Electrolyte Disorders

1
Electrolyte Disorders

• Resident Rounds
• Aric Storck
• February 26, 2004

2
Case 1

• 75 yo woman
• orthostatic presyncope x 2 days
• diarrhea x 1 week
• drinking 2-3 litres of tea a day
• PMHx
• HTN
• Meds
• HCTZ 25 mg po od

3

• O/E
• JVP ASA
• significant orthostatic drop in BP
• lab
• Na 128
• K 3.1
• Cr 125

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HyponatremiaClinical SSx

• Severity depends on absolute value AND rate of
  decrease

Source Yeates K, et al. CMAJ 2004170(3)365-9
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Symptoms
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Approach to hyponatremia
Hyponatremia
Hypo-osmolar
Iso-osmolar
Hyper-osmolar

• Normal ECF osmolality
• Increased serum solids, lipids (nephrotic
  syndrome) , protein (multiple myeloma)

• Vast majority

• Glucose / mannitol
• Draws H2O into ECF

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Hypo-osmolar hyponatremia
Non-hypovolemic
Hypovolemic
GI Losses
Renal Losses
Skin Losses

• Vommitting
• diarrhea
• bleeding
• obstruction

SIADH
Edematous States

• Diuretics
• hypoaldo
• salt-wasting neph

• Burns
• GPP/
• erythroderma

CHF nephrotic Synd cirrhosis
CNS Disease Pulmonary Drugs
Slide courtesy of Adam Oster
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Hypovolemic Hyponatremia

• Loss Na gt Loss H2O
• ADH released (low ECF)
• increases tubular reabsorption of H2O
• low urine volume
• Renin released (low renal perfusion)
• kidneys retain sodium
• urine sodium low (lt20 mmol/L)

9

• What caused our patients hyponatremia?
• GI losses
• HCTZ (impairs excretion of free water)
• as ECF decreases kidney exchanges K for Na to
  maintain volume - thus low K

10

• How will you treat our patient
• d/c HCTZ
• oral rehydration salts
• IV NS KCl until no further postural drop
• oral sodium and K
• recheck lytes in a few days

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Case 2

• 58 yo man
• small cell lung cancer
• confusion lethargy x 2 days
• No Meds

• O/E
• JVP 3cm
• MMM
• no ascites / no edema
• no sign of hypothyroidism or hypoadrenalism

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lab

• Na 108
• K 3.9
• Cr 44
• urine Na 44

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Euvolemic HyponatremiaDDx

• SIADH
• hypothyroidism
• adrenal insufficiency
• psychogenic polydipsia

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SIADH

• Diagnosis
• clinically euvolemic
• normal renal function
• normal thyroid (TSH)
• normal adrenal (cortisol stim test)
• no medications known to cause SIADH-like syndrome

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SIADHcauses
Source Yeates K, et al. CMAJ 2004170(3)365-9
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SIADH - Treatment

• acute
• hypertonic saline
• goal to increase Na by 5 over 12 hours or until
  asymptomatic
• fluid restriction
• 750-1500 ml/d
• goal to increase Na by 5 over 12 hours
• chronic
• fluid restriction
• Li (inhibits renal effects of ADH)
• demeclocycline 600 mg po od

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What happens if you use normal saline?

• More water retained than Na
• worsening hyponatremia

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How do you calculate amount of fluid needed?
Source Adrogue H, et al. NEJM 2000
342(1)1581--1589.
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Sample calculation

• Change Na per litre 3 HTS
• (513-108) / (0.6x60 1)
• 10.8 mmol
• thus 0.46 litres (5/10.8) over 12 hours
• 38ml/h x 12 hours

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Case 3

• 45 year old woman
• alcoholic, HCV, end stage hepatic disease
• gross ascites and peripheral edema
• Na 125

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Hypervolemic hyponatremia

• Increased ECF
• CHF
• cirrhosis / ascites
• nephrotic syndrome
• low effective circulating volume
• body retains Na and H20
• low urine Na (lt20)
• Treatment
• Na and free water restriction

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Source Yeates K, et al. CMAJ 2004170(3)365-9
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Pseudohyponatremia

• falsely low Na due to
• high serum protein concentration
• high serum lipids
• was an issue w/ flame photometry but not w/
  potentiometric measurment techniques

Slide courtesy of Moritz Haager
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Redistributive Hyponatremia

• dilutional picture due to presence of excess
  osmotically active substances drawing water out
  of cells into extracellular space
• Hyperglycemia (e.g. DKA)
• Correction 3mmol Na decrease for every 10
  mmol increase in glucose
• Mannitol

Slide courtesy of Moritz Haager
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Case 4

• Your med student saw the pt and w/o discussing
  with you ordered a 1 L bolus of NS X 2 and then
  200 cc/h
• The pts Na corrects to 138 by next AM
• Pt is sent home asymptomatic 36 hrs after
  admission
• Comes back 3 days later unable to stand,
  confused, with slurred speech
• Whats going on?

