Water + Volume Disorders

Question 1

Osmolality (tonicity) =

Answer 1

Sodium

Question 2

Serum osm formula

Answer 2

2Na + glucose/18 + BUN/2.8

Or basically 2Na

270-290 (Na is half)`

Question 3

Abnormal serum [Na] (natremia) from

Answer 3

Free Water change (ADH)

HyperNa = dehydration
HypoNa = overhydration

Question 4

Abnormal Volume (ECFV) (volemia) from

Answer 4

Total body Na

Hypervolemia = UP total body Na

Hypovolemia = DOWN total body Na

Question 5

Hypovolemia

BUN/creatinine
UNa
UOsm
FENa

Answer 5

• BUN/creatinine >20:1
• UNa <20 mEq/L
• UOsm >450
• FENa =1

Question 6

Hypertonic Hyponatremia
(PseudoHypoNa)

Etiology + Tx

Answer 6

Sugar dilutes Na, makes hypertonic (water to ECS),

Tx: normal saline until hemo stable, then 1/2 saline

Question 7

Isotonic Hyponatremia

Etiology + Tx

Answer 7

Hypertriglyceridemia/hyperproteinemia
ERROR

Severe: Hypertonic saline + furosemide

Question 8

Hypotonic Hyponatremia GENERAL

Etiology

Answer 8

Kidney can’t excrete free water

Question 9

Hypotonic Hyponatremia - Hypovolemic

Etiology + Tx

Answer 9

Renal (diuretic=UNa>20)/extrarenal Na loss (UNa<10)—> release ADH —> impair free water excretion/increase thirst

Tx: normal saline

Question 10

Hypotonic Hyponatremia - Iso/Euvolemic

Etiology + Tx

Answer 10

SIADH,
hypothyroid, adrenal insufficiency, 1ry polydipsia

Tx: H20 restriction + tx cause

Question 11

Hypotonic Hyponatremia - Hypervolemic

Etiology + Tx

Answer 11

CHF, nephrotic, cirrhosis
Renal failure (high UNa)

Volume increase, pushed into interstitium (edema/ascities (splanchnic veins)) , body thinks low volume, stim RAAS/ADH/SNS

Tx: H2O+Na restriction, loop diuretic

Question 12

Hypernatremia

Etiology

Answer 12

Net water loss, no intake

Question 13

Hyponatremia

Dx

Answer 13

CNS dysfunction = cerebral edema

Lab: Serum Na<135

Question 14

Hypernatremia

Dx

Answer 14

CNS dysfunction = cerebral cell shrinkage

Lab: Serum Na >145

Question 15

Hypernatremia

Tx

Answer 15

Hypotonic fluids (oral) = water, D5W, 0.2% saline

Question 16

Hypernatremia - Hypovolemic

Etilogy

Answer 16

Renal loss (high UNa) = hyperglycemia, mannitol

Extra-renal loss (low UNa) = sweating, GI, dehydration

Question 17

Hypernatremia - Isovolemic

Etiology

Answer 17

Diabetes insipidus

Question 18

Hypernatremia - Hypervolemic

Etiology

Answer 18

Hypertonic saline

Mineralocorticoid excess

Question 19

Free water (osm)=

Answer 19

Total body fluid
Driven by plasma osmolarity, regulated by water intake/excretion

Osmolarity (concentration) changed by ADH

Question 20

ECF (volume)=

Answer 20

Total Na in body
Driven by total volume (baroreceptors),
regulated by renal Na excretion

Volume changed w/ RAAS + SNS (Ang 2, aldo, ANF)

Question 21

ADH set off by

Answer 21

Osmotic

AND SEVERE LOW VOLUME

Question 22

Ang 2 effect on glomerulus

Answer 22

• constrict efferent
• UP filtration fraction
• maintain GFR in low blood flow (more Na/H2O reabsorption)

Question 23

Sympathetic effect on renal

Answer 23

• peripheral vasoconstrict
• UP HR/contractility
• UP renin secretion
• UP renal Na absorption

Question 24

ANP/BNP effects

Answer 24

• excrete Na/H2O

* vasodilate

Question 25

ADH aquaporin channel

Answer 25

AQP - 2

Question 26

GFR effect on Na

Answer 26

Lower GFR = lower Na reabsoprtion = hyponatremia?

Question 27

Brain = hyponatremia

Answer 27

Lecture??? = edema, then K released, then shrinks (??)

Question 28

SIADH Tx

Answer 28

Acute : hypertonic saline + loop Chronic : H2O restriction, loop, UP salt intake, OR Rx (Demeclocycline, V2 antag)

Question 29

Diabetes insipidus Causes

Answer 29

Central = congenital, acquired ( post-trauma, tumor) Nephrogenic = Congenital, acquired (renal dz, hyperCa, HypoK) ALWAYS HAVE LARGE URINE VOLUME Psychogenic has low!

Question 30

Diabetes insipidus Dx

Answer 30

Water Deprivation test Increase AVP/DDAVP