Formulas and Numbers

Question 1

Na deficit

Answer 1

TBW x (Desired Na - Actual Na) (unit? -> need to convert to mmol? How is this helpful)

Question 2

Amount of Na in fluids

Answer 2

PNSS 154
D5W 0
0.45 NaCl 77
3% NaCl 513

Question 3

Serum Osm equation

Answer 3

2Na + Gluc/18 + BUN/2.8

Question 4

Osmolal gap

Answer 4

measured Osm - Computed Osm

Question 5

Osm Gap > 10

Answer 5

Toxins

Question 6

FeElectrolyte

Answer 6

UrineE x Serum Crea / UCrea x SerumE

Question 7

Free water excretion

Answer 7

(Una + UK)/Serum Na X UO (L)

Question 8

Urine Crea Normal

Answer 8

F 15-20 mkd; M 20-25 mkd

Question 9

Renal Mg wasting

Answer 9

Urine Mg > 24 g/day; FeMg 3-4%

Question 10

Renal K Wasting

Answer 10

UK> 15; UK/crea > 1.5

Question 11

Glucose in PD solution

Answer 11

1. 5%: 15-22 g
2. 5%: 24 - 40 g
3. 25%: 45 - 60 g

Question 12

steroid equivalent; 1 mg pred

Answer 12

dexa 0.2
methlypred 0.8
hydrocort 4
cortisone 5

Question 13

AG

Answer 13

Na - (Cl + Hco3)

normal 8-12

Question 14

Corrected AG

Answer 14

AG - [(4.5-Alb) x 2.5]

Question 15

UAG

Answer 15

UNa + UK - UCl

Question 16

Positive UAG

Answer 16

RTA Type 1, 4, renal failure

Question 17

Hco3 deficit

Answer 17

(Desired - Actual) x 0.5 x wt

Question 18

K deficit

Answer 18

Desired - Actual/0.27 x 100

Question 19

TTKG

Answer 19

UK x POsm/PK x UOsm

Question 20

TBW deficit

Answer 20

140-PNa/140 x TBW factor x wt

M: 0.6, F 0.5

Question 21

Compensation for Respiratory acidosis

Answer 21

Acute: Dhco3 = 0.1 (DPco2)
Chronic: Dhco3 - 0.2 (Dpco2)

Question 22

Compensation for Respiratory alkalosis

Answer 22

Acute Dhco3 = 0.2 (DPco2)

Chronic DHco3 = 0.5 (DPCo2)

Question 23

Compensation for Met Acid

Answer 23

Pco2 = 1.5(HCO3) + 8

Question 24

Compensation for Met Alk

Answer 24

Pco2 = 0.5 (HCO3)

Question 25

FeMg

Answer 25

UMg x PCrea / (0.7 x PMg x UCr)

Question 26

DAG > DHco3 or DAG/DHCO3 > 1

Answer 26

metabolic alk + HAGMA

Question 27

DAG < DHCO3 or DAG/DHCO3 < 1

Answer 27

HAGMA + NAGMA

Question 28

DAG/DHCO3 = 1

Answer 28

pure HAGMA

Question 29

DAG/DCl > 1

Answer 29

NAGMA + metalk

Question 30

DAG/DCl < 1

Answer 30

NAGMA + HAGMA

Question 31

DAG/DCL =1

Answer 31

pure NAGMA

Question 32

Crcl cockroft

Answer 32

(140-age) x wt/crea x 72

F x0.85

Question 33

Adjusted serum creatinine

Answer 33

Accounts for hemodilution iso large vol IVF that can lead to underappreciation of aki
Adjusted serum cr= SCr x [1+(cumulative fluid balance)/TBW]
Ex net pos 20L, current Scr 1.0, wt 100 kg
=1.0 x [1+ (20L )/ (0.6 x 100 kg)
=1.0 x [1 +(0.33)]
= 1.33 mg/dL