Slide courtesy of Moritz Haager
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CPM central pontine myelinolysis

• Pathophysiology
• Acute non-inflammatory demyelination in basis
  pontis and other CNS sites (in 10)
• Mechanism unknown felt to occur due to rapid
  changes in cell volume
• Actual incidence is unknown
• Risk factors
• Na lt120 mEq/L for gt 48 hrs
• Aggressive IV resuscitation w/ hypertonic saline
• Most cases occurred with rates of correction gt 12
  mmol/L /24 hrs
• Hypernatremia during treatment

Slide courtesy of Moritz Haager
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CPM central pontine myelinolysis

• Clinical Features
• Usually neurologic deterioration 48-72 hrs after
  rapid Na correction
• Confusion, horizontal gaze paralysis, spastic
  quadriplegia, pseudobulbar palsy, encephalopathy
  coma, locked-in syndrome
• Dx
• MRI
• Tx
• supportive

Slide courtesy of Moritz Haager
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Treatmentsummary

• Hypovolemic hyponatremia
• Correct with NS (0.9) which is mildly hypertonic
  compared to pts serum
• Euvolemic hyponatremia
• Restrict free water intake
• Identify underlying cause
• SIADH
• Giving normal saline will worsen condition due to
  free water retention
• Can Tx with lithium and demeclocycline ? inhibit
  action of ADH
• Hypervolemic hyponatremia
• Restrict free water intake
• /- diuretics ? may worsen due to further Na
  loss
• dialysis if large amount of fluid needs to be
  taken off

Slide courtesy of M Haager
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Hyponatremia
Fluid overloaded (excess water gt excess Na)
Normovolemic (excess total body water but no
edema)
Dry
Source of Sodium loss?

• SIADH
• Drugs
• Glucocorticoid
• deficiency
• Hypothyroidism
• Pain / emotion

• Nephrotic
• Syndrome
• Cirrhosis
• CHF

Acute / Chronic Renal Failure
Renal -Diuretics -Adrenal insufficiency -Salt-was
ting nephritis -Bicarbonate loss -RTA
-metabolic alkalosis -ketonuria -Osmotic
diuresis -glucose -mannitol
Extra-renal losses -GI losses -Third spacing
Urine Na gt20 mmol/L
Urine Na lt10 mmol/L
Urine Na gt20 mmol/L
Urine Na lt10 mmol/L
Urine Na gt20 mmol/L
Normal Saline
Water restriction
Slide courtesy of M Haager
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Case 5

• 93 year old man from nursing home
• demented
• not eating well
• less perky than usual - in ER to be checked out
• O/E
• JVP down, dry mouth
• 97 16 87/53 99 37.3
• Na 157

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(No Transcript)
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Hypernatremia

• Signs
• lethargy
• stupor
• coma
• muscle twitching
• hyperreflexia
• spasticity
• tremor
• ataxia
• focal neurological signs

• Symptoms
• anorexia
• N/V
• fatigue
• irritable

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Causes of Hypernatremia

• Gain in Na
• exogenous Na intake
• NaCl
• NaHCO3
• hypertonic NS
• salt water drowning
• increased Na reabsorption
• hyperaldosteronism
• cushings disease
• exogenous corticosteroids
• congenital adrenal hyperplasia

• Reduced H2O intake
• disorders of thirst
• cant get H20
• Increased H2O loss
• GI
• VD
• NG
• 3rd spacing
• renal
• DI
• osmotic diuresis
• post-obstructive diuresis
• dermal
• burns
• perspiration

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Causes of DI

• Nephrogenic
• congenital renal disorders
• obstructive uropathy
• polycystic disease
• drugs
• amphotericin B
• phenytoin
• Li
• aminoglycosides
• methoxyflurane

