Correction Made Easy By Adrian Paul J. Rabe, MD. Clinically Relevant Electrolytes H 2 O –...

Correction Made Easy By Adrian Paul J. Rabe, MD

Clinically Relevant Electrolytes

• H2O – intracellular

• Na – extracellular

• K – intracellular

• Ca – intracellular

• Mg – intracellular

Water

• ICF: 55-75%

• ECF: 25-45%• Intravascular: Extravascular (1:3)

• Total Body Water• 60% of Body weight (men)

• 50% of Body weight (women, elderly)

• Osmolar Loss vs Free Water Loss• Plasma osmolality = 275-290 mosm/kg

• 2(Na+K) + BUN/2.8 + Glucose/18

• Na is the major determinant of osmolality

• Posm = 2(Na+K) + BUN/2.8 + Glucose/18

• Free water deficit (L) = TBW x ([Actual Na/140]-1)

Water: Exercise

• 55/F with diarrhea

• Poor skin turgor, thirst

• 45 kg

Na 167 Mg 0.55

K 3.1 BUN 2.13

Cl 111 Crea 115

Ca 2.1 Gluc 3.4• Is there water loss?

• Is it osmolar loss or free water loss?• Posm = 346 mOsm/kg

• Free water deficit = 4.34 L

Na: Low

Posm

LowNHigh

Hyperglycemia

Mannitol

Hyperproteinemia

Hyperlipidemia

Bladder irrigation

ECF Volume Primary Polydipsia

Reset osmostat

Urine output

MaximalNon-maximal

Corrected Na (mg/dL) = Na + ((Gluc – 100)/100)

if Gluc > 100

Na: Low

ECF

DecNInc

Heart Failure

Hepatic Cirrhosis

Nephrotic Syndrome

Renal Insufficiency

SIADH

Hypothyroidism

Adrenal Insufficiency

Extra-renal Na loss

Remote diuretic use

Remote vomiting

Na-wasting Nephropathy

Hypoaldosteronism

Diuretics

Vomiting

Urine Na

> 20 mmol/L< 10 mmol/L

Na: Low

• Goals• Restrict water intake

• Promote water loss

• Correct underlying disorder

• ECF volume increased• Isotonic saline: removes stimulus for AVP release

• Water restriction to less than urine output

• Loop diuretics

• ECF volume N• Dietary water restriction

Na: Low

• ECF volume decreased or symptomatic hyponatremia• Correct!

• Na deficit = TBW X (Desired – Actual Na)

• Liters per day = (Na def)/(Infusate Na)• Osmotic Demyelination Syndrome – neurologic disorder with

flaccid paralysis, dysarthria and dysphagia

5% NaCl 855

3% NaCl 513

0.9% NaCl 154

0.45% NaCl 77

0.2% NaCl 34

Plain LR 130

D5W 0

Na: Low

• ECF volume decreased or symptomatic hyponatremia• Correct!


• Liters per day = (Na def)/(Infusate Na)

• But… correct at 10-12 mmol/L per day (e.g. correct from Na 100 to 110-112)

• In a 50 kg female = 12 x TBW = 12 x 25 = 300

5% NaCl 855

3% NaCl 513

0.9% NaCl 154

0.45% NaCl 77

0.2% NaCl 34

Plain LR 130

D5W 0

Hyponatremia: Exercise

• 65/M hypertensive patient

• Deterioration in sensorium

• 60 kg, xerosis, dry armpits

Na 110 Mg 0.46

K 2.9 BUN 2.13

Cl 88 Crea 120

Ca 1.99 Gluc 12.22

• Na corrected = 111.2

• Posm = 242.6 mOsm/kg

• ECF: decreased

• Na def: 900

• Daily Correction: 360

5% NaCl 855

3% NaCl 513

0.9% NaCl 154

0.45% NaCl 77

0.2% NaCl 34

Plain LR 130

D5W 0

Na: High

ECF

Not increasedIncreased

Give hypertonic solutions

(hypertonic NaCl or NaHCO3)Urine Osmolality Water losses

(GI, insensible, remote renal)

