Hypophosphatemia is an electrolyte disturbance in which there is an
Hypophosphatemia is an electrolyte disturbance in which there is an

abnormally low level of phosphate in the blood. The condition has many causes,
abnormally low level of phosphate in the blood. The condition has many causes,

but is most commonly seen when malnourished patients are given large
but is most commonly seen when malnourished patients are given large

amounts of carbohydrates, which creates a high phosphorus demand by cells,
amounts of carbohydrates, which creates a high phosphorus demand by cells,

removing phosphate from the blood. Because a decrease in phosphate in the
removing phosphate from the blood. Because a decrease in phosphate in the

blood is sometimes associated with an increase in phosphate in the urine, the
blood is sometimes associated with an increase in phosphate in the urine, the

terms hypophosphatemia and "phosphaturia" are occasionally used
terms hypophosphatemia and "phosphaturia" are occasionally used

interchangeably; however, this is improper since there exist many causes
interchangeably; however, this is improper since there exist many causes

of hypophosphatemia besides overexcretion and phosphaturia, and in
of hypophosphatemia besides overexcretion and phosphaturia, and in

fact the most common causes of hypophosphatemia are not associated with
fact the most common causes of hypophosphatemia are not associated with

phosphaturia. Common causes of hypophosphatemia
phosphaturia. Common causes of hypophosphatemia

Refeeding syndrome This causes a demand for phosphate in cells due to the action
Refeeding syndrome This causes a demand for phosphate in cells due to the action

of Hexokinase, an enzyme that attaches phosphate to glucose to begin metabolism
of Hexokinase, an enzyme that attaches phosphate to glucose to begin metabolism

of glucose. Also, production of ATP when cells are fed and recharge their energy
of glucose. Also, production of ATP when cells are fed and recharge their energy

supplies, requires phosphate. Respiratory alkalosis Any alkalemic
supplies, requires phosphate. Respiratory alkalosis Any alkalemic

condition moves phosphate out of the blood into cells. This includes most
condition moves phosphate out of the blood into cells. This includes most

common respiratory alkalemia, which in turn is caused by any hyperventilation.
common respiratory alkalemia, which in turn is caused by any hyperventilation.

This phenomenon is seen because in respiratory alkalosis carbon dioxide
This phenomenon is seen because in respiratory alkalosis carbon dioxide

decreases in the extracellular space, causing intracellular CO2 to freely
decreases in the extracellular space, causing intracellular CO2 to freely

diffuse out of the cell. This drop in intracellular CO2 causes a rise in
diffuse out of the cell. This drop in intracellular CO2 causes a rise in

cellular pH which has a stimulating effect on glycolysis. Since the process
cellular pH which has a stimulating effect on glycolysis. Since the process

of glycolysis requires phosphate, the result is a massive uptake of phosphate
of glycolysis requires phosphate, the result is a massive uptake of phosphate

into metabolically active tissue from the serum. It is interesting to note,
into metabolically active tissue from the serum. It is interesting to note,

however, that this effect is not seen in metabolic alkalosis, for in such cases
however, that this effect is not seen in metabolic alkalosis, for in such cases

the cause of the alkalosis is increased bicarbonate rather than decreased CO2.
the cause of the alkalosis is increased bicarbonate rather than decreased CO2.

Bicarbonate, unlike CO2, has poor diffusion across the cellular membrane
Bicarbonate, unlike CO2, has poor diffusion across the cellular membrane

and therefore there is little change in intracellular pH.
and therefore there is little change in intracellular pH.

Alcohol abuse Alcohol impairs phosphate absorption. Alcoholics are usually also
Alcohol abuse Alcohol impairs phosphate absorption. Alcoholics are usually also

malnourished with regard to minerals. In addition, alcohol treatment is
malnourished with regard to minerals. In addition, alcohol treatment is

associated with refeeding, and the stress of alcohol withdrawal may create
associated with refeeding, and the stress of alcohol withdrawal may create

respiratory alkalosis, which exacerbates hypophosphatemia.
respiratory alkalosis, which exacerbates hypophosphatemia.

