This document discusses fluid and electrolytes in the human body. It provides information on: - Water content and distribution in the body - Distribution of electrolytes like sodium, potassium, calcium, and magnesium between intracellular, interstitial, and intravascular fluid compartments - Daily water requirements - Causes, signs, and treatments of electrolyte abnormalities like hyponatremia, hypernatremia, hypokalemia, hyperkalemia, hypocalcemia, and hypercalcemia.

1. Fluid and Electrolytes

2. Water Content
• 50 to 60% of body weight
• Higher in neonates and children
• Lower in elderly
• Lower in women

3. 52
21
14
13
39
27
18
16
18
36
24
22
0%
20%
40%
60%
80%
100% Solids
ECW
ICW
Fat

5. Intracellular
Interstitial
Intravascular
2/3 1/3
3/4 1/4

6. Intracellular
Interstitial
Intravascular
2/3 1/3
3/4 1/4
ECF osmolality = ICF osmolality
K, ATP
Creatinine PO4
phospholipids
Na, Cl
HCO3

7. Intravascular
Interstitial
3/4 1/4
Capillary membrane
Plasma proteins

8. Intracellular
Interstitial
Intravascular
2/3 1/3
3/4 1/4
Na
K
Plasma
Na 153
IC K 150

9. Water Loss - Starvation
Intracellular Interstitial
Intravascular
2/3 1/3
3/4 1/4

10. Water & Electrolyte Loss -- GI
Intracellular
Interstitial Intravascular
2/3 1/3
3/4 1/4

11. Replacement Fluids 5% Dextrose
Intracellular
Interstitial
Intravascular
2/3 1/3
666ml 250ml 84ml

12. 1L of Crystalloid
Intracellular
Interstitial
Intravascular
2/3 1/3
750ml 250ml

13. 1L of Colloid
Intracellular
Interstitial
Intravascular2/3 1/3
1000ml

14. 1L of Colloid
Intracellular
Interstitial
Intravascular2/3 1/3
1000ml

15. Sepsis / Shock
Intracellular
Interstitial
Intravascular
2/3 1/3
3/4 1/4
Na

16. Daily Water Requirement
Weight Water requirement
0-10 kg 4mL/kg/hr
10-20 kg 40mL/hr +2ml/kg/hr for each kg>10kg
>20kg 60ml/hr +1ml/kg/hr for each kg>20kg
for 60kg man this = 100ml/hr or 2400 ml/24 hrs
for normal people!!

17. Ca 2+
Mg 2+
K+
Na+
Cl-
PO4
3-
Organic
anion
HCO3
-
Protein
0
50
50
100
150
100
150
Cations Anions
ECFICF

18. Solutions Volumes Na+
K+
Ca2+
Mg2+
Cl- HCO3
-
Dextrose mOsm/L
ECF 142 4 5 103 27 280-310
Lactated
Ringer’s
130 4 3 109 28 273
0.9% NaCl 154 154 308
0.45% NaCl 77 77 154
D5W 50 250
D5/0.45%
NaCl
77 77 50 406
3% NaCl 513 513 1026
6%
Hetastarch
500 154 154 310
5% Albumin 250,500
130-
160
<2.5
130-
160
330
25% Albumin 20,50,100
130-
160
<2.5
130-
160
330

19. Hyponatremia
• Serum sodium concentration to a level
below 136 mmol per liter
• hyponatremia can be associated with low,
normal, or high tonicity

20. Hyponatremia
• Clinically associated with mainly CNS
changes
• Headache, nausea, vomiting, muscle
cramps,lethargy, restlessness,
disorientation, and depressed reflexes

21. Hyponatremia
• 32-year-old woman has three grand mal
seizurestwo days after an appendectomy
• 3L of 5 % D5W infused during 1st
PO day
• Unknown oral fluids
• O/E she is euvolemic, and weighs46 kg

22. • S Na is 112 mmol per liter
• S K is 4.1 mmol per liter
• S osmolalityis 228 mOsm / Kg of water
• Urine osmolality is 510mOsm / Kg of water

23. 513 –112
23 + 1
1L of 3% Nacl will inc Na by 16.7 meq
60ml will increase Na by 1 meq

24. • EBWater 23 litres
Na now 112 x 23
If you give 1L of 3% saline
(513 x 1) + (112x 23)
New conc of Na = (513 x 1) + (112x 23)/24
diff of Na = [(513 x 1) + (112x 23)/24] – (112)

25. Rate of correction:
Can we exceed 1.5 mEq/L/hr?
Total Correction:
Should we limit it to less than 12mEq/L for the first 24 hrs?
What is the level to which we should correct the sodium?
Full correction?
Limit to 120-125 mEq/L?
Should we treat all hyponatremia? What if the patient is
asymptomatic ?

