though?
  • Output of the equation is ml/min/1.73m2 Body Surface Area
  • Body Surface Area (BSA) is calculated by ____ and ____• CG can be done on a piece of paper; for this a person will need a calculator/computer
    ○ In setting of research, or via EMRs
    • All you need: ____, whether they’re ____and ____
    • Weight made it part of the ____
    • Output of equation isn’t just clearance; but clearance per ____ (1.73m^2 is normal - arrive here via height and weight together)
    ○ Problem: data about human being and have creatinine, and to figure out how much filtering (muscle mass); adding information is age, whether you’re black and whether you’re female
    § Imperfection - being black, is not that much data; and same about woman
    § Will all different ____
    ○ Equation performs ____ because of these inconsistencies
A

calculator/computer
easy
weight
height

age
black
female
unit
body surface area
muscle masses
poorly
27
Q

MDRD eGFR Co-incided with New Definition of ____

	• Estimated GFR became definiton of CKD
		○ Stage I:
			§ Kidney \_\_\_\_, but GFR within normal range (>\_\_\_\_)
		○ Stage II:
			§ Kidney damage with \_\_\_\_ decrease
		○ Stage III:
			§ \_\_\_\_ decrease
		○ IV:
			§ \_\_\_\_
		○ Kidney failure
			§ GFR
A 
damage
90
mild
moderate
severe
15
28
Q

Limitations of MDRD

• Derived from a population with average GFR ____ ml/min/1.73m2
– Few patients with ____ GFR
• Tends to ____ GFR in patients with true GFR>____ ml/min/1.73m2

• People in the MDRD all have CKD
	○ The average true GFR was 40
• First question: who did they study?
• Equation performs poorly for people with \_\_\_\_ > gives them one that is lower than their true GFR
A

40
normal/near normal
under-estimate
60

mild/GFR

29
Q

eGFR Alone Can Only Define CKD if < 60 ml/min/1.73m2

• Only GFR, and no protein/imaging issues; the earliest you can truly diagnose is \_\_\_\_
	○ Bc \_\_\_\_ GFR so frequently
• Stage II > so frequent underestimation > need to find other things wrong: \_\_\_\_ in urine (glomerular), protein in urine, or \_\_\_\_ showing you're missing one or structural damage (cysts, etc.)
• Issue communicating with patients
	○ Referred and don't have other problems > stage III
		§ Why didn't get \_\_\_\_ earlier? Did doc miss? Just an issue with the above
A 
stage III
under-estimated
blood
imaging
detected
30
Q

For Stage 1 or 2, Additional Evidence of CKD is needed
• ____
• ____
• Abnormal Kidneys on ____

A

proteinuria
hematuria
imaging

31
Q

Summary
• Glomerular Filtration is the Major Metric of Kidney Function
• Estimation of GFR is helpful with:
– ____ of medications
– Assessment of ____ of disease
– Decisions about ____
• Regulation of ____ is critical to maintenance of homeostasis (this will be the next talk)

A

dosing
severity
therapy
tubular reabsorption

32
Q

Two important parameters

  • ____
  • ____
A

effective vasc vol

tonicity

33
Q

Effective Vascular Volume

ECF vol&raquo_space; Plasma vol&raquo_space;
SVR&raquo_space;
CO&raquo_space;

Effective vascular volume

• EFV
	○ How well loaded the \_\_\_\_ is
	○ Not a volume > an idea of how well \_\_\_\_ your vital organs are
	○ If low > not sending enough blood to the vital organs in the proportion they need
• Plasma volume
	○ How much \_\_\_\_ you have
• SVR
	○ How \_\_\_\_ your BV are
• CO
	○ How well the \_\_\_\_ is working
• The part the kidney controls is the \_\_\_\_ through control of ECF
A 
arterial space
perfused
blood volume
dilated/constricted
kidney
plasma volume
34
Q

Body Fluid Compartments

Total body water (TBW):

ECF (____)
- ____

ICF (____)
- ____

• TBW
	○ Makes up \_\_\_\_% of body weight is split into:
		§ ECF
			□ 1/3 of TBW
		§ ICF
			□ 2/3 of TBW
		§ Black line separating > every cell membrane in body
			□ One ubiquitous protein in every membrane: \_\_\_\_
			□ As a result of this pump: Na+ in the ECF, and K+ in the ICF
A

Na+
1/3

K+
2/3

50-70
Na-K ATPase

35
Q

ECF Volume is the Major Determinant of Plasma Volume

ECF:
Plasma (____)
Interstitial fluid (____)