• Central
• idiopathic
• head trauma
• cerebral hemorrhage
• suprasellar infection
• granulomatous disorders
• Systemic diseases
• sickle cell
• sarcoidosis
• amyloidosis

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Management of hypernatremia

• Hypovolemic
• goal restore volume deficits
• 0.9 NS
• Euvolemic
• DI
• oral fluids
• hypotonic saline (0.45)
• vasopressin

• Hypervolemic
• increase renal sodium excretion gt H20
• diuretics /- hypotonic saline
• may need dialysis

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Calculation of water deficit

• Water deficit
• Weight (kg) x
• ( Normal Na / Measured Na - 1 )

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Case 6

• 53 year old man
• DM 1, chronic renal failure
• presents via EMS from home
• Wife tells you that he has had N/V/D for the last
  4 days with decreased po intake.

• O/E
• 140, 89/59, 26, 94, 37.3
• JVP down, dry MM
• Slightly tender abdomen
• What would you like to order?

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lab

• CBC
• Hb 146
• WBC 35
• neutrophils 30
• 0.3 bands
• Platelets 223

• Lytes
• Na 133
• K 7.4
• HCO3 4
• Cl 97
• Cr 223
• glucose 43

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Case 6ECG
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HyperkalemiaClinical Features

• Cardiac
• 2/3 degree heart block
• wide complex tachycardias
• VF
• asystole

• ECG progression
• peaked T waves
• loss of P waves
• prolonged PR interval
• widening of QRS
• sine wave pattern
• ventricular fibrillation
• asystole

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HyperkalemiaNeurological SSx

• Non-specific
• muscle cramps
• weakness
• paralysis
• paresthesias
• tetany
• focal neurological deficits

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Potassiuma precisely controlled cation

• Mostly intracellular
• Precise transcellular gradients required for
  neuronal transmission and cardiac conduction
• Also important in acid-base balance and
  buffering.
• K/H pump

• Extracellular K controlled by
• serum pH
• change in pH of 0.1
• 0.6mEq change in K
• aldosterone
• insulin
• catecholamines

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Hyperkalemia Mechanisms
CELLULAR INJURY
INCREASED INTAKE
TRANSCELLULAR SHIFT
IMPAIRED EXCRETION
RENAL FAILURE
NON RENAL FAILURE
Slide courtesy of A. Oster
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Hyperkalemia - etiology

• Transcellular shifts
• acidosis
• insulin deficient
• drugs
• B-Blockers
• sux
• digitalis
• cellular injury
• rhabdomyolysis
• tumour lysis syndrome
• crush/burn

• pseudohyperkalemia
• hemolysis
• increased intake
• impaired renal excretion
• renal failure
• hypoaldosteronism
• K-sparing diuretics

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Management Principles

• Cardiac monitoring
• stabilize myocardium
• shift K into cells
• decrease GI absorption
• treat underlying cause

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Immediate ManagementCalcium

• mechanism
• antagonises K and stabilizes myocardium
• indications
• dysrhythmia
• hypotension
• ECG changes
• onset
• 0-5 minutes
• duration
• 20-40 minutes
• dose
• 5-30ml 10 calcium gluconate IV

Slide courtesy of A. Oster
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Immediate ManagementVentolin

• Mechanism
• shifts K into cells
• onset
• 15 minutes
• duration
• 2-4 hours
• dose
• 5-10mg neb repeat prn

Slide courtesy of A. Oster
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Immediate ManagementGlucose and Insulin

• mechanism
• shifts K into cells
• onset
• 15 minutes
• duration
• 4-6 hours
• dose
• 10-20 units of R
• 1 amp D50W
• (no D50W if hyperglycemic)

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Immediate Managementbicarbonate

• mechanism
• shifts K into cells
• only works if acidotic
• onset
• 15 minutes
• duration
• 2 hours

• dose
• 1 amp (44 meq) IV push over 5 minutes
• beware if
• hypertonic
• hypernatremic
• alkalotic

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Delayed TherapyExchange Resins

• kayelalate (polystyrene sulfonate)
• mechanism
• ion exchange resin
• removes K from body
• onset
• 1 hour
• duration
• 1-3 hours
• dose
• 1g binds 1mEq of K
• oral or rectal
• 20g in 70 sorbitol po (Rosen)
• 30g pr retained for 30 minutes

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Delayed Therapyhemodialysis

• Mechanism
• removes K from blood
• can remove 200-300 meq
• Indications
• renal failure
• unstable patient unresponsive to other treatment

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Case 6K 7.4
Slide courtesy of A. Oster
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Case 6 K6.2
Slide courtesy of A. Oster
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Case 6K 5.5
Slide courtesy of A. Oster
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Case 7

• General surgery rotation
• 0330 - you are awakened from a sound sleep by a
  nurse who tells you that Mr. Xs potassium is
  only 3.0.
• Do you care?
• Why do you care?
• What are you going to do about it?

