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| ==Overview== | | ==[[Hypophosphatemia overview|Overview]]== |
| '''Hypophosphatemia''' is an [[electrolyte disturbance]] in which there is an abnormally low level of [[phosphate]] in the [[blood]]. The condition has many causes, but is most commonly seen when malnourished patients (especially [[chronic alcoholics]]) are given large amounts of carbohydrates, which create a high phosphorus demand by cells, removing phosphate from the blood (''[[refeeding syndrome]]'').
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| Because a ''decrease'' in phosphate in the blood is sometimes associated with an ''increase'' in phosphate in the [[urine]], the terms hypophosphatemia and "[[phosphaturia]]" are occasionally used interchangeably; however, this is improper since there exist many causes of hypophosphatemia besides overexcretion and [[phosphaturia]], and in fact the most common causes of hypophosphatemia are not associated with [[phosphaturia]].
| | ==[[Hypophosphatemia historical perspective|Historical Perspective]]== |
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| ==Pathophysiology== | | ==[[Hypophosphatemia classification|Classification]]== |
| Hypophosphatemia is caused by the following three mechanisms:
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| * Inadequate intake (often unmasked in refeeding after long-term low phosphate intake)
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| * Increased excretion (e.g. in hyperparathyroidism)
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| * Shift from extracellular to intracellular space (seen in treatment of [[diabetic ketoacidosis]], refeeding, short-term increases in cellular demand (e.g., hungry bones syndrome) and acute [[respiratory alkalosis]])
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| ==Causes== | | ==[[Hypophosphatemia pathophysiology|Pathophysiology]]== |
| ===Common Causes of hypophosphatemia===
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| *[[Refeeding syndrome]] This causes a demand for phosphate in cells due to the action of [[phosphofructokinase]], an enzyme which attaches phosphate to glucose to begin metabolism of this. Also, production of [[ATP]] when cells are fed and recharge their energy supplies, requires phosphate.
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| * [[Respiratory alkalosis]] Any alkalemic condition moves phosphate out of the blood into cells. This includes most common respiratory alkalemia (a higher than normal blood pH from low carbon dioxide levels in the blood), which in turn is caused by any hyperventilation (such as sepsis, fever, pain, anxiety, drug withdrawal).
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| * [[Alcohol abuse]] Alcohol impairs phosphate absorption, and alcoholics are also after malnurished with regard to minerals. In addition, alcohol treatment is associated with refeeding, and the stress of alcohol withdrawal may create respiratory alkalosis, which exacerbates hypophosphatemia (see above).
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| * [[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]], aluminum-containing antacids, and (more rarely) calcium-containing antacids.
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| * Hyperexcretion of phosphate in the urine (phosphaturia). This includes excess excretion from renal dysfunction, and also the action of many classes of [[diuretic]]s. Additionally, both primary and secondary [[hyperparathyroidism]] causes hyperexcretion of phosphate in the urine.
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| Other rarer causes include
| | ==[[Hypophosphatemia causes|Causes]]== |
| * Certain blood cancers such as [[lymphoma]] or [[leukemia]]
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| * [[Hereditary]] causes
| | ==[[Hypophosphatemia differential diagnosis|Differentiating Hypophosphatemia from other Diseases]]== |
| * [[Hepatic failure]]
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| | ==[[Hypophosphatemia epidemiology and demographics|Epidemiology and Demographics]]== |
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| | ==[[Hypophosphatemia risk factors|Risk Factors]]== |
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| | ==[[Hypophosphatemia screening|Screening]]== |
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| | ==[[Hypophosphatemia natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
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| ==Diagnosis== | | ==Diagnosis== |
| ==Major signs and symptoms==
| | [[Hypophosphatemia staging|Staging]] | [[Hypophosphatemia history and symptoms|History and Symptoms]] | [[Hypophosphatemia physical examination|Physical Examination]] | [[Hypophosphatemia laboratory findings|Laboratory Findings]] | [[Hypophosphatemia chest x ray|Chest X Ray]] | [[Hypophosphatemia CT|CT]] | [[Hypophosphatemia MRI|MRI]] | [[Hypophosphatemia other imaging findings|Other Imaging Findings]] | [[Hypophosphatemia other diagnostic studies|Other Diagnostic Studies]] |
| * [[Muscle weakness]]. This occurs in major muscles, but also may manifest as [[diplopia]], [[low cardiac output]] (including [[myonecrosis]] and [[cardiomyopathy]], [[dysphagia]], and respiratory depression due to respiratory muscle weakness.
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| * [[Mental status changes]]. This may range from irritability to gross [[confusion]], [[delirium]], and [[coma]].
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| * White cell dysfunction, causing worsening of infections
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| * Instability of cell membrates due to low ATP levels: this may cause [[rhabdomyolysis]] with increased CPK, and also [[hemolytic anemia]].
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| ==Treatment== | | ==Treatment== |
| Standard intravenous preparations of potassium phosphate are available and are routinely used in malnurished patients and alcoholics. Oral supplementation also is useful where no intravenous treatment is available. Historically one of the first demonstrations of this was in concentration camp victims who died soon after being re-fed: it was observed that those given milk (high in phosphate) had a higher survival rate than those who did not get milk.
| | [[Hypophosphatemia medical therapy|Medical Therapy]] | [[Hypophosphatemia surgery|Surgery]] | [[Hypophosphatemia primary prevention|Primary Prevention]] | [[Hypophosphatemia secondary prevention|Secondary Prevention]] | [[Hypophosphatemia cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Hypophosphatemia future or investigational therapies|Future or Investigational Therapies]] |
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| | ==Case Studies== |
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| | [[Hypophosphatemia case study one|Case #1]] |
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| ==See also== | | ==See also== |