Each electrolyte has a special function in the body,
although if one electrolyte is out of balance, the concentrations
and actions of other electrolytes are often
affected. The serum concentration of sodium, potassium,
and chloride can be measured in a simple blood
test.
Sodium, chloride, potassium, and calcium concentrations
can also be determined from a urine sample.
A urine test helps show how well the kidneys are
functioning. Electrolyte imbalances are most common
among the seriously ill and the elderly. Kidney (renal)
failure is the most common cause of electrolyte
imbalances.
SODIUM. Sodium affects how much urine the kidney
produces and is involved in the transmission of
nerve impulses and muscle contraction. Too high a
concentration of sodium in the blood causes a condition
called hypernatremia. Causes of hypernatremia
include excessive water loss (e.g., severe diarrhea),
restricted water intake, untreated diabetes (causes
water loss), kidney disease, hormonal imbalances,
and excessive salt (NaCL) intake. Symptoms include
signs of dehydration such as extreme thirst, dark
urine, sunken eyes, fatigue, irregular heart beat,
muscle twitching, seizures, and coma.
Too low a concentration of sodium in the blood
causes hyponatremia. This is one of the most common
electrolyte imbalances, and occurs in about 1% of
hospitalized individuals. It can result from vomiting,
diarrhea, severe burns, taking certain drugs that cause
the kidneys to selectively excrete sodium, inadequate
salt intake, water intoxication (a problem among the
elderly with dementia), hormonal imbalances, kidney
failure, and liver damage. Symptoms include nausea,
vomiting, headache, tissue swelling (edema), confusion,
mental disorientation, hallucinations, muscle
trembling, seizures, and coma.
POTASSIUM. Potassium ions play a major role in
regulating fluid balance in cells, the transmission of
nerve impulses, and in muscle contractions. Too high
a concentration of potassium causes a condition called
hyperkalemia that is potentially life threatening. The
most common cause is kidney failure. It can also result
from severe burns or injury (excess potassium released
from injured cells), inadequate adrenal hormones
(Addison’s disease), the use of certain medications,
and excessive use of potassiumsupplements. Sometimes
hyperkalemia occurs in conjunctions with hypernatremia.
Symptoms include nausea, diarrhea, weakness,
muscle pain, and irregular heart beat, coma and death.
Abnormally low concentrations of potassium
cause hypokalemia. Hypokalemia can result from
excess adrenal hormones (Cushing’s disease), kidney
disease, long-term use of certain diuretic drugs, laxative
abuse, bulimia, and kidney failure. Symptoms
include increased production of urine, muscle pain,
paralysis, irregular heart beat, and low blood pressure.
CALCIUM. Calcium is needed to build and maintain
bones. It also plays a role in nerve impulse transmission
and muscle contraction. Excess calcium
results in a condition called hypercalcemia. Hypercalcemia
can be caused by too much parathyroid hormone
(PTH), certain cancers, some genetic disorders,
and excessive use of antacids containing calcium in
rare cases. Symptoms include bone and muscle pain,
mental changes such as depression and confusion,
increased urine production, fatigue, nausea, and
vomiting.
Abnormally low concentrations of calcium cause
hypocalcemia. Hypocalcemia can be caused by too
little parathyroid hormone, kidney failure, and vitamin
D deficiency. Vitamin D is necessary for the body
to absorb calcium. Symptoms include muscle twitches
and spasms, convulsions, mental changes such as
depression and irritability, dry skin, and brittle nails.
MAGNESIUM. Magnesium is involved in protein
synthesis and cellular metabolism. Abnormally high
concentrations of magnesium, or hypermagnesemia,
may occur with severe (end-stage) renal failure or by
overdose of magnesium-containing intravenous fluids.
Hypermagnesemia is rare. Symptoms include
exhaustion, low blood pressure, depressed heart and
breathing rate, and slow reflexes.
Abnormally low concentrations of magnesium, or
hypomagnesemia, are most common among people
with alcoholism and those who are severely malnourished.
Other causes include digestive disorders that
interfere with the absorption of magnesium from the
intestines. Symptoms of hypomagnesemia include
vomiting, weight lose, leg cramps, muscle spasms,
seizures, and irregular heartbeat.
CHLORIDE. Chloride is involved in regulating
blood pressure. High concentrations of chloride,
called hyperchloremia, can be caused by kidney failure,
kidney dialysis, and an overproduction of parathyroid
hormone. Symptoms include weakness,
headache, nausea, and vomiting. In people with diabetes,
hyperchloremia makes it difficult to control
blood glucose levels.
Hypochloremia often occurs along with hyponatremia
or hypokalemia and is caused by excessive fluid
loss (e.g., diarrhea). Serious deficiencies of chloride
cause the blood to become less acidic, resulting in a
condition called metabolic alkalosis. Symptoms of
severe hypochloremia include confusion, paralysis,
and difficulty breathing.
PHOSPHATE. Phosphate helps control the acidity
level (pH) of the blood. Phosphate also causes calcium
to be deposited in bones. High blood levels of phosphate,
or hyperphosphatemia, often result in too low
levels of calcium, or hypocalcemia. Hyperphosphatemia
is usually caused by kidney failure. It can also
result from kidney dialysis, parathyroid gland dysfunction,
and several inherited diseases. Mild hyperphosphatemia
usually produces no symptoms. Severe
imbalance can cause tingling in the fingers, muscle
cramps, and convulsions.
Hypophosphatemia, or abnormally low concentrations
of phosphate in the blood, often occurs along
with hypomagnesemia and hypokalemia. It can also
be caused by kidney disease, kidney dialysis, vitamin
Ddeficiency, and hormonal imbalances. Up to 30% of
individuals admitted to hospital intensive care units
have hypophosphatemia.