	• Take ECF and breaks up further:
		○ Plasma volume
			§ 1/4 of the ECF
			§ \_\_\_\_ to blood volume
		○ Interstitial fluid
			§ 3/4 of the ECF
A

1/4
3/4
major contributor

36
Q

Body Fluid Spaces:
Water makes up 50-70% of total body weight Total body water (TBW):
– ____ intracellular fluid (ICF)
– ____ extracellular fluid (ECF) compartment
• ____ Plasma and ____ Interstitial Fluid

70 kg man
TBW = 70 x 0.6 = 42 L ICF = 42 x 2/3 = 28 L
ECF = 42 x 1/3 = 14 L Plasma =14x1/4=3.5L

• Plasma volume makes up \_\_\_\_ of the TBW
	○ Keeps you alive
	○ If not high enough > heart wont be able to pump sufficient blood to the organs
• What's IF then of TBW?
A 
2/3
1/3
1/4
3/4
1/12
37
Q

Definitions: Osmolality and Tonicity:
• Osmolality = ratio of ____r
– Calculated Osmolality = 2 x [Na+] + Glu/18 + Urea/2.8 – Normally = 2x(140) + 100/18 + 10/2.8≈____ mOsm
– Osmolality can be directly measured by the ____

• Particles in water > has an osmolality
	○ Important for osmotic shift
	○ Large number of particles > traps \_\_\_\_
		§ Why starch exist > 20 glucoses, each is one particle > then link and make starch > one whole particle and store without the cell \_\_\_\_
• Take all the particles in serum that we measure > can calculate the osmolality
	○ Euro's wouldn't need the divisions
	○ Normal serum value: 140; normal glucose: 100; and a normal urea: 10 > 290 is a normal serum osmolality
	○ Can \_\_\_\_, AND measure by the \_\_\_\_
A

particles/water
290
lab

water
shrinking
calculate
lab

38
Q

Tonicity

• Tonically active osmoles are confined to one side of cell membrane or the other
• Also called “effective osmoles”
• Examples:
– Effective osmoles: ____, K, ____, Mannitol
– Ineffective osmoles: ____, Ethanol
– Glucose can behave as either effective or ineffective (depending on ____)
• Tonicity can NOT be directly measured by the ____

• TA osmoles have two properties
	○ Osmotically \_\_\_\_
	○ Confined to one side of \_\_\_\_ or the other
• Cl-
	○ Anion of Na+
	○ Largely \_\_\_\_
• Mannitol
	○ Artificial
	○ Doesn't go into \_\_\_\_
	○ Used to suck fluid \_\_\_\_ of cells
• Urea and ethanol distribute across the entire TBW
• Glucose
	○ Can behave as either depending on insulin
	○ Tehcnically: \_\_\_\_, usually outsdie of cells
		§ But in presence of insulin > pumps into cells > metabolized or changed into a starch
• Tonicity CANNOT be directly measrued by lab; but you can do it for the \_\_\_\_
	○ Tonicity; have to see if cells \_\_\_\_ or swole
	○ No \_\_\_\_ term! (unlike osmolality)
A 
Na
Cl
urea
insulin
lab

active
membrane

EC

cells
out

effective
osmolality
shrunk

urea

39
Q

Tonicity
• Since it cannot be measured, “best guess” is to calculated it:
• Calculated Tonicity= 2 x [Na+] + Glu/18
• This is the same as the calculated osmolality, except that the ____ term is removed

• Na+ is always partnered with something that is also tonically \_\_\_\_
	○ Double it
	○ And then take glucose and divide by 18
		§ Because of unit to turn it into the same units as we have for the sodium
A

urea

active

40
Q

Why do we care about Tonicity?
Tonicity Dictates ____

K+ restricted to ____ and Na restricted to ____
• Water moves across ICF and ECF to maintain equal ____ across both compartments

• Water is moving in and out of cells to maintain \_\_\_\_ tonicity
• Add tonically active osmole outside that cannot get into the cell
	○ Like NaCl, and raise it > H2O will move inside to \_\_\_\_ in order (down it's own gradient) > shrink cell until cxn of \_\_\_\_ matches the cxn of Na+ outside
	○ Tonicity: changes cause fluid shifts across membranes > cause shrink/swell > changes in \_\_\_\_
A 
water distribution
ICF
ECF
tonicity
equal
out
K+
cell size
41
Q

Why do we care about Tonicity?

