1. General Internal Medicine
Electric-Lytes
Dr. Jeffrey P Schaefer
General Internal Medicine 1

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3. Objectives Case based approach to abnormal Sodium Potassium Calcium
Magnesium
Phosphate

4. Sodium

6. Warm Up Case 81 yr old female presents to ER recent viral illness
vomiting and diarrhea
Na  125 mmol/l

7. What are the clinical features of hyponatremia?

8. Hyponatremia Neuromuscular Irritability
mild anorexia
headache
muscle cramps
irritability
delirium
coma
seizure
Rate of Reduction affects clinical severity

9. What are the causes of hyponatremia?

11. Common Causes Volume Depletion Edema Water excess Salt loss
diuretics (esp thiazide), vomiting, diarrhea
Edema
heart failure, nephrosis, cirrhosis
Water excess
SIADH, polydipsia, iatrogenesis
Salt loss
hypoadrenal, hypoT4, cerebral salt wasting
Shift (pseudohyponatremia)
hyperglycemia, hyperlipidemia

13. Case 81 yr old female presents to ER malaise recent viral illness
vomiting and diarrhea
Na = 125 mmol/l

14. How should this case be managed?

15. Orders
Solution?
Volume?
Rate(s)?
Reassess?

16. Orders Solution? Volume? Rate(s)? Reassess? Normal Saline
1 – 4 l according to clinical assessment
250 – 500 / hr x 1 l, then 100 – 150 ml/hr
clinical reassess in 4 – 6 hours
recheck lab in 24 hours

17. Sodium, Salt What’s in Normal Saline? NaCl 154 mmol/l
Na 154 mmol + Cl 154 / litre

18. Sodium, Salt What’s in Normal Saline? Implication for heart failure
NaCl 0.9% w/v
0.9 grams solute per 100 grams solvent
0.9 grams salt per 100 grams water
9 grams salt per 1,000 grams water
9 grams salt per 1,000 ml water
Normal Saline is NaCl 9 g / l
Implication for heart failure
Mw(NaCl) = = g/mol
Na accounts for (23/35) ~ 40% weight of salt
Low Salt Diet = 2 g of sodium = 1 tsp
Low Salt Diet = 2 g / 0.4 = 5 g NaCl
Low Salt Diet = 555 ml of normal saline

19. What Other Flavors of IV Do We Have?

20. Sodium, Salt, Sugar Na+ mmol/l Dextrose in Water 0 ½ Normal Saline 77
Ringer’s Lactate* 130
Normal Saline 154
Hypertonic Saline 513
* Ringer’s Lactate:
Na+ 130 mmol, K+4 mmol, Ca mmol, Cl− 109 mmol, lactate 28 mmol
electrolyte content is isotonic (273 mOsmol/liter) in relation to the extracellular fluid (approx. 280 mOsmol/liter).

21. Case 82 year old female in ER HTN on thiazide
presents with seizure and coma
estimated weight 60 kg
Na = 105 mMol

22. How should this case be managed?

23. Sodium Deficit Calculated sodium deficit
*0.6 males x (weight in kg) x (desired sodium - actual sodium) *0.5 for females
desired range is 105 mmol/l + 5 mmol/l = 110 mmol/l
hypertonic saline has 513 mMol / l of Na

24. Sodium Deficit
*0.5 x (weight in kg) x (desired sodium - actual sodium) *0.5 for females for males
desired increase = 105 mmol/l + 5 mmol/l = 110 mmol/l
0.5 x 60 kg = 30 l
30 l x 5 mmol/l = 150 mmol
hypertonic saline has 513 mMol / l of Na
150 / 514 = 300 ml
300 ml over 1 or 2 hours then reassess OR
100 ml bolus x 10 min, then another, then another...
REASSESS CLINICALLY and BIOCHEMICALLY q 1-2h

27. Rapid Correction of Hyponatremia
central pontine myelinolysis risk
risk is minimal if increase is 0.5 – 1.0 mmol/h

28. Case 30 year old female presents to ER was hiking in the mountains
drank 10 liters of water per day on the advice of a well meaning friend
delirium with paranoia
Na = 110 mmol/l ?

