Electrolyte Disorders

Electrolyte Disorders
ByBy
Prof. Moustafa RizkProf. Moustafa Rizk
Prof. of Clinical PathologyProf. of Clinical Pathology
Faculty of Medicine, University of AlexandriFaculty of Medicine, University of Alexandria.a.
10/12/17 06:00 1

Total Body Water
 Total body water (60% total body weight)
 Intracellular volume (40% total body weight)
 Extracellular volume (20% total body weight)
10/12/17 06:00 2

Fluid Compartments
 Fluid Compartments are divided by water-
permeable membranes.
 Intracellular space is separated from the
extracellular space by the cell membrane.
 The capillary membrane separates the
components of the extracellular space.
Intravascular space – capillary membrane – interstitial space
10/12/17 06:00 3

Total Body Water
10/12/17 06:00 4

Total Body Water
 TBW is 55% of a man’s weight
 TBW is 45% of a woman’s weight
 TBW is 80% of an infant’s weight
 Obese individuals have less TBW per
weight than non-obese individuals
10/12/17 06:00 5

Composition of Body Fluids
10/12/17 06:00 6

Composition of Body Fluids
1. Electrolytes have greater osmotic power because
they dissociate in water.
2. The major cation in extracellular fluids is sodium,
and the major anion is chloride; in intracellular fluid
the major cation is potassium, and the major anion
is phosphate.
3. Electrolytes are the most abundant solutes in body
fluids.
10/12/17 06:00
7

Intracellular Fluid Compartment
 High concentration of
 Potassium
 Phosphate
 Magnesium
 Sodium-potassium pump maintains the high
concentration of K+ in ICF.
10/12/17 06:00 8

Sodium-Potassium Pump
10/12/17 06:00 9

Extracellular Fluid Compartment
 High concentration of
 Sodium
 Chloride
 Intravascular Fluid (plasma)
 High concentration of osmotically active plasma
proteins.
Albumin
 Capillary membrane essentially impermeable to plasma
proteins and they stay in the vascular space.
 Interstitial Fluid
10/12/17 06:00 10

Fluid Movement Among
Compartments
1. Anything that changes solute concentration in any compartment
leads to net water flows.
2. Nearly protein-free plasma is forced out of the blood by hydrostatic
pressure, and almost completely reabsorbed due to colloid osmotic
(oncotic) pressure of plasma proteins.
3. Movement of water between the interstitial fluid and intracellular fluid
involves substantial two-way osmotic flow that is equal in both
directions.
4. Ion fluxes between the interstitial and intracellular compartments are
restricted; but movement of nutrients, respiratory gases, and wastes
typically occur in one direction.
10/12/17 06:00 13

Fluid Movement Among
Compartments
10/12/17 06:00 14

Water Balance and ECF
Osmolality
For the body to remain properly hydrated, water
intake must equal water output.
1. Most water enters the body through ingested
liquids and food, but is also produced by cellular
metabolism.
2. Water output is due to evaporative loss from lungs
and skin (insensible water loss), sweating,
defecation, and urination.
10/12/17 06:00 15

Water Balance and ECF
Osmolality
10/12/17 06:00 16

Fluid Volume Disorders
 Osmolarity
• The number of osmoles of a solute in a liter of solution
 Osmolality
• The number of osmoles of a solute in a kilogram of
solution
 Tonicity
• How a solution affects cell volume
• For example – isotonic, hypertonic, hypotonic
10/12/17 06:00 17

Hyponatremia
1. Defined as serum [Na+] less than 136
mEq/L
2. Water shifts into cells causing cerebral
edema
3. 125 mEq/L – nausea and malaise
4. 120 mEq/L – headache, lethargy,
obtundation
5. 115 mEq/L – seizure and coma
10/12/17 06:00 19

Hyponatremia
1. Assess plasma osmolality
2. Assess volume status of patient
Hypervolemic, Euvolemic, Hypovolemic
3. Assess Urine Sodium Concentration
Needed for definitive diagnosis, not needed for treatment
purposes
4. Calculate Na+ Deficit
0.6 x weight (kg) x (130 – plasma [Na+])
5. Correct at no more than 0.5mEq/L per hour or 12
mEq/L per 24 hours
10/12/17 06:00 20

