Fluids & Lytes

Question 1

serum osmolality calculation

Answer 1

2Na + (BUN/2.8) + (glucose/18)

Question 2

normal serum osmolality

Answer 2

265-285

Question 3

formula to correct metabolic acidosis

Answer 3

mEq bicarb = wt x 0.3 x base deficit

Question 4

causes of metabolic alkalosis

Answer 4

Vomiting! – losing acid

• pyloric stenosis
• NG suction
• CF

Question 5

electrolytes in pyloric stenosis

Answer 5

hypochloremic
hypokalemic
metabolic alkalosis

• think losing HCl in emesis (therefore low Cl, and alkalosis)
• hypokalemic from contraction- absorb Na and secrete K in kidneys

Question 6

causes of normal anion gap acidosis

USED CARP

Answer 6

• decreased bicarb
• kidney dysfxn
• diarrhea ** most common
• increase Cl

USED CARP
U- ureterostomy
S- small bowel fistula
E- extra chloride
D- diarrhea
C- carbonic anhydrase inhibitor (acetazolamide)
A- adrenal insufficiency
R- RTA
P- pancreatic fistula

Question 7

type 1 RTA (7)

Answer 7

• distal collecting tubule
• unable to rid of H
• metabolic acidosis without gap
• urine pH inc >5.5
• hyperchloremic
• hypokalemic
• mimicked by spironolactone

Question 8

type 2 RTA (6)

Answer 8

• proximal tubule
• unable to reabsorb HCO3
• metabolic acidosis
• distal tubule still able to secrete H –> acidify urine
• urine pH <5.5
• mimicked by acetazolamide

Question 9

type 3 RTA

Answer 9

combination of 1 & 2

Question 10

type 4 RTA

Answer 10

• aldo resistance
• unable to resorb Na or secrete K
• hyperkalemia results

Question 11

elevated anion gap causes

Answer 11

MUDPILES
M- methanol
U- uremia
D- DKA
P- paraldehyde
I- ingestion/isoniazid/iron
L- lactic acid
E- ethanol/ethylene glycol
S- salicylates

Question 12

daily requirement for Na

Answer 12

3 mEq/kg/day

Question 13

central diabetes insipidus

Answer 13

lack of ADH

Question 14

peripheral diabetes insipidus

Answer 14

resistance of ADH

Question 15

labs in DI

Answer 15

high serum osmolality

inappropriately dilute urine

Question 16

nephrogenic DI (3)

Answer 16

• x linked (males only)
• kidney doesn’t respond to ADH
• unable to respond to exogenous vasopressin

Question 17

how to determine the type of hyponatremia

Answer 17

calculate FeNa

= (Una+Pcr)/(Ucr+Pna)

Question 18

causes of SIADH (9)

Answer 18

• head trauma/infection/brain tumor –> pituitary injury –> SIADH
• pulm d/o
• endo d/o
• chemo (vincristine, cyclophosphamide)
• AED (carbamazepine)
• post op
• guillian barre

Question 19

SIADH

• serum NA?
• serum K?
• BP?
• UOP?
• urine Na
• BUN/Cr?

Answer 19

low
nl
high
low
high
nl

Question 20

treatment for SIADH

Answer 20

fluid restriction

Question 21

what is the next step when fluid restriction does not work in SIADH? (3)

Answer 21

• furosemide (NOT thiazide as it may decrease Na more)
• hypertonic saline (give if Na less than 120)
• demeclocycline

Question 22

when to use demeclocycline for treatment of SIADH

Answer 22

when fluid restriction fails

blocks the affect of ADH on kidney
can only us in children>8 (like doxycycline)

Question 23

what does chronic diuretic therapy do to Na

Answer 23

hyponatremia

Question 24

medications that cause hyponatremia (4)

Answer 24

1- vincristine (SIADH)
2- cyclophosphamide (diminished H20 excretion)
3- chloropropramide (stimulates vasopressin)
4- thiazides (blocks renal Na and Cl resorption)

Question 25

with dilutional hyponatremia what is the total body sodium

Answer 25

normal dilutional hyponatremia in serum d/t water intoxication urine Na increased

Question 26

affect of hyponatremic dehydration on brain

Answer 26

pontine damage

Question 27

urine sodium in dilutional hyponatremia

Answer 27

high

Question 28

urine sodium in 3rd spacing

Answer 28

low

Question 29

daily requirement for K

Answer 29

2 meq/kg/d

Question 30

sx of hypokalemia (6)

Answer 30

``` muscle pain weakness paralysis constipation ileus polyuria ```

Question 31

EKG changes in hypokalemia (3)

Answer 31

T wave flattening --> U wave ST depression PVC

Question 32

potassium replacement in hypokalemia

Answer 32

KCl 0.5-1 meg/L per kg over an h (max 40)

Question 33

hypocalcemia EKG changes

Answer 33

QT prolongation

Question 34

hypomagnesium EKGchanges

Answer 34

prolonged PR and QT intervals

Question 35

hypoglycemia EKG changes

Answer 35

none

Question 36

hyponatremia EKG changes

Answer 36

none

Question 37

hypernatremia EKG changes

Answer 37

peaked T wave | with worsening sx have widened QRS and absence of P waves

Question 38

treatment of hyperkalemia (6)

Answer 38

- calcium chloride IV - insulin (+glucose) - bicarb - albuterol - furosemide - kayexelate (oral polystyrene resin)

Question 39

sodium concentration in oral rehydration fluid

Answer 39

75 mEq/L

Question 40

rate of oral rehydration fluid with moderate-severe dehydration

Answer 40

50 cc/kg over 1-4 hrs 10 kg baby = 500 cc (or 16 oz) = 4 oz/h

Question 41

labs in CF

Answer 41

hypochloremic hyponatremic metabolic alkalosis with dehydration Lose NaCl in sweat then have contraction alkalosis

Question 42

skin findings in hypernatremia

Answer 42

doughy skin