	• Add RBC into isotonic > looks \_\_\_\_
• Add into salt but hypotonic (not as high as isotonic) > water will go into cells > \_\_\_\_
• Add cells into solution that is hypertonic > water drawn out of cells > \_\_\_\_ up
• Take RBC and drop into pure H2O > swell and explode > won't see any RBC > \_\_\_\_
• Disorder in tonicity (systemic) > never causes a problem in \_\_\_\_ function
	○ Another organ will undergo changes that are lethal before the RBC gets messed up; the only organ that's entirely surrounded by bone > the \_\_\_\_
		§ Isotonic: nice \_\_\_\_
		§ Equivalent of swollen RBC > swell your brain > no sulci and get \_\_\_\_ of your brain outside the foramen magnum
		§ Shrink brain > tear dura > \_\_\_\_
A 
same
swell
shrivel
hemolysis
RBC
brain

sulci
herniation
subdural hematoma

42
Q

Basic physiology

• Tonicity
○ Regulate via is not via salt bc it would have big impacts on volume
§ Via ____
□ Has some impact on volume
□ Impact tonicity bc by def is by number of tonically active osmoms divided by water
§ Tonicity detected by ____ > two nuclei control thirst and ADH release
□ ADH
® Hormone released by post pit acts on kidney and tells to hang onto ____
® If off > urine volume will increase and it will be ____
§ ADH and thirst impact water balance
□ V thirsty and high ADH > will hang onto ____
□ ADH switched off, and thirst switched off > pee out a lot of ____
• Two circles are separate, but one can perturb the other
○ Tonicity circle decides that you’re ____, and says you need water (upreg water and ADH)
§ 1/3 of water goes into ECF (not great vol exapnder); if at this time, you’re at upper limit of what ECF circle thinks you’re at ____
□ As soon as extra water pushes you over limit > downregulat RAT > pee out ____ rich urine
○ Separate unless body has to choose which one is more important
§ Body in this situation; will always choose ____ over anything else
§ Significant intravascular volume depletion (>10%) > body will forget tonicity, hangs onto ____ no matter what > hang onto ADH and maybe thirst > try to retain water even though not a great volume expander (better than nothing) > so desperate, get whatever I can get
• Underpins thigns that are important:
○ Way the body works
○ Way we intervene when we need to change something (in problems of ECF volume and tonicity)
§ Importatn in disorders of tonicity

A 
water
hypothalamus
water
dilute
water
water
hypertonic
hypervolemia
salt
ECF volume
water
43
Q

Basic physiology

• Tonicity
○ Regulate via is not via salt bc it would have big impacts on volume
§ Via ____
□ Has some impact on volume
□ Impact tonicity bc by def is by number of tonically active osmoms divided by water
§ Tonicity detected by ____ > two nuclei control thirst and ADH release
□ ADH
® Hormone released by post pit acts on kidney and tells to hang onto ____
® If off > urine volume will increase and it will be ____
§ ADH and thirst impact water balance
□ V thirsty and high ADH > will hang onto ____
□ ADH switched off, and thirst switched off > pee out a lot of ____
• Two circles are separate, but one can perturb the other
○ Tonicity circle decides that you’re ____, and says you need water (upreg water and ADH)
§ 1/3 of water goes into ECF (not great vol exapnder); if at this time, you’re at upper limit of what ECF circle thinks you’re at ____
□ As soon as extra water pushes you over limit > downregulat RAT > pee out ____ rich urine
○ Separate unless body has to choose which one is more important
§ Body in this situation; will always choose ____ over anything else
§ Significant intravascular volume depletion (>10%) > body will forget tonicity, hangs onto ____ no matter what > hang onto ADH and maybe thirst > try to retain water even though not a great volume expander (better than nothing) > so desperate, get whatever I can get
• Underpins thigns that are important:
○ Way the body works
○ Way we intervene when we need to change something (in problems of ECF volume and tonicity)
§ Importatn in disorders of tonicity

A 
water
hypothalamus
water
dilute
water
water
hypertonic
hypervolemia
salt
ECF volume
water
44
Q

ECF Volume: Na Content

• Na is restricted to ____ compartment
• Na is the major osmole in ECF compartment
• Total body Na content determines ____
• Stable hemodynamics is dependent on ____
Stable ECF volume is maintained by Na balance ____ (dietary) = ____ (renal and extrarenal)
– ____ of Na is the major way of regulate Na content in body
– Extrarenal Na loss can outpace Na intake under certain conditions (diarrhea, burns, blood loss) leading to total body Na loss and abnormally low ____ (hypovolemia)

* ECF volume is equivalent to sodium content
* Most common worldwide of extrarenal Na loss: \_\_\_\_
A 
ECF compartment
ECF volume
stable ECF volume
intake
output
renal excretion
ECF volume

diarrhea

45
Q

How Do We Evaluate Volume and Tonicity?