Malabsorption This includes GI damage, and also failure to absorb phosphate due
Malabsorption This includes GI damage, and also failure to absorb phosphate due

to lack of vitamin D, or chronic use of phosphate binders such as sucralfate,
to lack of vitamin D, or chronic use of phosphate binders such as sucralfate,

aluminum-containing antacids, and calcium-containing antacids.
aluminum-containing antacids, and calcium-containing antacids.

Primary hypophosphatemia is the most common cause of nonnutritional rickets.
Primary hypophosphatemia is the most common cause of nonnutritional rickets.

Laboratory findings include low-normal serum calcium, moderately low serum
Laboratory findings include low-normal serum calcium, moderately low serum

phosphate, elevated serum alkaline phosphatase, and low serum 1,25
phosphate, elevated serum alkaline phosphatase, and low serum 1,25

dihydroxy-vitamin D levels, hyperphosphaturia, and no evidence of
dihydroxy-vitamin D levels, hyperphosphaturia, and no evidence of

hyperparathyroidism. Other rarer causes include
hyperparathyroidism. Other rarer causes include

Certain blood cancers such as lymphoma or leukemia
Certain blood cancers such as lymphoma or leukemia

Hereditary causes Liver failure
Hereditary causes Liver failure

Tumor-induced osteomalacia Pathophysiology
Tumor-induced osteomalacia Pathophysiology

Hypophosphatemia is caused by the following three mechanisms:
Hypophosphatemia is caused by the following three mechanisms:

Inadequate intake Increased excretion
Inadequate intake Increased excretion

Shift from extracellular to intracellular space and acute
Shift from extracellular to intracellular space and acute

respiratory alkalosis) Major signs and symptoms
respiratory alkalosis) Major signs and symptoms

Muscle dysfunction and weakness. This occurs in major muscles, but also may
Muscle dysfunction and weakness. This occurs in major muscles, but also may

manifest as: diplopia, low cardiac output, dysphagia, and respiratory
manifest as: diplopia, low cardiac output, dysphagia, and respiratory

depression due to respiratory muscle weakness.
depression due to respiratory muscle weakness.

Mental status changes. This may range from irritability to gross confusion,
Mental status changes. This may range from irritability to gross confusion,

delirium, and coma. White cell dysfunction, causing
delirium, and coma. White cell dysfunction, causing

worsening of infections. Instability of cell membranes due to low
worsening of infections. Instability of cell membranes due to low

ATP levels: this may cause rhabdomyolysis with increased CPK, and
ATP levels: this may cause rhabdomyolysis with increased CPK, and

also hemolytic anemia. Increased affinity for oxygen in the
also hemolytic anemia. Increased affinity for oxygen in the

blood caused by decreased production of 2,3BPG.
blood caused by decreased production of 2,3BPG.

Large pulp chambers in the teeth. Treatment
Large pulp chambers in the teeth. Treatment

Standard intravenous preparations of potassium phosphate are available and
Standard intravenous preparations of potassium phosphate are available and

are routinely used in malnourished patients and alcoholics. Oral
are routinely used in malnourished patients and alcoholics. Oral

supplementation also is useful where no intravenous treatment is available.
supplementation also is useful where no intravenous treatment is available.

Historically one of the first demonstrations of this was in
Historically one of the first demonstrations of this was in

concentration camp victims who died soon after being re-fed: it was observed that
concentration camp victims who died soon after being re-fed: it was observed that

those given milk had a higher survival rate than those who did not get milk.
those given milk had a higher survival rate than those who did not get milk.

monitoring parameters during correction with IV phosphate
monitoring parameters during correction with IV phosphate

Phosphorus levels should be monitored after 2 to 4 hours after each dose, also
Phosphorus levels should be monitored after 2 to 4 hours after each dose, also

monitor serum potassium, calcium and magnesium. Cardiac monitoring is also
monitor serum potassium, calcium and magnesium. Cardiac monitoring is also

advised. See also
advised. See also

Hyperphosphatemia Hypophosphatasia
Hyperphosphatemia Hypophosphatasia

X-linked hypophosphatemia External links
X-linked hypophosphatemia External links

eMedicine review Tutorial - complications
eMedicine review Tutorial - complications

Refeeding Syndrome References
Refeeding Syndrome References