How to interpret laboratory data:electrolytes
decrease
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Increase
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Normal range
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SI
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conventional
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Hyponatremia
1-(dilutional
hyponatremia)
excess
accumulation of body water due to:
CHF,
cirrhosis,
severe
burns,
chronic
renal failure, nephrotic syndrome.
2-Sodium
depletion
Due to:
SIADH,
cystic
fibrosis, mineralocorticoid deficiency,
Na
free fluid replacement
SIADH= (syndrome of inappropriate antidiuretic hormone)
SIADH may be
associated with disease states such as cancer or
the use of
medications including
chlorpropamide, thiazide diuretics, and carbamazepine.
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Hypernatremia
1-Increased
sodium intake.
2-Increased
fluid loss.
hypernatremia
usually occurs in individuals who are unable
to obtain
adequate fluid intake.
Fluid loss from
-
gastroenteritis
-
diabetes insipidus,
-
Cushing disease,
-
hyperaldosteronism
-
administration of hypertonic saline solution
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135-147 mmol/L
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135-147 mEq/L
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Sodium
(Na+)
is the most prevalent cation in the extracellular fluid.
Sodium
is important in: regulating serum osmolality,
fluid balance,
acid-base
balance.
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hypokalemia
severe diarrhea
and/or
vomiting,
respiratory
alkalosis, hyperaldosteronism, Cushing disease, alcoholism
Medications:
amphotericin B
thiazide,
loop,
osmotic
diuretics.
If a patient is
hypokalemic and potassium supplements have not helped to correct the low
potassium, check to see if the magnesium is also low.
Decreased potassium is difficult to correct while magnesium
remains low.
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Hyperkalemia
metabolic or
respiratory
acidosis,
renal failure,
Addison
disease, dehydration,
massive cell
damage
from burns,
injuries, and surgery.
Medications:
(ACE)
inhibitors, (ARBs),
potassium
supplements K-sparing diuretics
drospirenone
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3.5-5.2 mmol/L
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3.5-5.2 meq/L
high
potassium value may be reported
if the specimen was hemolyzed when the laboratory test was
performed
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Potassium
(K+) is the main
intracellular cation. Serum concentrations of potassium are not always an
accurate indicator of potassium levels because potassium
is an
intracellular ion. Potassium plays a key role in many bodily functions,
including:
regulation of
nerve excitability,
acid-base
balance, muscle function.
Cardiac
function and neuromuscular function can be significantly affected by either
an increase or decrease in potassium levels.
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Hypochloremia
prolonged
vomiting,
gastric
suctioning, metabolic alkalosis,
CHF,
SIADH,
Addison
disease,
medications
H2 blockers
proton pump inhibitors [PPIs]
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Hyperchloremia
metabolic
acidosis, respiratory alkalosis, dehydration,
diabetes
insipidus, eclampsia,
renal
disorders.
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95-106 mmol/L
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95-106 mEq/L
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Chloride
Cl is the
principal extracellular anion.
Chloride
primarily serves a
passive role in
the maintenance of fluid balance and acid-base balance.
Serum chloride
values are useful in identifying fluid or acid-base balance disorders.
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metabolic
acidosis.
diabetic
ketoacidosis, methanol toxicity,
salicylate
toxicity,
lactic acidosis,
renal failure.
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metabolic
alkalosis.
diuretic
therapy, primary aldosteronism, Bartter syndrome.
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22-30 mmol/L
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22-30 mEq/L
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Carbon Dioxide Content
The majority of
CO2 in the plasma is present as bicarbonate ions, and a small percentage is dissolved
CO2.
The CO2 content
is the sum of both bicarbonate
ions and dissolved
CO2. CO2 and bicarbonate are extremely important in
regulating
physiologic pH.
CO2 content is composed
mostly of bicarbonate (HCO3−) and is a base.
CO2 content is
regulated by the kidneys.
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Clinical Significance
Anion gap may
be elevated in conditions such as
renal failure,
lactic
acidosis,
ketoacidosis,
salicylate toxicity,
methanol toxicity ,
ethylene glycol toxicity.
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3-11 mmol/L
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3-11 mEq/L
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Anion Gap
The anion gap
is calculated using the following formula:
Anion gap = [Na+ - (Cl2 + HCO3
2)]
Anion gap is
reflective of unmeasured acids. An increase in anion gap
suggests an
increase in the number of negatively charged weak acids in theplasma. Anion
gap is useful in evaluating causes of metabolic acidosis.
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