Transcript Diagnosis and Management of Electrolyte Abnormalities

Diagnosis and
Management of
Common Electrolyte
Disorders
Eric I. Rosenberg, MD, MSPH, FACP
Rev 11/06 electrolytes1106
Objectives
To discuss diagnostic and
therapeutic strategies for:
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2.
3.
4.
Hyponatremia
Hypernatremia
Hyperkalemia
Hypokalemia
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Case 1
• 60 year old man
• “Admit for weakness and
hyponatremia”
• [Na+] 120 mg/dL
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Clinical Evaluation
• History
– Symptomatic?
– Predisposed?
– Medications? IVF’s?
• Physical
– Volume status?
• Labs
– Confirm (if unusually abnormal)
– Context
– Additional diagnostic tests
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Case 1 (cont’d)
• Nausea, weak, confused x 1 week
• HTN, CHF
• JVD, crackles (rales), edema
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Na+ 120 mEq/L
BUN 93 mg/dL
Cr 3 mg/dL
Glucose 135 mg/dL
Albumin 2.9 mg/dL
Plasma osm 252 mOsm/kg
Urine osm 690 mOsm/kg
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“Choose the most
appropriate treatment”
• 3% I.V. NaCl
• 0.9% I.V. NaCl
• 50 mg hydrochlorothiazide daily
• Salt and water restriction
• Demeclocycline
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Differential diagnosis
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Hyponatremia usually
reflects excessive H20
Common Differential Dx
• Decreased Water
Excretion
GFR
Kidney perfusion
– SIADH
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•
•
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Addison’s Disease
Malnutrition
*Pseudohyponatremia
±Psychogenic (>1 L /
hour)
*100mg/dL glucose increase  1.6 mEq/L [Na] decrease
± Urine specific gravity < 1.003
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COMMON CAUSES of HYPONATREMIA
Volume Status
Low
Normal
High
GI/Renal Losses
Diuretics
SIADH
Hypothyroidism
Adrenal Insufficiency
Thiazide
CHF
Nephrotic Syndrome
Cirrhotic
Hypoosmolar (serum osm <270)
Hypoosmolar
Hypoosmolar
Renal: Urine [Na] > 20
GI: Urine [Na] < 20
SIADH: Urine Osmolality > 100*)
Renal: Urine [Na] > 20
Non-Renal: Urine [Na] <20
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2.
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History: predisposing features
Exam: volume status (including orthostatics supine/standing)
BMP; Urinalysis; Serum Osmolality; (Urine Sodium; Urine Osmolality)
Head C.T. (if symptomatic)
Other imaging/labs to evaluate CV, Renal, Endocrine systems as needed11
Complications of
Treating Hyponatremia
• Delayed treatment
– Cerebral edema
– Permanent neurological injury
– Death
• Inappropriately rapid treatment
– Cerebral dehydration/demyelination
– Permanent neurological injury
– Death
• Inappropriate treatment
– Failure to improve  morbidity
– Delayed improvement  morbidity
– Further deterioration
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Common Treatment
Options
• Water restriction
• Diuresis (with loop diuretic)
• Volume infusion (with crystalloid)
• Hypertonic saline
• Demeclocycline
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What if he had cerebral
edema?
1. Correct [Na+] to 125-130mEq/L
to temporarily relieve edema
2. [Na+] should NOT increase by
more than 10-12 mEq/L in 1st 24
hours
3. Slow/Stop infusion as soon as
symptoms improve
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3% NaCl Calculation
[Na+] = 116 mEq/L
Goal [Na+] = 125 mEq/L at 24 hours
Amount of Na+ to be given as 3% infusion:
= [Serum Na+ (desired) – Serum Na+(measured) ] (TBW)
= [125 – 116] [(0.5)(60kg)]
= 270 mEq Na+
3% saline = 513 mEq sodium/L
270/513 = 0.5 L = 500 ml over 24 hrs.
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Hyponatremia: Key
Points
• 127 mEq/L
• Excess water
• If symptomatic,
treat rapidly
• Slowly correct [Na+]
*towards* normal
• Find the underlying
cause
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Case 2
• 40 y/o woman s/p hypertensive
brain hemorrhage 2 weeks ago.
• This morning she’s less responsive.
• What may have caused this new
problem?