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HypokalemiaSpectrum of Symptoms

• Asymptomatic
• K 3-3.5
• Neuromuscular
• K usually lt 2.5
• lethargy
• confusion
• fasciculations
• weakness
• decreased DTRs
• paralysis (Klt2)

• Cardiovascular
• usually no symptoms in patients without heart
  disease
• palpitations
• ectopy
• dysrhythmias
• 1 - 2 degree HB
• atrial fibrillation
• ventricular fibrillation

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• GI
• impairs intestinal smooth muscle
• N/V
• paralytic ileus
• Renal
• polyuria
• polydipsia

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Approach
DECREASED INTAKE
TRANSCELLULAR SHIFT
INCREASED LOSSES
RENAL
GI
Slide courtesy A. Oster
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Hypokalemia

• Decreased Intake
• decreased dietary intake
• decreased absorption
• Transcellular Shifts
• alkalosis
• insulin
• B2 agonists
• eg ventolin - lowers K 0.4 mmol/L x 4 hours
• coffee

• Increased Loss
• renal
• hyperaldosteronism
• renal tubular defects
• mineralocorticoids
• glucocorticoids (alter GFR)
• diuretics
• drugs
• GI
• N/V/D
• Skin
• burns
• perspiration

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His ECG...
Slide courtesy A. Oster
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Hypokalemia

• ECG findings
• small or absent T waves
• prominent U waves
• ST segment depression

Slide courtesy A. Oster
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How will you treat him?

• Potassium is an intracellular ion
• 1 mEq/L decrease in serum K may equal up to 370
  mEq total body deficit
• 50 of administered K excreted in urine -
  therefore several days to correct deficit

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• Oral
• K-Dur (20mmol/tab)
• KCl elixir(20mmol/15ml)
• K-Phos(4.4mmol/ml)
• useful if hypophosphatemic
• K-Citrate (0.9mmol/ml)
• useful in RTA

• IV
• KCl (10/20/40mmol/100cc)
• 10-20mEq/h
• gt20mEq/h requires central line and cardiac
  monitor
• S/Es
• transient hyperkalemia
• burning at IV site

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Hypomagnesemia

• Magnesium required in Na-K ATP-ase
• hypomag often co-exists with hypokalemia
• Mg must be corrected along with K
• Cofactor in PTH metabolism
• often coexists with low Ca

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Hypomagnesemia

• Diuretic use
• thiazide and loop diuretics
• decrease Mg 25-50
• EtOH abuse
• 30-80
• Renal losses
• GI losses
• V/D
• short bowel
• pancreatitis

• Endocrine disorders
• DM
• hyperaldosteronism
• hyperthyroidism
• Pregnancy
• Drugs
• aminoglycosides, B-agonists, cyclosporine,
  pentamidine, theophylline
• Congenital disorders

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Hypomagnesemiaclinical features

• Non-specific
• Neuromuscular
• weakness
• tremor
• hyperreflexia
• Chvostek/Trousseau
• seizures
• coma

• Cardiac
• supraventricular dysrhythmias
• ventricular dysrhythmias
• ECG
• non-specific
• long PR/QRS/QT
• ST-T abnormalities
• flattened T
• Uwave

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HypomagnesemiaManagement

• Treat if
• Magnesium lt 1.2 mg/dl
• or, symptomatic

• IV
• Magnesium sulfate
• 1g 8.3mEq magnesium
• Oral
• Magnesium Rougier
• multiple others
• cause diarrhea

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Hypermagnesemia

• Very rare . especially in ER
• kidneys can excrete gt6g / day
• generally
• iatrogenic
• renally insufficient

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HypermagnesemiaClinical Features

