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?
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?
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
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
