Fluid and Electrolyte
Abnormalities
Dr. Shreedhar Paudel
April, 2009
Water Steady State
• Amount Ingested = Amount Eliminated
Body Fluids and Fluid Compartments
• The percentage of total body water: 45-75%
• Intracellular compartment
– 2/3 of body water (40% body weight)
• Extracellular compartment
– 1/3 of body water (20% body weight)
• the blood plasma (water=4.5% body weight)
• interstitial fluid and lymph (water=15% body
weight)
• transcellular fluids: e.g. cerebrospinal fluid,
aqueous humor (1.5% BW)
• Distribution of substances within the body is NOT
HOMOGENEOUS
Body Water Distribution
• Individual variability (lean body mass)
– 55 - 60% of body weight in adult males
– 50 - 55% of body weight in adult female
– ~42 L For a 70 Kg man
RBC
Input
PLASMA WATER
5%
3L
ECF
20%
CELL WATER
40%
28 L
INTERSTITIAL
FLUID
COMPARTMENT
15%
10 L
TRANSCELLULAR WATER
1%
1L
14 L
Goals
• Review of common electrolyte abnormalities
– Normal ranges
– Clinical manifestations of hypo- or hyper- states
– Causes
– Treatment options
Hyponatremia
• Sodium: Normal 135 – 145 mEq / L
• Symptoms usually begin <120 mEq/L
– Nausea
– Lethargy
– Muscle cramp
– Psychosis
– Seizure
– Coma
– Death
Hyponatremia
• Diagnosis based on assessment of serum
osmolality and volume status
• Serum Osmolality
– Osmolality (calculated) =
2 (Na) + Glucose / 18 + BUN /2.8
Hyponatremia
• Normal Osmolality (280 – 295 mOsm / kg)
• Isotonic pseudohyponatremia
• Hyperproteinemia (>10 mg / dl)
• Hyperlipidemia (severe)
Hyponatremia
• High Osmolality (>295 mosm / kg)
• Hypertonic hyponatremia
– Hyperglycemia
Na: 1.6mEq / liter decrease per
100 mg/dl increase in glucose
--Mannitol excess
--Glycerol therapy
Hyponatremia
• Low serum osmolality (<280 mOsm / kg)
• Hypotonic hyponatremia
--Need to assess volume status next in these
patients
Hypotonic hyponatremia
• Hypovolemia
– GI losses
– Renal losses plus excess water ingestion
– Third space losses
Tx: Isotonic saline
Hypotonic Hyponatremia
• Hypervolemia
– CHF
– Liver disease
– Nephrotic syndrome
– CKD
Urine Na: < 20 mEq /liter except in CKD
Tx: Salt restriction / water restriction / diuretics
Hypotonic Hyponatremia
• Isovolemia
– Glucocorticoid insufficiency
– Hypothyroidism
– Psychogenic polydipsia
– Medications (amitriptyline / cyclophosphamide /
carbamazepine / morphine)
– SIADH
– Nausea / pain / emotional stress
– Diuretic use with potassium depletion
Isovolemic Hypotonic Hyponatremia
• SIADH
– Syndrome of inappropriate antidiuretic hormone
• Hypotonic hyponatremia
• Clinical euvolemia
• Inappropriately elevated urine osmolality (>200) in face
of low serum osmolality
• Urine Na >20 mEq / liter
• Normal renal function / TSH / cortisol
SIADH
• Acute tx
– Severe hyponatremia (<110 mEq / liter)
• NS with 20 – 40 mEq / liter KCL
• IV lasix
• Rarely 3% saline will be needed
• Chronic tx
– Mild hyponatremia
• Water restriction to approx 1000 ml / day
• Demeclocycline 300 mg PO bid if water restriction not
working (contraindicated in liver disease)
SIADH
• Chronic treatment (cont)
– Vasopressin receptor antagonists
• Conivaptan (Vaprisol) IV prep
– 20 mg infusion over 30 min, then continuous
infusion of 20 mg/24 hrs
– Maximum dose 40 mg/24 hrs
– Maximum duration is 4 days
Hyponatremia
• How fast do we correct it?