• Effective vascular volume:
– Labs for this are \_\_\_\_
– This is a \_\_\_\_ evaluation 
• History
• Physical Exam
– \_\_\_\_, Lung Exam for Crackles, \_\_\_\_, Acute Change In Weight, \_\_\_\_.

• Tonicity:
– Clinical exam for this is ____
– This is a ____ evaluation
• Serum sodium and ____

• Clinical decision
	○ Pattern that requires more than one piece of information, and requires seeing and examining the patient
	○ Impossible - need to recognize a pattern of things to recognize one "animal" from another
	○ Volume status - need a lot of things to determine
	○ History
		§ Puking and a lot of diarrhea
			□ Hypovolemia
	○ Physical exams
		§ Crackles - fluid in the \_\_\_\_; and may be volume overload
		§ Peripheral edema
			□ Normal tissue should spring back out; but edematous feels like \_\_\_\_
		§ Very helpful: \_\_\_\_ change in weight
			□ Weigh patients daily
			□ Change weight by 2 kg > likely to be from \_\_\_\_
		§ Most specific finding: loss of \_\_\_\_
			□ Someone's armpit > small amount of sweat; no sweat > \_\_\_\_
			□ Can have ax sweat and can still be volume depleted; very \_\_\_\_ but not very \_\_\_\_
				® Ninja analogy
• Tonicity
	○ Clinical exam > nonspecific and unreliable
	○ Lab diagnosis!
		§ Key for this
A 
unreliable
clinical
jugular venous pressure
peripheral edema
axillary sweat

unreliable
lab
osmolality

alveoli
memory foam
acute
fluid

axillary sweat
specific
sensitive

46
Q

Serum Sodium Concentration Does Not Asses Total Body Sodium

• Chem 7:
	○ TL is sodium
	○ K below
	○ Cl next
	○ Bicarbo below
	○ BUN
	○ Creatinine below
	○ Glucose
• Cations, anions, kidney
• \_\_\_\_ is checked on daily basis on in-patients
	○ Tells you nothing about \_\_\_\_ Na+ cxn
• Effective intravascular volume is impacted by plasma volume, which in turn is impacted by \_\_\_\_, which then impacted by \_\_\_\_
• Tonicity is impacted osmolality, which is related to cxn of \_\_\_\_
• Check Na everyday; and people mistake that for how much Na in your body
	○ Cxn doesn't tell you how big the \_\_\_\_ is
A 
Na+
total body
ECF volume
total body Na
Na
volume
47
Q

Volume Disorder = Abnormal Total Body Na Content

• Normal total body Na = \_\_\_\_
• Too much Na = Volume \_\_\_\_
• Too little Na = Volume \_\_\_\_
– Not the same as \_\_\_\_
– Dehydration implies too little water for the amount of solute in the body (\_\_\_\_)
• Dehydration is diff from volume depletion
	○ Voluem depeletion > disorder in total Na+ body content
	○ Dehydration > too little water > hypernatremia/hypertonicity
A 
euvolemia
overload
depletion
dehydration
hypernatremia
48
Q

Tonicity Disorder= Abnormal Ratio of Water to Solute

• In general:
• Normal tonicity:
– Normal Serum Sodium (\_\_\_\_)
• Low tonicity:
– Too much water relative to solute 
– \_\_\_\_
• High Tonicity:
– Too little water relative to solute – \_\_\_\_
* High tonicity = dehydration
* Can substitute for hyper/hypoaqeumia
A

eunatremia
hyponatremia
hypernatremia

49
Q

Summary
ECF Volume Disorder=
Abnormalities in ____ Content

Too little sodium: Volume ____
Too much sodium: Volume ____

Osmolar Disorders= Abnormalities of ____ Balance

Too much water (relative to sodium): ____
Too little water (relative to sodium): ____

A 
total body sodium
depletion
overload
water
hyponatremia
hypernatremia
50
Q

Types of IV Fluids

• IVF used to give NaCl > ____
– Often called “normal saline”
– Tonicity is comparable to the aqueous portion of ____