Urine output

MinimalNon-minimal

Uosm = 2 (Na + K) + BUN + RBS

Na: High

Uosm

< 750> 750

Diuretics

Osmotic DiuresisCentral DI Nephrogenic DI

DDAVP response

Uosm increase Uosm decrease

Na: High

• Goals• Stop ongoing water loss

• Correct water deficit

• Safest is oral correction

• D5W or pNSS are alternative solutions

• Water deficit = ([Actual Na/140]-1)x TBW

• Change in serum Na/L = (infusate Na-serum Na)(TBW + 1)

• -12/H2O def = (infusate Na-serum Na) (TBW + 1)

• (-12/H2O def)(TBW +1) = infusate Na – serum Na

• Infusate Na = (-12/H2O def)(TBW +1) +serum Na

• -12(TBW +1)/(Infusate Na-serum Na) = Liters

Na: High

• Goals• Stop ongoing water loss

• Correct water deficit

• Safest is oral correction

• D5W or pNSS are alternative solutions

• Water deficit = ([Actual Na/140]-1)x TBW

• Change in serum Na/L = (infusate Na-serum Na) (TBW + 1)

• Na 162 in a 40 y/o 50 kg female

• Deficit: 3.93 L = 4 cycles

• -12/4 = (x-162)/(TBW+1)

• -3(25+1) + 162 = x

• -78+162 = 84

0.9% NaCl 154

0.45% NaCl 77

0.2% NaCl 34

Plain LR 130

D5W 0

Hypernatremia: Exercise

• 21/M with vomiting

• 60 kg, dry buccal mucosa, UO 30cc/3h

Na 180 Mg 1.1

K 3.1 BUN 3.46

Cl 115 Crea 120

Ca 2.4 Gluc 18.9• Na corrected = 182.4

• Posm = 388.6

• Free H20 deficit = 10.9L

• ECF: decreased

• UO: minimal

• Given infusate pLR: 8L/day for 3 days, 4L/day on the 4th day

K: Low

Urine K excretion

< 15 mmol/d> 15 mmol/d

Remote diuretic use

Remote vomiting

Sweat losses

Acidosis

(Urine K/Plasma K)

(Uosm /Posm)

Lower GI K loss

TTKG < 2

Acid-base?

Na wasting nephropathy

Osmotic diuresis

Diuretic

TTKG?

TTKG > 4Acid-base

Vomiting

Bartter’s/Liddle’s

Hypomagnesemia

DKA

RTA

Amphotericin B

AlkalosisAcidosis

Alkalosis

K: Low• Goals

• Correct deficit

• Minimize losses

• K deficit = (Desired – actual)/0.27 – academic only

• K depletion DOES NOT correlate well with plasma K• For every decrement in serum K mmol = 200-400 mmol

deficit

• If ~3.0 to correct to 4.0, give 200-400 mEqs of K

• < 3.0 = >600 mmol

K: Low• Oral correction

• Bananas, fruits

• Oral KCL = 40 mEqs/30 cc

• IV correction (ideally, in saline)• 60 mEqs if via central line

• 40 mEqs if via peripheral line

• Not more than 20 mmol/h unless with paralysis or malignant ventricular arrhythmias

K: High• Goals

• Depends on ECG and weakness

• Measures• Ca gluconate 10% in 10 mL over 2-3 minutes

• NaHCO3 3 vials in saline solution

• Glucose-Insulin solution

• B-adrenergic drugs

• Diuretics

• Dialysis

Ca: High• Goals

• Rule out hyperalbuminemia as a cause

• Corrected Ca = (40-alb) x 0.02 + Ca

• Take intact PTH

• Measures• Forced saline diuresis (e.g. Furosemide 200 mg + pNSS

1L x 6 hours)

• Bisphosphonates (Pamidronate 60-90 mg IV x 2-4 hours)