Hyponatremia
• Treatment principles
– Not too fast (pontine myelinolysis)
• Symptomatic
– Initial 1 - 2 mEq / L / hr x two hours, then
– 0.5 mEq / L / hr
• Asymptomatic
– 0.5 mEq / L / hr
– Max in 24 hours: 10 meq total rise
– Max in 48 hours: 18 meq total rise
Hypernatremia
• Sodium: Normal 135 – 145 mEq / l
• Clinical manifestations
– Tremors
– Irritability
– Ataxia
– Spasticity
– Mental confusion
– Seizures
– Coma
– Death
Hypernatremia
• Cause:
– Net sodium gain
– Net water loss
Hypernatremia
• Volume expansion (net sodium gain)
– Cause
• Hypertonic saline / NaHCO3 administration
• Primary hyperaldosteronism
• Cushing’s syndrome
Tx: Diuretics
D5W to replace fluid loss after diuretics
Hypernatremia
• Water depletion
– Hypotonic fluid losses
Condition Urine vol Urine
osm
GI /
Insensible
loss
Low
High
Renal
High
loss
Diabetes High
Insipidus
High
Low
Hypovolemic hypernatremia
• Treatment
– Calculate free water deficit
• TBW (liters) = 0.6 x current total body weight (kg)
• Desired TBW (liters) =
Measured Na (mEq/l) x current TBW / Normal Na
• Body water deficit (liters) =
Desired TBW – current TBW
Hypovolemic hypernatremia
• If hemodynamic compromise, then replace
initially with NS
• Otherwise use ½ NS or D5W
– Aim to decrease Na by 0.5 mEq / liter / hr
– Correct one half of the water deficit in 24 hrs
– Correct other half over next 24-48 hours
Hypovolemic hypernatremia
• Diabetes insipidus
Sxs: Polyuria / Polydipsia / Low urine osm
– Central
• Tumor / Granuloma / Trauma / Surgery
– Nephrogenic
• Severe hypokalemia / hypercalcemia / CKD / Drugs
(lithium / demeclocycline / amphotericin)
Hypovolemic hypernatremia
• DI
– Differentiation of central and nephrogenic
• Trial of water deprivation
• Failure to concentrate urine confirms DI
• Subsequently given arginine vasopressin
– Central DI (urine concentration increases)
– Nephrogenic DI (no increase)
Hypovolemic hypernatremia
• DI
– Treatment
• Central
– Vasopressin 5-10 mcg intranasally per day / bid
• Nephrogenic
– Correction of underlying cause if possible
– Thiazide diuretic / salt restriction can help
Hypokalemia
• Normal K level: 3.5 – 5.0 MEq/L
• Clinical manifestations
– Fatigue
– Cramps
– Constipation
– Weakness / Paralysis
– Parasthesias
– Arrhythmias
Hypokalemia
• EKG abnormalites
– Flattened T waves
– ST depressions
– Prominent U waves
EKG Changes in Hypokalemia
Hypokalemia
• Causes
– GI losses
– Renal losses
– Acid-base shifts
Hypokalemia Treatment
• Oral therapy
– Mild hypokalemia
– Ability to tolerate oral replacement
– Increase dietary intake
• Potatoes / Bananas
– KCl preparations
• Can be used in range 8 – 20 mEq/L
• Monitor K level and adjust dose as needed
• Correct cause
Hypokalemia Treatment
• IV repletion
– Severe hypokalemia
– Inability to tolerate oral repletion
Max Concentration: 60 mEq / liter
Rate: 10 mEq / hr
Monitor response and decrease concentration or
rate as appropriate.
Hyperkalemia
• Potassium Normal 3.5 – 5.0
– Elevated potassium level should be evaluated as
to the following:
• What is the cause?
• Is the cause an acute or chronic issue?
• Are there accompanying EKG changes?