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• Stuporous
• BP 150/70, HR 94
• Dry mouth, poor turgor
• Na 160 mEq/L; K 2.8 mEq/L;
HCO3: 18 mEq/L; Cl 137 mEq/L
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Differential diagnosis
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Hypernatremia usually
reflects insufficient H20
Differential Diagnosis
• Lack of water
• Severe diarrhea
• Severe burns
• H20 excretion
–Osmotic diuresis
•
H20 conservation
–Diabetes insipidus
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Guidelines for
Hypernatremia Rx
• Determine and treat likely cause(s)
• Most common error is
“underguesstimation” of water deficit:
TBW x ([Na+(measured)] – [Na+(desired) ])/[Na+
(desired)]
• Replace H20 enterally if possible
• Frequent monitoring
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Sodium Content of
IVF’s (mEq/L)
• 3% saline: 513
• 0.9% (normal) saline: 154
• Ringer’s Lactate: 130
• Half Normal (0.45%) saline: 77
• 5% Dextrose (D5W): 0
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Hypernatremia: Key
Points
• [Na+] >145
mEq/L
• Net water loss
• Calculate the
water deficit
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Case 3
• 29 y/o man with severe muscle
weakness.
• No vomiting or diarrhea.
• Normal physical exam.
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• Na = 141 mEq/L
• K = 1.4 mEq/L
• Cl = 116 mEq/L
• HCO3- = 11 mEq/L
• pH = 7.25, pCO2 = 21 mmHg
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Consequences of
Hypokalemia [K] <3
• Neuromuscular manifestations
– Weakness, fatigue, rhabdomyolysis,
myonecrosis, respiratory failure
• GI symptoms
– Constipation, ileus
• Nephrogenic Diabetes Insipidus
• Dysrhythmias (if heart disease)
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Common Causes of
Hypokalemia
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Malnutrition/NPO
Diarrhea (100 mEq/L)
Vomiting (volume depletion)
DRUGS
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Thiazides (stimulate excretion)
Amphotericin B
Penicillins
Gentamicin
Foscarnet
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“Choose the most likely
diagnosis”
• Bartter’s syndrome
• Laxative abuse
• Primary aldosteronism
• Diuretic abuse
• Distal renal tubular acidosis
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Less Common Causes
• Hormonal
– Primary hyperaldosteronism
• Adenomas, hyperplasia, ectopic ACTH, ectopic
mineralocorticoid (licorice, chaw)
– Secondary hyperaldosteronism
• Renal hypoperfusion (CHF, RAS, severe HTN)
• Renin-secreting tumor
• Renal tubular disease
– Type 1 or 2 RTA
– Bartter’s syndrome (metabolic alkalosis, polyuria)
– Chronic magnesium depletion
• Laxative abuse (metabolic alkalosis)
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Hypokalemia Rx
• Recognize likely total body depletion
– 1 mEq/L decrease = 150-400mEq total
deficiency
• Gradual oral replacement
• I.V. replacement if serum level less than
3 mEq/L
• Check & Replace magnesium
• Consider telemetry
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Hypokalemia: Key Points
• [K+] < 3.5: review
medications, review
health status
• [K+] < 3:
intervention
• Recognize Mg+ is
cofactor
• Renal/CV monitoring
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Case 4
• 59 y/o man with 3-days malaise,
decreased mental acuity and
responsiveness, slurred speech.
• ESRD on hemodialysis; HTN, DM,
Hypothyroidism
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• Disoriented and lethargic
• BP (supine) 148/79mmHg, HR
101/min (supine) RR 26/min, T
37.7oC.
• Mucous membranes are moist,
neck veins are distended. Bilateral
crackles and wheezes. Loud S4.
3+ peripheral edema.
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What is the next most appropriate
step in managing this patient?
A. Begin I.V. infusion of normal saline for
volume repletion
B. Administer 1 ampule dextrose and 10
units insulin I.V. for hyperkalemia
C. Transfer to the ICU and perform
emergent peritoneal dialysis
D. Transfer to the ICU and perform
emergent hemodialysis
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“Dialysis machine
available in 20 minutes”
Emergency Treatment
[K] > 6 mEq/L
• “STAT” ECG
• “STAT” repeat [K+]
• Give IV Calcium
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Additional Rx
• More IV Calcium
• Glucose and Insulin
• Bicarbonate
• Inhaled Beta-2 agonists
• Sodium polystyrene sulfonate
(Kayexalate®)
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Severe hyperkalemia is
usually preceded by
moderate, uncorrected
hyperkalemia
Differential Dx
• Renal Failure (GFR < 10 ml/min)
• Extra Renal Causes
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Metabolic acidosis
Cell lysis (chemotherapy, trauma)
Salt substitutes, ACE-I/ARB,
Addison’s Disease
Pseudo (coagulated RBC’s/platelets)
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Hyperkalemia: Key Points
• K>4.5: caution
with medications,
& monitor
• K>5.5: intervene
• Calcium (not
kayexalate) is 1st
line
• Check ECG
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SUMMARY
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Construct your differential
Know the complications of therapy
Know the implications of lack of therapy
Calculate water/electrolyte needs
… But repeated and frequent monitoring
is most important.
• Electrolyte disorders may be a
diagnostic clue or an expected
consequence of therapy
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