26. Outcome in severe symptomatic hyponatremia:
Age (extremes do well; infants and elderly)
Sex (women fare poorly)
Respiratory arrest always worsens outcome
Rate of correction is not a major factor as long as
the total correction in 24 hours is limited
Common causes:
Euvolemic: SIADH, Psychogenic polydipsia, hypothyroid
Overloaded: Renal, liver, heart failure
Dry: Diuretic abuse, GI losses, adrenal hypofunction

27. Effects of Hyponatremia on the Brain
Quadriplegia
Pseudobulbar palsy
Seizures
Coma
Death
Hepatic failure
K depletion
malnutrition

28. Hypernatremia
Na >145
Usually due to dehydration:
Water loss: GI losses, sweating, Diabetes Insipidus
Inadequate intake: Access to water impaired
Excessive salt intake is an unusual cause
Correct with NS if patient is hypotensive
Use hypotonic solutions otherwise

29. Hypernatremia

30. Hypernatremia

31. My Surgery Is Postponed!
You had admitted a 67 year old diabetic with end-stage
renal disease, who has been undergoing thrice-weekly
dialysis, for the placement of a new A-V fistula. The case
has to be postponed by a day because of another emergency.
The next morning, as you arrive to see your patient a
panicky nurse informs you that he is hypotensive (BP 80/sys.)
and has a heart rate of 38/min. A “sharp”medical intern
had administered atropine without successfully improving
the blood pressure or heart rate.
What
investigation / laboratory test
monitoring device
would you request emergently?

32. Treatment of this patient should be based on all of the
following EXCEPT:
a. There should be no delay in treatment, waiting for
the electrolyte imbalance to be confirmed by the lab
b. Administration of intravenous calcium (chloride or
gluconate) is the first step
c. Sodium bicarbonate is needed
d. Parenteral administration of an ion exchange resin
(kayexelate) is needed
e. Glucose / insulin will help

33. Hyperkalemia:
Common Causes:
Renal Failure, Acidosis
Drugs: K-sparing diuretics, ACE inhibitors
Cell death: burns, rhabdomyolysis
Pseudohyperkalemia is an in-vitro rise in K associated with
WBC > 100K/mm3
or platelets > 600K/mm3
Haemolysis should also be considered
ECG changes:Peaked T, wide PR&QRS, bradycardia, heart
block

34. Hyperkalemia:

35. Post Op Ileus
A 47 year old with a history of bronchial asthma has
undergone an open cholecystectomy. His postoperative
recovery has been complicated by respiratory distress
due to exacerbation of asthma. He is already on peri-op
ampicillin, gentamicin and metronidazole. Since his
asthma did not respond to 2-hourly nebulized salbutamol
he has been given parenteral steroids. With poor
mobilization of secretions he has developed atelectasis of
the R lung base and moderate hypoxia. A physician had
advised the administration of lasix to help improve PO2
Even though it is now the third post-op day, the patient has
an ileus with RT returns of nearly 1200 ml / day.

36. Electrolyte Concentration in Body Fluids
Na K Cl HCO3
Saliva Low Moderate Low Moderate
Bile High Low Moderate Moderate
Stomach Moderate Variable Low None
Small gut High Low Low High
Diarrhea Low High Low Moderate
Sweat Moderate Low Moderate None

37. Na and K
• Daily requirements
– Na 1 to 2 mEq / Kg / day
– K 1 mEq / Kg / day

38. Seizures Followed by Unresponsiveness
A52-year-old woman had undergone a mastectomy and
axillary node dissection about 11 years ago. She was node
positive and received combination chemotherapy. She
had otherwise been well till 2-3 days prior to admission, when
has been complaining of nausea, vomiting and anorexia. She
was noted to be irritable and then increasingly somnolent.
She was brought to your hospital after she had a single
generalized convulsion after which she has not awoken. The
family also notes that she has been voiding large quantities
of urine and has been bedwetting in the last two days.
A contrast CT scan of the brain shows no abnormality.