30. Case 78 year old female on general surgery
Post-op day 3 hemicolectomy for Duke B ca
Overnight developed delirium
Post-op IV order: ‘2/3 – 125 ml/h’
Na = 120 mMol

31. Case 19 year old man presents to ER progressive weakness
anorexia and weight loss
nauseated
unusually tanned!
Na = 128 mMol, K = 6.5 mMol

33. Case 82 year old female in clinic HTN on thiazide feels well
Na = 125 mMol

34. Case 65 year old man on neurosurgery post-op day 2 brain aneursym clip
Na = 129 mMol

35. Case 59 year old female presents with pneumonia day 4 feels strange
can eat and drink, likes tea
Na = 120 mMol

36. SIADH water restriction is mainstay diuretics maybe
vaptans... probably not yet

37. Vaptans ADH antagonist - Tolvaptan (Samsca, Otsuka) in Canada
- 15 – 30 mg tablets..... $120 / day
- black box warning re: hepatic toxicity

39. Warm Up Case 81 year old female on stroke unit
doing poorly over last few days
now unconscious
Na = 176 mMol (normal mMol)

40. What are clinical features of hypernatremia?

41. Clinical Features Hypernatremia lethargy weakness irritability
twitching
delirium
reduced level of consciousness
coma
seizures
‘neuromuscular irritability’

42. What are the causes of hypernatremia?

44. DDx – HyperNa+ Not enough water! no thirst can’t act on thirst
can’t retain water
except for Normal Saline, not usually a salt issue

45. Case 81 year old female on stroke unit doing poorly over last few days
now unconscious
Na = 176 mMol (normal mMol)
estimated weight 60 kg

46. Diagnosis?
Management?
Solution
Volume
Rate

47. Solution Na+ mmol/l Dextrose in Water 0 ½ Normal Saline 77
Ringer’s Lactate* 130
Normal Saline 154
Hypertonic Saline 513
* Ringer’s Lactate:
Na+ 130 mmol, K+4 mmol, Ca mmol, Cl− 109 mmol, lactate 28 mmol
electrolyte content is isotonic (273 mOsmol/liter) in relation to the extracellular fluid (approx. 280 mOsmol/liter).

48. Correct no faster than 0.5 – 1 mmol / hr
Rate of Correction
Correct no faster than 0.5 – 1 mmol / hr
Risk of cerebral edema
determine water deficit
determine duration of correction
rate = deficit / duration (index to hour)
consider ongoing losses
decide on re-assessment

49. Volume Water Deficit (Na+ measured – 140 mmol/l)
0.6 x kg
140 mmol/l
use 0.5 for females
desired = 140 mMol

50. Calculate Free Water Deficit
(176 mmol / l – 140 mmol/l)
0.5 x 60 x
140 mmol/l
7,710 ml
36 mmol / 0.5 – 1.0 mmol/hr = 48 hr
160 ml/hr of ‘free water’
D5W or tube water at 160 ml/hr

51. Advanced Case 55 year old female pituitary resection
post-op dilute polyuria
Na = 165 mMol

52. DDAVP
IV / sq  1-2 ug q12 h
nasal  10 – 40 ug / day (divide bid / tid)
oral  0.1 – 1.2 mg / day (divide bid / tid)
give hypotonic IV while getting control
usually this is a planned event

55. Warm Up Case 78 year old presents with sob recent gout indomethacin
creatinine 790
K = 7.0 mMol

56. What are the clinical features of hyperkalemia?

57. Clinical Features
death

60. What are the causes of hyperkalemia?

62. Potassium Hyperkalemia: Pseudohyperkalemia acute renal failure
pre-renal
renal: especially *drugs and toxins (acute!)
post-renal
too much K
ACE-I, ARBs, spironolactone, NSAIDs
Pseudohyperkalemia
check CBC and phlebotomy

63. Case 78 year old presents with sob recent gout indomethacin
creatinine 790
K = 7.0 mMol

64. Case Restore renal function Remove K from body Shift K into cells
D5-normal-bicarb (3 amps bicarb into 850 ml of D5W
kaliuresis  loop diuretic
remove obstruction
Remove K from body
K binder  Resonium or Kayexalate
New Kids on the block... sodium zirconium cyclosilcate (ZS-9)and patiromer (Veltassa)
laxative
Shift K into cells
create alkalosis, insulin, glucose, salbutamol
Plan for Dialysis (order HBsAg, nephro)

