998
UNIT 4
Maintenance of the Body
26
Table 26.1
Causes and Consequences of Electrolyte Imbalances
ION
ABNORMALITY
(SERUM VALUE)
POSSIBLE CAUSES
CONSEQUENCES
Sodium
Hypernatremia (Na
1
excess:
.
145 mEq/L)
Dehydration; uncommon in healthy
individuals; may occur in infants or the
confused aged (individuals unable to
indicate thirst) or may result from excessive
intravenous NaCl administration
Thirst. CNS dehydration leads to confusion
and lethargy progressing to coma; increased
neuromuscular irritability evidenced by
twitching and convulsions.
 
Hyponatremia (Na
1
deficit:
,
135 mEq/L)
Solute loss, water retention, or both (e.g.,
excessive Na
1
loss through vomiting,
diarrhea, burned skin, tubal drainage of
stomach, or excessive use of diuretics);
deficiency of aldosterone (Addison’s disease);
renal disease; excess ADH release; excess H
2
O
ingestion
Most common signs are those of neurologic
dysfunction due to brain swelling. If sodium
amounts are actually normal but water is
excessive, the symptoms are the same as
those of water excess: mental confusion;
giddiness; coma if development occurs
slowly; muscular twitching, irritability, and
convulsions if the condition develops rapidly.
In hyponatremia accompanied by water loss,
the main signs are decreased blood volume
and blood pressure (circulatory shock).
Potassium
Hyperkalemia (K
1
excess:
.
5.5 mEq/L)
Renal failure; deficit of aldosterone; rapid
intravenous infusion of KCl; burns or severe
tissue injuries that cause K
1
to leave cells
Nausea, vomiting, diarrhea; bradycardia;
cardiac arrhythmias, depression, and arrest;
skeletal muscle weakness; flaccid paralysis.
 
Hypokalemia (K
1
deficit:
,
3.5 mEq/L)
Gastrointestinal tract disturbances (vomiting,
diarrhea), gastrointestinal suction; Cushing’s
syndrome; inadequate dietary intake
(starvation); hyperaldosteronism; diuretic
therapy
Cardiac arrhythmias, flattened T wave;
muscular weakness; metabolic alkalosis;
mental confusion; nausea; vomiting.
Phosphate
Hyperphosphatemia
(HPO
4
2
2
excess:
.
2.9
mEq/L)
Decreased urinary loss due to renal failure;
hypoparathyroidism; major tissue trauma;
increased intestinal absorption
Clinical symptoms arise because of reciprocal
changes in Ca
2
1
levels rather than directly
from changes in plasma phosphate
concentrations.
 
Hypophosphatemia
(HPO
4
2
2
deficit:
,
1.6
mEq/L)
Decreased intestinal absorption; increased
urinary output; hyperparathyroidism
 
Chloride
Hyperchloremia (Cl
2
excess:
.
105 mEq/L)
Dehydration; increased retention or intake;
metabolic acidosis; hyperparathyroidism
No direct clinical symptoms; symptoms
generally associated with the underlying
cause, which is often related to pH
abnormalities.
 
Hypochloremia (Cl
2
deficit:
,
95 mEq/L)
Metabolic alkalosis (e.g., due to vomiting or
excessive ingestion of alkaline substances);
aldosterone deficiency
 
Calcium
Hypercalcemia (Ca
2
1
excess:
.
5.2 mEq/L or
10.5 mg%)*
Hyperparathyroidism; excessive vitamin D;
prolonged immobilization; renal disease
(decreased excretion); malignancy
Decreased neuromuscular excitability leading
to cardiac arrhythmias and arrest, skeletal
muscle weakness, confusion, stupor, and
coma; kidney stones; nausea and vomiting.
 
Hypocalcemia (Ca
2
1
deficit:
,
4.5 mEq/L or
9 mg%)*
Burns (calcium trapped in damaged tissues);
hypoparathyroidism; vitamin D deficiency;
renal tubular disease; renal failure;
hyperphosphatemia; diarrhea; alkalosis
Increased neuromuscular excitability leading
to tingling fingers, tremors, skeletal muscle
cramps, tetany, convulsions; depressed
excitability of the heart; osteomalacia;
fractures.
Magnesium
Hypermagnesemia
(Mg
2
1
excess:
.
2.2
mEq/L)
Rare; occurs in renal failure when Mg
2
1
is
not excreted normally; excessive ingestion of
Mg
2
1
-containing antacids
Lethargy; impaired CNS functioning, coma,
respiratory depression; cardiac arrest.
 
Hypomagnesemia
(Mg
2
1
deficit:
,
1.4
mEq/L)
Alcoholism; chronic diarrhea, severe
malnutrition; diuretic therapy
Tremors, increased neuromuscular excitability,
tetany, convulsions.
*1 mg%
5
1 mg/100 ml
previous page 1032 Human Anatomy and Physiology (9th ed ) 2012 read online next page 1034 Human Anatomy and Physiology (9th ed ) 2012 read online Home Toggle text on/off