• IVF used to give water >  5mg/dl \_\_\_\_
– Often called “D5W”
– Giving pure water IV would lyse \_\_\_\_s
– 5mg/dl dextrose is close to iso-osmolar initially, but the dextrose gets \_\_\_\_
• This leaves behind \_\_\_\_
• Gave pure water > drop RBC into a beaker > explode; won't have any systemic problems in RBC with regards with tonicity bc brain will die first
	○ Can have a problem \_\_\_\_ > pure water > locally RBC will explode > sterile water has a red label; but used to mix with other things; never inject by itself!
	○ Add 5 mg/dl dextrose into the water > give pure water
		§ Solution is \_\_\_\_ bc of the dextrose, and will get pumped into cells and metabolized and go away
		§ Liter of D5W distributed over entire body > slight decrement in serum sodium; won't get a sudden drop that'll cause hemolysis
• \_\_\_\_to give salt and volume expand
• \_\_\_\_ fluid to give water
A 
isotonic saline
blood
dextrose
red cells
metabolized
water

locally
isotonic
isotonic
hypotonic

51
Q

Add 1.5 Liters Normal Saline

• What happens to tonicity?
	○ Stay the \_\_\_\_
	○ Fluid is isotonic > no change in tonicity

• What happens to ECF
	○ \_\_\_\_
	○ Will icnrease by 1.5L
		§ Bc of sodium containing and isotonic > 100% of it stays in ECF volume

• What happens to ICF
	○ Stays the \_\_\_\_
	○ Unchanged!
A

same
increases
same

52
Q

New Case
• Add 420 mEq Dry NaCl:

• Tonicity
	○ Add tonically active osmom without any water > \_\_\_\_
	○ Ratio will \_\_\_\_

• ECF volume
	○ \_\_\_\_
	○ Sodium is trapped EC; sucks water from IC

• ICF volume
	○ \_\_\_\_
	○ Pulling water from inside cell
A

increase
increase
increase
decrease

53
Q

New Case
• Add 1.5 D5W:

• Tonicity
	○ \_\_\_\_
	○ Water without tonically active osmom > \_\_\_\_ the ratio (increase denominator without changing nominator)

• ECF volume
	○ Water by itself > nothing to trap it
	○ \_\_\_\_; 40% of it will stay the same

• ICF volume
	○ \_\_\_\_
	○ 2/3 or 60% of water > will go into cells
A

decrease
decreases
increase
increase

54
Q

Impact on ECF

• 1.5 L Normal Saline: 17 L > ____ L

• 1.5 L D5W: 17 L > ____ L
– But [Na] decr’d from 140mEq/L > ____ mEq/L

• 420mEq NaCl: 17 L > ____ L
– But [Na] incr’d from 140mEq/l > ____ mEq/L

	• ECF
		○ Normal saline
			§ ECF goes up 1.5L
		○ D5W
			§ Goes up .6 L
			§ But [Na] serum \_\_\_\_
		○ Dry salt
			§ Goes up .9 L
			§ But [Na] serum \_\_\_\_
A

18.5
17.6
135
17.9
145
dropped
increased

55
Q

ECF Volume ≠ ____

• In these three examples, note that extracellular volume ____ (albeit by a
different amount in each case) independently of changes in body fluid ____ (and the plasma sodium concentration).
• In fact, sodium concentration either increased, stayed the same, or decreased.

• Volume expanded all the patients; but \_\_\_\_ did different things every time
A

[Na concentration]
increased
osmolality
[Na]

56
Q

– A normal euvolemic person will ____ the salt
and water out in urine and go back to 17L

– [Na] 140mEq/L > 135 mEq/L, but:
– Normal person will pee the extra ____ out

–[Na] 140mEq/l > 145mEq/L, but:
– Normal person would drink and/or pee out the extra ____

* In the real world > the types of changes would only happen in someone without working 
* Normal kidneys > attenuated, because of peeing and drinking and maintaining homeostasis
A

pee
water
Na

kidneys

57
Q

Take Home Points:
• Body’s primary goal is to defend adequate ____
– Na handling is critical for this
• An important secondary goal is to defend ____
– Water handling is critical for this
• Water and Na Handling are typically ____
• ECF Volume ≠ [____ Concentration]

A

circulation
tonicity
independent
Na

58
Q

Final Summary

  • GFR is the major metric of ____
  • Reabsorption of Na by the kidney plays a major role in maintaining ____
  • Reabsorption of Water by the kidney plays a major role in maintaining ____ and preventing brain ____
A

kidney function
euvolemia
tonicity
swelling/shrinkage

BS V, Module III (8 decks)

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