An 80-year-old woman presented with confusion, weakness, and nonsustained ventricular tachycardia. Her lab results showed hypokalemia (K=2.5 mmol/L), hyponatremia (Na=118 mmol/L), and she was started on IV potassium replacement. Further evaluation of her hyponatremia found she was euvolemic. Her sodium was then found to be elevated at 168 mmol/L and she received hypotonic fluids. Electrolyte imbalances can have serious consequences and require identifying the cause, urgent treatment if life-threatening, and monitoring for correction.

1. Electrolyte Imbalance
12th Nov 2010
‘Primer on Critical Care’

2. ECF vs ICF: Electrolyte composition

3. Case Study
• 80-year-old woman with hypertension and
heart failure
• Confusion, lethargy, poor oral in take and
weakness for 3 days
• BP 108/70 mm Hg, HR 110/min, R18/min
• Nonsustained ventricular tachycardiaon
monitor
What electrolyte disorders might
contribute to her presentation?

4. Case Study
• 80-year-old woman with hypertension and
heart failure
• Confusion, lethargy, poor oral intake and
weakness for 3 days
• Nonsustained ventricular tachycardia on
monitor
• Laboratory value: K 2.5 mmol/L
How would you initiate evaluation
and treatment of this patient?

5. Hypokalemia (K<3.5 mmol/L)
K≤2.5 mmol/L (<3 mmol/L if
on Digoxin)
K<3.5 but >2.5 mmol/L
and No Symptoms
Life-Threatening
Symptoms
Non-Life
Threatening or
No Symptoms
Enteral replacement
KCl 20-40 mmol
every 4-6 h
IV KCl 20-30
mmol/h via
Central Catheter
Enteral replacement
KCl 20-40 mmol every
2-4 h and/or IV KCl 10
mmol/h
Treatment of Hypokalemia

6. Case Study
• 80-year-old woman with hypertension and
heart failure
• ECG
• Laboratory value: K 7.8 mmol/L
How would you initiate treatment of
this patient?

7. Treatment of Hyperkalemia
• Calcium for cardiac toxicity (ECG abnormalities)
• Redistribute potassium
− Insulin and glucose
− Sodium bicarbonate
− Inhaled β2-agonists
• Remove potassium
− Loop diuretic
− Sodium polystyrene sulfonate
− Dialysis

8. Case Study
• 80-year-old woman with hypertension and
heart failure
• Confusion, lethargy, poor oral intake
• and weakness for 3 days
• Laboratory value: Na 118 mmol/L
How would you initiate evaluation of
this patient to determine the etiology?

9. Etiology of Hyponatremia
Hyponatremia
(Na<135 mmol/L)
Presence of
↑ Glucose
↑ Proteins or Lipids
Mannitol
Consider
Hyperosmolar Hyponatremia
Pseudohyponatremia
Hypo-osmolar Hyponatremia
Assess
Volume Status
Urine Osmolarity (Uosm)
Urine Sodium (UNa)
FE Na
Yes
No

10. Etiology of Hyponatremia
Hypovolemia Hypervolemia
Uosm>300 mOsm/L
UNa <20 mmol/L
FE Na <1%
Uosm>300 mOsm/L
UNa >20 mmol/L
FE Na >1%
Uosm>300 mOsm/L
UNa <10-20 mmol/L
FE Na <1%
Vomiting
Diarrhea
Third-Space
Fluid Loss
Diuretics
Aldosterone
Deficiency
Renal Tubular
Dysfunction
Congestive Heart Failure
Cirrhosis
Renal Failure
With/Without Nephrosis

11. Etiology of Hyponatremia
Euvolemia
Uosm <100 mOsm/L
UNa >30 mmol/L
Uosm >100 mOsm/L (usually >300)
UNa >30 mmol/L
Polydipsia
Inappropriate Water
Administration to Children
SIADH
Hypothyroidism
Adrenal Insufficiency

12. Management of Hyponatremia
• Hypovolemic
• Hypervolemic
• Euvolemic
− Restrict free-water intake
− Increase free-water loss
− Replace intravascular volume with normal
saline or hypertonic saline
How fast would you correct the
sodium concentration?

13. •  Na = Na(i) – Na(s)
TBW + 1
= 513 – 108
70(0.6) + 1
= 9.4
(3% NaCl = 513 meq/L)

14. Case Study
• 80-year-old woman with hypertension and
heart failure
• Confusion, lethargy, poor oral intake and
weakness for 3 days
• Laboratory value: Na 168 mmol/L
How would you treat this patient?

15. Treatment of Hypernatremia
• Normal saline if hemodynamically unstable
• Hypotonic fluid when stable
− Intravenous fluids
− Enteral free water
• Quantity
H2O deficit (L) = [0.6 × wt (kg) ] × [Measured Na -140]
140
• Rate of correction

16. Magnesium : reference range
Fluid
mEq/L mg/dl SI units
(mmol/L)
Serum
Total 1.4-2.0 1.7-2.43 0.7-1.0
Ionized 0.8-1.1 0.97-1.46 0.4-0.6
Urine 5-15
mEq/24 hr
6.1-18.25
mg/24hr
2.5-7.5
mmol/24 hr

17. SI Conversion factor for Mg
• 1 mg/dL = 0.411 mmol/L
• 1g MgSO4 = 4mmol of Mg = 8mEq of Mg

18. Replacement protocol
Life threatening hypomagnesemia (associated with
serious cardiac arrhythmias or generalized seizures)
1 2g MgSO4 IV over 2-5 min.
2 5g MgSO4 infusion over next 6 hrs
3 Continue 5g MgSO4 every 12 hrly for next 5 days.
Hypomagnesemia & Renal insufficiency
Chronic diarrhea & Cr. Clearance > 30 mL/min.
< 50% of Mg should be administered
Monitor S. Mg closely

19. Calcium
Traditional units
(mg/dL)
Conversion factor SI units
(mmol/L)
Total Ca 9.0-10.0 0.25 2.2-2.5
Ionized Ca 4.5-5.0 0.25 1.1-1.3

20. Calcium replacement therapy
Solution Elemental Ca Unit
vol.
Osmolarity
(mOsm/L)
10% CaCl2 27mg(1.36mEq)/mL 10mL 2000
10% Ca
gluconate
9mg(0.46mEq)/mL 10mL 680mOsm/L
Infuse in large veins
Give bolus dose 200mg over 10min.
Cont. infusion 1-2 mg elemental Ca/kg/hr for 6-12 hrs

21. Phosphorus : levels
mmol/L mg/L
Normal 0.8-1.5 25-47
Hypophosphatemia
Low 0.5-0.7 15-24
Severe <0.5 <15
Hyperphosphatemia
Mild to mod. 1.5-2.6 47-80
Severe >3.2 >100

22. Hypophosphatemia : replacement
therapy
Preparation mg mmol
Ostocalcium (1 tab) 62 2
Proctoclysis enema (1ml) 27 0.8
Omilcal syrup (1ml) 6.2 0.2
2 Tab = 5 ml Proctoclysis = 20 ml Syrup

23. Principles of Electrolyte
Disturbances
• Treat the electrolyte change, but search
for the cause
• Clinical manifestations are usually not
specific to a particular electrolyte change
• Clinical circumstances determine urgency
of treatment rather than electrolyte
concentration
• Frequent reassessment of electrolyte
abnormalities required