Hyperkalemia
• Symptoms
– Usually asymptomatic
– Muscle weakness / paralysis
– EKG abnormalities
•
•
•
•
•
Peaked T waves
ST depression
1st degree AVB
QRS widening
“Sine wave sign”
Hyperkalemia
• EKG changes
Hyperkalemia
• Think about the cause
• 1. Too much total potassium
– Renal disease
– Intake increased (rare outside of renal disease)
• 2. Shift of potassium from intracellular space
to extracellular space
– DKA
Hyperkalemia
• Does the potassium level make sense in
the patient?
Pseudohyperkalemia
Hyperkalemia
• When do we treat
– Patient assessment
• Cause
• Chronicity
– Degree of potassium elevation
• <6.0 Does not need acute invasive tx
• >6.0- 6.5 Kayexalate +/- other modalities
• >6.5 Consider more acute modalities
Hyperkalemia
• Treatment options
– Calcium gluconate
– Regular insulin
– Albuterol nebulizer treatment
– NaHCO3
– Kayexalate
– Dialysis
Hyperkalemia
• Calcium gluconate
– IV formulation is 1000 mg / 10 ml (10% soln)
– Dose:
– Action: Stabilization of cardiac cells. Does not
lower potassium. Used for hyperkalemia with
EKG changes.
– If EKG changes do not immediately resolve, dose
can be repeated in 5 minutes.
Hyperkalemia
• Calcium gluconate
– Precautions
• Do not infuse with bicarbonate (precipitation of calcium
carbonate)
• Do not use routinely with digitalis as hypercalcemia can
augment digitalis toxicity. Limit use to patients with
widened QRS.
Hyperkalemia
• Beta agonist
– Albuterol nebulizer treatment
• 2-4 ml of 0.5% soln (10-20 mg dose)
• Note a usual nebulizer tx for RAD is 2.5 mg
• Peak effect in 90 minutes
Hyperkalemia
• Insulin
– Regular insulin 10 units IV plus one D50 Amp over
5 minutes. This will give patient 25 grams of
glucose.
– Follow this with a D 5 containing IV maintenance
fluid for several hours.
– Effect within 15 minutes. Peak effect 60 min.
Duration 3-4 hours.
Hyperkalemia
• NaHCO3
– 1 Amp (44.6 meq) IV over 5 minutes.
– Onset: 30 minutes
– Duration: 60-120 minutes
Hyperkalemia
• Kayexalate
(Na – K exchange resin)
– PO dosing: 15 -30 gram
• Can be used as a dry powder
• Can be mixed with 60-120 ml of a 20% sorbitol soln to
avoid constipation
– PR dosing: 50 grams
• Mix with 50 ml of 70% sorbitol and 100 ml tap H20
• Retain in rectum x 30 minutes minimum but ideally 2+
hours
Hypocalcemia
• Normal Calcium: 8.9 – 10.3 mg/dl
• Calcium
– 40% bound to albumin
– 15% bound to other serum anions
– 45% is ionized in serum
Hypocalcemia
• Correct for low albumin
• 0.8 mg / dl drop in Calcium for every 1 g / dl
drop in Albumin
• Corr Ca = Meas Ca + (0.8 * (4.5 – Meas Alb))
Hypocalcemia
• Clinical signs of low calcium:
– Tetany / Carpopedal spasm
– Trousseau’s sign
– Chvostek’s sign
– Lethargy / confusion
– Seizures
– Heart failure
Hypocalcemia
• Treatment of symptomatic cases
– Calcium gluconate (10% soln) which contains 100
mg elem calcium / 10 ml.