65. Case General Principles optimize cardiac output
mitigate all nephrotoxicity
minimize potassium sources

66. Case 78 year old man with CLL routine blood work WBC = 75,000 x 109/l
ECG normal

68. Case 65 year old man post-op day 4 cholecystectomy NS at 125 ml/hr
K = 2.8

69. What are the clinical features of hypokalemia?

70. Clinical Features hypokalemia muscle twitch / spasm dysrythmia
increase risk of atrial fibrillation

71. What are the causes of hypokalemia?

73. Hypokalemia Epidemiological Approach diuretics failure to supplement
vomiting (suction) & diarrhea
hypomagnesemia
amphotericin, platinum based chemotx

74. Normal and Flat ST

79. How can potassium be replaced?

80. Potassium Replacement
Oral whenever possible
KCl tablet 8 mEq (slow-K, micro-K)
KCl tablet 20 mEq (K-Dur)
KCl tablet 25 mEq (K-lyte effervescent)
KCl solution 10%
IV if needed
20 – 40 mMol / l added to IV
10 mMol / hour max

81. Can hypokalemia be prevented among patients who need diuretics?

82. Potassium Avoid Kaliuresis
you can add / use potassium sparing diuretics

83. Case 24 year old female presents to ER nausea, vomiting Na = 132
K = 6.8
Cl = 100
HCO3 = 5
glucose = 28

84. Case
Diabetic Ketoacidosis
potassium shift

85. Summary Diagnosis and Treatment: hyponatremia hypernatremia
hyperkalemia
hypokalemia

88. Case 58 year old female post-op hour 6 neck surgery
twitchy and trouble breathing
Calcium = 1.7 mMol (2.15 – 2.30 mMol)

90. DDx - hypocalcemia In hospital injured parathyroid glands
acute pancreatitis
uncorrected calcium for albumin

91. measured Ca + [(40 – alb) x 0.02]
Albumin Correction
Corrected Ca =
measured Ca + [(40 – alb) x 0.02]
e.g.
albumin is 20 g/l
measured Ca = 1.90 mmol
correction is  20 x 0.02 = 0.4
= 2.30 mMol

92. Case 58 year old female post-op hour 6 neck surgery
twitchy and trouble breathing
Calcium = 1.7 mMol (2.15 – 2.30 mMol)

93. Calcium Replacement Oral Preferred IV if emergency
Calcium carbonate (500 mg elemental)
dose according to situation
vit D3  0.25 to 0.5 ug od
IV if emergency
10% ca-gluconate 90 mg / 10 ml x 1 to 2 ampules each over 3 – 5 minutes or longer
10% ca-chloride 270 mg / 10 ml (AVOID)

94. IV Calcium for EMERGENCY
10% Ca-gluconate x 6 amps into 500 ml of D5W = 540 mg / 560 ml = ~ 1 mg/ml
0.25 – 0.50 mg / kg / hour infusion
BE CAREFUL – GOOD IV NEEDED
MONITOR FREQUENTLY
CO-ADMINISTER ORAL AND VIT D so as to GET OFF IV ASAP

96. Case
59 year old female with breast cancer
obtunded
Ca = 4.5 mMol

97. Calcium Hypercalcemia constipation abdominal pain general achiness
depressed mood
decreased LOC
coma

99. DDx Hypercalcemia Malignancy Hyperparathyroidism
Excess Calcium / Vit D
Fracture
Bed rest

100. Case
59 year old female with breast cancer
obtunded
Ca = 4.5 mMol

101. Calcium Case Calciuresis Bisphosphonate Saline load Furosemide
Zoledronic acid (Zometa)
Pamidronate, Clodronate

103. Case 34 year old homeless man presents Feels poorly
Day 2 PO4 = 0.20 mMol (0.8 – 1.5 mMol)

104. Ddx – Hypo PO4

106. Hypophophatemia Refeeding (> 95%) Hyperparathyroidism
diabetic keto-acidosis
anorexia
enteral or parenteral nutrition
Hyperparathyroidism

107. Case 34 year old homeless man presents Feels poorly
Day 2 PO4 = 0.20 mMol (0.8 – 1.5 mMol)

108. Phosphate
Sandoz Phosphate
Milk and Food

111. Case 55 yr old alcoholic blood tests done
Mg = 0.8 mMol (1.2 – 2.2 mMol)

112. Hypomagnesemia Magnesium sulfate 1 to 5 grams IV Per Protocol!
hypotension
chest tightness
flushing
Oral is ‘okay’ but can cause diarrhea