Iso-osmotic and Hyperosmotic
Hyponatremia
Iso and Hyperosmotic hyponatremia are due to excessive solutes in
plasma.
1. Iso-osmotic ( Sosm = 280-300 meq/L)
A. Pseudohyponatremia – No treatment necessary
I. Hyperlipidemia ( Triglycerides > 1500)
II. Hyperproteinemia ( Elevated serum protein >10)
B. Isotonic Infusions
I. Glycine
II. Mannitol
2. Hyperosmotic (Sosm >300 )Treat underlying cause
A. Hyperglycemia
I. Each 100 mg/dl of glucose reduces [Na+] by 1.6 mEq/l
B. Hypertonic Infusions
I. Glycerol
II. Mannitol
III. Glycine
10/12/17 06:00 21

Causes of Hyponatremia can be
classified based on either volume
status or ADH level
1. Hypovolemic, Euvolemic or
Hypervolemic
2. ADH inappropriately elevated or
appropriately suppressed
10/12/17 06:00 22

Hyposmotic Hyponatremia
Assess volume status ( Sosm< 280)
1. Hypervolemic – cirrhosis, heart failure,
nephrotic syndrome
2. Euvolemic – polydipsia, SIADH
(Syndrome of inappropriate antidiuretic
hormone hypersecretion)
3. Hypovolemic – most common cause
Excessive renal (diuretic) or GI (emesis,
diarrhea) losses
10/12/17 06:00 23

ADH suppresion
Conditions which ADH is suppressed
1. Primary Polydipsia
2. Low dietary solute intake “Tea and Toast
syndrome”
3. Advanced Renal Failure
10/12/17 06:00 24

ADH elevation
Conditions which ADH is elevated
1. Volume Depletion
1. True volume depletion (i.e. bleeding)
2. Effective circulating volume depletion (i.e. heart
failure and cirrhosis)
2. Exercised induced hyponatremia
3. Thiazide Diuretics
4. Adrenal insufficiency
5. SIADH (Syndrome of inappropriate antidiuretic
hormone hypersecretion)10/12/17 06:00 25

First step in Assessment: Are
symptoms present?
1. Hyponatremia can be asymptomatic and found
by routine lab testing
2. It may present with mild symptoms such as
nausea and malaise (earliest) or headache and
lethargy
3. Or it may present with more severe symptoms
such as seizures, coma or respiratory arrest
10/12/17 06:00 26

With no severe symptoms and fluid restriction
started, next step is to assess volume
status to help determine cause
1. Hypovolemic – urine output, dry mucous
membranes, sunken eyes
2. Euvolemic – normal appearing
3. Hypervolemic – Edema, past medical
history, Jaundice (cirrhosis), S3 (CHF)
10/12/17 06:00 27

Workup for Hyponatremia
1. 3 mandatory lab tests
A. Serum Osmolality
B. Urine Osmolality
C. Urine Sodium Concentration
2. Additional labs depending on clinical
suspicion
A. TSH, cortisol (Hypothryoidism or Adrenal
insufficiency)
B. Albumin, triglycerides and SPEP
(psuedohyponatremia, cirrhosis, MM)
10/12/17 06:00
28

How to interpret the tests?
1. Serum Osmolality
 Can differentiate between true hyponatremia,
pseudohyponatremia and hypertonic
hyponatremia
1. Urine Osmolality
 Can differentiate between primary polydipsia
and impaired free water excretion
1. Urine Sodium concentration
 Can differentiate between hypovolemia
hyponatremia and SIADH
10/12/17 06:00
29