• gt3 mg/dl
• N/V
• weakness
• gt4mg/dl
• hyporeflexia
• loss of DTRs

• gt5-6mg/dl
• hypotension
• ECG changes
• QRS widenine
• QT/PR prolongation
• conduction abnormalities
• gt9mg/dl
• repiratory depression
• coma
• complete heart block

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HypermagnesemiaTreatment

• Mild symptoms normal renal function
• Observe
• Moderate symptoms
• IV normal saline furosemide
• watch K

• Severe symptoms
• IV Calcium
• antagonizes membrane effects of Mg
• reverses respiratory depression/dysrhytmias, etc
• Dialysis
• refractory symptoms
• renal failure

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Case 8

• 55 woman with metastatic breast cancer
• Increasing weakness and confusion x 24 hours
• Ataxic this morning
• Headache
• Thirsty
• Vitals
• 110 18 100/80 92 37.0
• O/E
• alert but disoriented and confused, GCS 15
• otherwise unremarkable

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Case 8

• Labs
• CBC
• normal
• electrolytes
• normal
• Calcium 4.5
• Albumin 30

• How do you correct Ca for albumin?
• Add 0.2 for every 10 units albumin is below 40
• ie 47

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Case 8ECG

• Characteristic changes
• Short QT
• prolongation or PR
• QRS widening
• Occasionally see
• sinus bradycardia
• BBB
• AV block
• cardiac arrest

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Calcium Metabolism

• 1200g Ca in body
• 99 in bone
• 1 in serum
• 60 protein bound
• 40 free

• parathyroid hormone
• ? bone resorption
• ? renal Ca reabsorption
• ? renal conversion vitamin D to 1,25DHCC)
• ? renal phosphate excretion
• calcitonin
• decreases osteoclastic activity and enhances
  skeletal deposition

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HypercalcemiaEtiology

• Most (90)
• Primary hyperparathyroidism
• Malignancies

• Others
• medications
• thiazides
• Li
• Vitamin D toxicity
• Ca ingestion
• granulomatous disease
• other endocrine disorders

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HypercalcemiaClinical Features

• Neurologic
• fatigue, weakness
• confusion, lethargy
• ataxia
• coma
• hypotonia
• CV
• hypertension
• sinus bradycardia
• AV block
• ECG abnormalities (short QT, BBB)

• Renal
• polyuria, polydipsia
• pre-renal azotemia
• nephrolithiasis
• nephrocalcinosis
• GI
• N/V
• pancreatitis
• constipation
• ileus

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HypercalcemiaTreatment Principles

• restore intravascular volume
• Serum calcium will decrease with hydration
• increase renal calcium elimination
• hydration
• fursosemide 40-80mg iv q6-8h
• AVOID thiazides

• reduction of osteoclastic activity
• Etidronate/Pamidronate
• Plicamycin
• calcitonin 4U/kg sc q12h
• treatment of primary disorder
• parathyroidectomy
• treat malignancy
• withdrawal of meds

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Case 9

• 52 year old woman
• HTN
• B-Blocker, thiazide
• diarrhea x 1 week
• tingling around mouth and in fingers
• cramps in arms and legs

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When taking her blood pressure
Source Meininger et al. NEJM 2000343 (25) 1855
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Case 9ECG
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HypocalcemiaEtiology

• ? PTH
• PTH insufficiency
• primary
• secondary
• neck surgery
• Mg disorders
• pancreatitis
• drugs

• ? PTH
• Vitamin D insufficiency
• malnutrition
• malabsorption
• hepatic/renal disease
• Calcium chelation
• hyperphosphatemia
• citrate
• alkalosis
• fluoride poisoning

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HypocalcemiaClinical Features

• Neuromuscular
• confusion/anxiety
• paresthesias
• weakness
• spasms
• tetany
• Chvostek/Trousseau
• hyperreflexia
• seizures

• CV
• bradycardia
• decreased contractility
• hypotension
• CHF
• ECG
• QT prolongation

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Hypocalcemia

• Management
• IV calcium chloride
• 10ml amps of 10
• 360mg elemental Ca
• IV calcium gluconate
• 10ml amps of 10
• 93mg elemental Ca

• recommended initial adult dose is 100-300mg
• pediatric dose is 0.5-1.0mg/kg of Ca gluconate
• lasts 2hours
• consider an infusion
• S/Es
• HTN
• N/V
• bradycardia/HB
• tissue necrosis if interstitial

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the end