1. Give two ampules IV over 10 minutes
then
2. Add six ampules to 500 ml D5W and infuse
at 1 mg / kg / hr
Hypocalcemia
• Asymptomatic
– Calcium orally (1000 mg / day)
– Vit D orally
• Calcitriol 0.25 – 0.5 mcg / day
Hypocalcemia
• Magnesium can be effective as well
– Magnesium sulfate 2 gram IV bolus followed by 1
gram / hr gtt
Hypercalcemia
• Calcium range: 8.9 – 10.3 mg / dl
Hypercalcemia
• Symptoms
– Anorexia
– N/V
– Constipation
– Polyuria
– Nephrolithiasis
– Weakness
– Confusion
– Coma
– EKG: Shortened QT interval
Hypercalcemia
• Causes
–
–
–
–
–
–
–
–
–
–
Primary hyperparathyroidism
Malignancy
Sarcoidosis
Vitamin D toxicity
Hyperthyroidism
Thiazide diuretics
Milk-alkali syndrome
Renal failure
Familial hypocalciuric hypercalcemia
Immobilization
Hypercalcemia
• Treatment
– Increase urinary excretion
– Diminish bone resorption
– Diminish GI absorption
– Chelation of ionized Ca (EDTA)
– Dialysis
Hypercalcemia
• Treatment:– Increase urinary excretion
• NS @ 200 – 300 ml / hr to achieve UO = 100
ml /hr
• Lasix (if fluid overloaded state exists)
Hypercalcemia
• Treatment
– Decrease bone resorption
• Calcitonin 4 units SQ or IM q 12 hours
– This approach works rapidly (4 hrs) and lowers
Ca by 1-2 mg / dl
– Tachyphylaxsis develops after 48 hours
– Note that nasal dosing does not lower calcium
Hypercalcemia
• Treatment (Decrease bone resorption)
– Bisphosphonates
• Zoledronic Acid
• Pamidronate
Hypercalcemia
• Treatment:– Decreased oral absorption (Need in
sarcoid)
• Oral phosphate administration
• Prednisone
Hypercalcemia
• Treatment
– Dialysis
• Consider in severe severe severe case
• Ca 18-20 mg / dl
Hypomagnesemia
• Normal: Magnesium 1.7 – 2.4 mg / dl
Hypomagnesemia
• Think about hypomagnesemia in the following
situations:
– Alcoholism
– Hypokalemia
– Hypocalcemia
– Chronic diarrhea
– Ventricular arrhythmias
Hypomagnesemia
• Differentiate urinary from GI losses
• FeMg =
(UrMg * PCr) *100
(0.7*PMg*UCr)
<2% = GI loss
>2% = Renal loss
Hypomagnesemia
• Treatment
– Severe (<1.0)
• IV Magnesium sulfate
2 grams IV over 1 hr
– Mild – moderate
• PO Magnesium
– Magnesium chloride (Slo-Mag) 2 tabs PO q day
– Magnesium oxide (Mag-Ox 400) 2 tabs PO q day
Hypermagnesemia
• Magnesium: Normal range 1.7-2.4
• Seen in renal failure with concomitant tx with
magnesium containing antacids / laxatives
• Seen in preeclampsia treated with Magnesium
sulfate
• Notable if Mg >4.0
Hypermagnesemia
• Treatment
– Stop the exogenous magnesium
– HD may be needed in the setting of renal failure
– Calcium gluconate (10%) 1-2 ampules IV can be
given as a bridge to setting up dialysis
Hypophosphatemia
• Phosphorus: Normal 2.6-4.5 mg / dl
• Causes
– Hyperglycemic states
– Alcoholism
– Respiratory alkalosis
– GI abns
– Alum / Mg containing antacids
– Hyperparathyroidism
– Renal wasting
Hypophosphatemia
• Treatment
– Treat underlying cause
– Replete if severely low
• Below 1 mg / dl in DKA
– IV KPhos
– PO Neutraphos
Hyperphosphatemia
• Phosphorus: Normal 2.6 – 4.5 mg /dl
• Causes:
– Renal failure
– Hypoparathyroidism
– Rhabdomyolysis
– Tumor lysis syndrome
– Acidotic states
– Exogenous admin of phosphorus
Hyperphosphatemia
• Treatment:
– Dietary restriction 0.6 – 0.9 grams / day
– Oral phosphate binders
• Calcium acetate 2 tabs PO q AC
• May need to add aluminum containing product
(aluminum hydroxide)
– Dialysis