Editing Phosphate (section)

== '''Hypophosphataemia''' ==

* Commonly seen during recovery from critical illness
* '''Causes''' (most commonly refeeding syndrome in surgical patients)
**

{| class="wikitable"
|'''Internal redistribution'''
|-
|Increased insulin secretion, particularly during refeeding
|-
|Acute respiratory alkalosis
|-
|Hungry bone syndrome
|-
|'''Decreased intestinal absorption'''
|-
|Inadequate intake
|-
|Inhibition of phosphate absorption (eg, antacids, phosphate binders, niacin)
|-
|Steatorrhea and chronic diarrhoea
|-
|Vitamin D deficiency or resistance
|-
|'''Increased urinary excretion'''
|-
|Primary and secondary hyperparathyroidism
|-
|Vitamin D deficiency or resistance
|-
|Hereditary hypophosphatemic rickets
|-
|Oncogenic osteomalacia
|-
|Fanconi syndrome
|-
|Other - acetazolamide, tenofovir, IV iron, chemotherapeutic agents
|-
|'''Removal by kidney replacement therapies'''
|}

* Symptoms mostly occur below serum 0.32mmol/L
** Metabolic encephalopathy, impaired myocardial contractility, respiratory failure to diaphragmatic weakness, proximal myopathy, dysphagia, ileus
* '''Asymptomatic patients''' with '''serum phosphate <0.64mmol/L, give oral phosphate'''
* '''Symptomatic patients'''
** '''Serum phosphate 0.32 to 0.63mmol/L: oral phosphate'''
** '''Serum phosphate <0.32: IV phosphate''', switching back to oral when serum levels >0.48
* Stop repletion when serum level >0.64 unless there is an indication for chronic therapy
* Oral repletion should be given as a combined preparation of sodium and potassium phosphate; sodium phosphate is preferred for IV therapy
* Oral dosing: 30-80mmol per day in divided doses
** Serum >0.48: 1mmol/kg of elemental phosphorus (min 40, max 80) can be given in 3-4 divided doses over 24 hours
** Serum <0.48: 1.3mmol/kg of elemental phosphorus (max 100mmol) in 3-4 divided doses over 24 hours
** If reduced GFR, give half the dose
** Recheck 2-12 hours post the last of the divided doses
* IV dosing
** Be very careful - can precipitate with calcium and produce adverse effects including hypocalcaemia, kidney failure, arrhythmias
** Serum >0.4: 0.08-0.24mmol/kg over 6 hours (max total dose 30mmol)
** Serum <0.4: 0.25-0.5mmol/kg over 8-12 hours (max total dose 80mmol)
* If eGFR < 30, give half the usual dose


[[Category:Nutrition]]
[[Category:Intern education]]