39. Which of the following would be logical explanations
for the patient’s symptoms (arrange in decreasing order
of likelihood):
A. Despite a negative CT scan, brain mets. and associated
diabetes insipidus should be considered. Hypernatremia
may be the cause of symptoms.
B. Mets. to other sites producing ectopic ADH may be
causing hyponatremia and an associated encephalopathy
C. Since metastaic breast cancer is a common cause
of hypercalcemia, we must consider this as the most likely
etiology.
What laboratory investigations would you ask for?

40. “Routine” laboratory values are
received:
Na = 152 mEq/L
BUN = 50 mg/dl
Cr. = 2.0 mg/dl
BP = 90/50 mm Hg
HR = 130 frequent PVC's

41. Ca = 16 mg/dl
Immediate management should include:
a. Disodium etidronate (biphosphonate) to lower Ca levels
b. Immediate hydration with NS; followed by 1/2NS to
provide 4-6litres/day + lasix or ethacrynic acid
c. Immediate hydration with 5%dextrose followed by fluid
to correct 1/2 the estimated free water deficit based on S. Na
d. Immediate dialysis with Ca free dialysate
e. Calcitonin + steroids

42. Hypercalcemia
Causes:
Malignancy Lung 35%
Breast 25%
Hematological 14%
Head & Neck 6%
Renal 3%
Hyperparathyroid Solitary adenoma 80%
Hyperplasia 15%
Malignancy <5%
Sarcoid and granulomatous disease
Vitamin A&D intoxication
90%
of
all

43. Hypercalcemia
Signs & symptoms:
Mental:
Stupor, obtundation, apathy, lethargy, confusion, coma
Neurological:
Reduced muscle tone, reflexes
GI& Renal:
Nausea, vomiting, constipation, polyuria, polydypsia
ECG:
Short QT, arrhythmia

45. Case 4:
In this case which of the following maneuvers will help
resolution of the ileus:
a. D/C ampicillin
b. D/C gentamicin
c. D/C flagyl
d. Avoid inhaled salbutamol
e. Switch to parenteral salbutamol
f. Change parenteral to inhaled steroids
g. Administer iv calcium gluconate
h. Administer iv magnesium sulphate
i. D/C lasix
j. D/C Ryle’s tube
h. Improve the asthma
W
hatisthedefinitivetreatm
ent?

46. Hypokalemia

47. Case 5:
A 78 year old male with no known medical illness had
presented with septic shock due to a large bowel perforation,
which has been treated with a colostomy and antibiotic Rx.
He has needed ventilatory and haemodynamic support
but has stabilized. His weaning off the ventilator is compromised
by inadequate patient effort. He is receiving enteral feeding and is
tolerating about 100cc/hr (1800 Kcal/day). The only abnormal
laboratory values are:
S. Calcium (total) 6.2mg/dl,
S. Albumin 2.0 g/dl,

48. Case 5:
In this case, it would be absolutely imperative to:
a. Administer albumin to improve nutritional parameters
and enhance weaning from the ventilator
b. Administer 10 ml (1 amp) of calcium gluconate (~90 mg)
at once and follow-up with an infusion of 0.3-2 mg/kg/hr
c. Use calcium “chloride” instead of “gluconate” because
its actions are more rapid in onset.
d. Provide no treatment, though there is severe hypocalcemia,
as the patient is otherwise asymptomatic
e. Provide no specific treatment, as the clinical and lab
parameters are not of concern in the short run

49. Case 6:
A45 year-old has undergone repeat surgery for the Rx
of hyperparathyroidism. His prior surgery over a year ago
did not provide symptomatic or biochemical improvement.
There is no available documentation of the procedure
performed and amount of parathyroid tissue removed. By the
evening of the surgery the patient develops hyperreflexia,
carpopedal spasm and paresthesias. After initial treatment
with injectable calcium preparations he is placed on oral
doses of nearly 2.5 g of elemental calcium / day. About 10
days from the surgery he has persistent hyperreflexia
and has an ionized Ca of 1.0 mmol/L and PO4 is 5.9 mg/dl

50. Case 6:
Further treatment should include:
a. Lower the phosphate levels by antacids or sucralfate
b. Evaluation for and correction of magnesium deficits
c. Increase the oral calcium supplements
d. Addition of vitamin D supplements

51. Causes of Hypocalcemia
Chronic renal failure
Hypoparathyroidism
Acute Pancreatitis
Sepsis
Burns, rhabdomyolysis
Hypomagnesemia
Massive transfusion