Correction of Sodium Deficit
Example: A 60 kg woman with a plasma sodium
concentration of 120mEq/L:
Sodium deficit = TBW x (130 – [Na+]p)
Sodium deficit = 0.5 x 60 x (130-120) = 300mEq
3% NaCl contains 513 mEq sodium/L
Volume of 3% NaCl needed = 300/513 = 585 mL
At 0.5 mEq/L/hr a correction of 10 mEq should be done over
20 hours
So, 585 mL/20 hours = 29 mL/hour of 3% NaCl
10/12/17 06:00 31

Hypernatremia
1. Defined as serum [Na+] greater than
146 mEq/L
2. Lethargy, weakness, and irritability
that progress to seizure, coma, and
death
3. Usually occurs in adults with altered
mental status or no access to water
10/12/17 06:00 32

Hypernatremia
1. Assess volume status
2. Measure urine [Na+]
3. Calculate water deficit
0.6 x weight (kg) x ([Na+]/140 -1)
4. Correct with free water no faster
than 0.5 mEq/L/hour or 12
mEq/L/day10/12/17 06:00 33

Hypernatremia
1. Hypovolemic – loss of hypotonic fluids
 Diuresis, vomiting, diarrhea
1. Isovolemic – loss of free water
 Diabetes insipidus, hypodipsia
1. Hypervolemic – gain of hypertonic
fluids
 Hypertonic saline administration
10/12/17 06:00 34

Hypokalemia
1. Defined as serum [K+] less than 3.6
mEq/L
2. Occurs in up to 20% of hospitalized
patients
3. 2.5 mEq/L – muscular weakness,
4. <2.5 mEq/L – cramps, parasthesias,
ileus, tetany, rhabdomyolisis, A-V
block
10/12/17 06:00 36

Hypokalemia
 Causes
• Gastrointestinal losses
• Systemic alkalosis
• Diabetic ketoacidosis
• Diuretic therapy
• Sympathetic nervous system stimulation
• Administration of beta-adrenergic receptor
agonists
10/12/17 06:00 37

Hyperkalemia
1. Defined as a serum [K+] greater than 4.6 mEq/L
2. Changes in cellular transmembrane potentials can lead to
lethal cardiac arrhythmias
3. Most often associated with renal impairment coupled with
exogenous K+ administration or drugs that increase K+
4. Transcellular shifts – acidosis, succinylcholine, insulin
deficiency, massive tissue destruction
5. Massive blood transfusions
6. Pseudohyperkalemia - Thrombocytosis, hemolysis,
leukocytosis
7. Urine K+ excretion rate can be used to determine exact
cause of hyperkalemia
10/12/17 06:00 38

Hyperkalemia
1. Drugs causing hyperkalemia – K+
sparing diruetics, ACEI, NSAIDs,
Heparin, Cyclosporin, Tacrolimus,
Bactrim
2. ECG Changes
A. 5.5 – 6.5 mEq/L – peaked T-waves
B. 6.5 – 7.5 mEq/L – loss of P-waves
C. > 8.0 mEq/L – widened QRS
10/12/17 06:00 39

Hyperkalemia
1. Inadequate intake
2. Increased excretion – diarrhea, diuretics,
alkalosis, glucocorticoids, RTA
3. Transcellular shifts – beta-agonists,
theophylline, insulin, hyperthyroidism,
barium
4. Replace no faster than 20 mEq/H
peripherally and 100 mEq/H centrally
10/12/17 06:00 40

 Step 1 Sna > 145 => Hypernatremia
Sna< 135 => Hyponatremia
 Step 2 Calculate Serum Osmolarity
Hypernatremia = Hyperosmolar
Hyponatremia = Is it Hypoosmolar, Isoosmolar or
Hyperosmolar
 Step 3 Does calculated serum osmolarity agree with
measured serum osmolarity to within 10 meq/l.
 Step 4 Determine ECV status euvolemic, hypovolemic, or
hypervolemic .
 Step 5 Obtain Urine Sodium and Urine Osmolarity.
Is Urine sodium <or> 20 meq/l ?
Is Urine osmolarity <or> 400 meq/l ?
10/12/17 06:00
41