• Calcitonin

• Phosphate IV

• Glucocorticoids – decrease Vit D production

• Dialysis

Ca: Low• Goals

• Rule out hypoalbuminemia as a cause

• Corrected Ca = (40-alb) x 0.02 + Ca

• Take intact PTH

• Measures• Ca gluconate 10% solution 10 mL + D5 50 cc x 5min

• Ca gluconate drip

• Ca CO3 500 mg BID with meals

• Vit D 2 ug/day

Mg: Low• Goals

• Correct K concentration

• Correct Ca concentration

• Measures• 1g = 0.10 increase in Mg

• MgSO4 3 g in D5W 250 cc x 240 = increase by 0.3

11 Equations to memorize!• Posm = 2(Na+K) + BUN/2.8 + Glucose/18

• Uosm = 2 (Na + K) + BUN/2.8 + Glucose/18

• Corrected Na (mg/dL) = Na + ((Gluc – 100)/100) for Gluc > 100


• Liters per day = (Na def x 1000)/(Infusate Na)

• Water deficit = ([Actual Na/140]-1) x TBW

• Change in serum Na/L = (infusate Na-serum Na) (TBW + 1)

• TTKG = (Urine K/Plasma K)/(Uosm /Posm)

• K deficit = (Desired – actual)/0.27• Corrected Ca = (40-alb) x 0.02 + Ca• Creatinine Clearance = [(140-age) x weight in kg] x 88.4; multiply by 0.85 for females

[72 x Creatinine in umol] • BUN:Creatinine Ratio = (BUN/Crea) in umol x 247

*TBW fraction: 0.6 in males, 0.5 in females and elderly

Before starting any calculation• Correct everything (Na, Calcium)

• Get TBW

• Get BUN:Crea ratio and Creatinine Clearance

• Get Plasma Osmolality

Exercises• 49 y/o female diabetic

• 45 kg

• Vomiting, decreased sensorium

• Dry buccal mucosa, drowsy

• BUN 13.6, Crea 223, Na 168, K 2.2, Cl 110, Mg 0.55, Ca 1.24, alb 23, RBS 21.3

• TBW: 22.5

• Creatinine Clearance: 19

• BUN:Crea Ratio: 15

• Corrected Na: 170.8

• Corrected Calcium: 1.58

• Plasma Osmolality: 380.9 (high)

Exercises• 49 y/o female diabetic

• 45 kg

• Vomiting, decreased sensorium

• Dry buccal mucosa, drowsy


• Hypernatremia

• Free water deficit: 4.95 L

• Change in Na for 1L pLR: -1.74

• Daily: ~7L for 2 days then 3.5 L for the 3rd day

• Hypokalemia: > 600 mEqs correction

• Hypomagnesemia: MgSO4 4g in D5W 250cc x 12-24h

• Hypocalcemia: Ca Gluconate 1 amp SIVP or drip

0.9% NaCl 154

0.45% NaCl 77

0.2% NaCl 34

Plain LR 130

D5W 0

Exercises• 58 y/o male with diarrhea, previously with Lung CA

• 62 kg

• Watery non-bloody diarrhea, poor urine output

• Awake, poor skin turgor, complaining of thirst


• TBW: 37.2

• Creatinine Clearance: 25

• BUN:Crea Ratio: 21

• Corrected Na: 128.6

• Corrected Calcium: 2.99 (mild)

• Plasma Osmolality: 291 (normal to high)

Exercises• 58 y/o male with diarrhea, previously with Lung CA

• 62 kg

• Watery non-bloody diarrhea, poor urine output

• Awake, poor skin turgor, complaining of thirst


• Hyponatremia

• Sodium deficit: 424.08 mEqs

• Daily Sodium correction: 446.4

• pNSS: 2.9L/day

• Hypokalemia: >600 to 1200 mEqs

• Hypomagnesemia: MgSO4 3g in D5W 250cc x 12

• Hypercalcemia: Forced saline diuresis, Pamidronate

5% NaCl 855

3% NaCl 513

0.9% NaCl 154

0.45% NaCl 77

0.2% NaCl 34

Plain LR 130

D5W 0

Correction Made Easy By Adrian Paul J. Rabe, MD. Clinically Relevant Electrolytes H 2 O –...

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Transcript of Correction Made Easy By Adrian Paul J. Rabe, MD. Clinically Relevant Electrolytes H 2 O –...