Hypomagnesemia
 Serum magnesium less than 1.5mEq/L
 Causes:
• Inadequate intake of magnesium
• TPN ( Total parenteral nutrition)
• Gastrointestinal losses
• Pancreatitis
• Parathyroid hormone disorders
• Hyperaldosteronism
• Ketoacidosis
• Chronic alcoholism
10/12/17 06:00 42

Hypocalcemia
 Causes:
• Decreased serum albumin concentration
• Chelation of calcium by citrate
• Rhabdomyolysis
• Hypoparathyroidism
• Pancreatitis
• Renal failure
10/12/17 06:00 43

Clinical Manifestations of Hypocalcemia
 Neuromuscular irritability
• Tetany
• Laryngospasm
• Hyperactive deep tendon reflexes
 Weakness
 Vasodilation
 Myocardial dysfunction
 Bradycardia
 Heart block
10/12/17 06:00 44

Hypercalcemia
 Causes:
• Calcium mobilization from bone due to
immobility
• Tumors
• Hyperparathyroidism
10/12/17 06:00 45

Clinical Manifestations of Hypercalcemia
 Anorexia
 Nausea
 Constipation
 Cognitive depression
 EKG changes
• Prolonged PR interval
• Shortened QT interval
• PVC’s
10/12/17 06:00 46

Factors influencing intraoperative fluid management:
 Patient’s perioperative fluid status
 Co-existing disease
 Intra-operative fluid shifts
 Intra-operative blood loss
 Selection of appropriate fluids for replacement of intra-
operative losses
10/12/17 06:00 47

The Patient
51-year-old male with acutely
decompensated schizo-affective disorder
was readmitted 1 day after discharge to
Psychiatry unit involuntarily for increasing
agitation and psychosis
History of noncompliance with medications
(Lithium 1200 mg, Clozaril 375 mg,
Modafinil 400 mg, Synthroid 75 mcg) all of
which were restarted
10/12/17 06:00 48

Deterioration during
hospitalization
Patient was in and out of locked seclusion
due to violent behavior with subsequent
poor oral intake
CBC, Chem 7 and CK were done after 4
days because staff felt that patient’s mental
status has worsened and dystonia might be
present
Serum sodium was noted to be high, and a
general medicine consult was requested
10/12/17 06:00 49

Physical Exam
BP: 160/82, P: 92, T: 37; orthostatic to
110/60 previous evening per nursing note
Tongue and oral mucosa: dry
Skin: poor turgor and tenting
Cor: JVP-flat, normal heart sounds
Lungs: Clear. Abdomen, non-tender, BS +
GU: incontinent of urine in diaper
Neuro: limited exam, incoherent, psychotic,
agitated, in 4 point leather restraints
10/12/17 06:00 50

Initial Lab Results
 Sodium = 154
 Potassium = 4.4
 Chloride = 115
 HCO3 = 26
 BUN = 27
 Creatinine = 1.4
 Calcium = 10.1
 Glucose = 100
 Urine Na+
= 41
 Urine Osmolality = 492
 Plasma Osmolality = 31510/12/17 06:00 51

What is the cause of his
hypernatremia?
10/12/17 06:00 52

What is the hypernatremia due
to in our patient?
Poor water/oral intake due to psychosis
Acquired partial nephrogenic DI due to
Lithium (suggested by low urine osmolality
relative to high serum osmolality)
Increased insensible loss due to agitation,
and hyperventilation
?? Renal loss of sodium-urine Na+
41
10/12/17 06:00 53

Flame photometers
10/12/17 06:00 54

Components of a modern Flame
Photometer
10/12/17 06:00 55

Atomic Absorption
Spectrophotometer
10/12/17 06:00
56

Atomic Absorption Spectrometry
10/12/17 06:00 57

Ion selective electrodes
10/12/17 06:00 59

Potentiometric sensor
10/12/17 06:00 60

Ion selective electrodes
1. Glass-membrane electrodes
2. Solid-state-membrane
electrodes
3. Liquid-membrane electrodes
4. Modified-membrane electrodes
10/12/17 06:00 61

Electrolyte Disorders

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