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Hypophosphatemia
From WikEM
Contents
Background
- Phosphate required in function of all hematologic cells (RBCs, WBCs, platelets)
Clinical Features
- CNS
- Weakness
- Circumoral and fingertip paresthesias
- Decreased DTRs
- Decreased Mental Status
- Cardiac
- Impaired myocardial function
Differential Diagnosis
Causes of Hypophosphatemia
- Internal redistribution
- Refeeding of malnourished
- DKA
- Nonketotic hyperglycemia
- Receiving hyperalimentation
- Acute respiratory alkalosis
- Hungry bone syndrome
- Decreased intestinal absorption
- Inadequate intake
- Antacids containing aluminum or magnesium
- Steatorrhea and/or chronic diarrhea
- Increased urinary excretion
- Vitamin D deficiency or resistance
- Primary renal phosphate wasting (rare genetic disorders)
- Fanconi syndrome
- Osmotic diuresis (most often due to glucosuria)
- Proximally acting diuretics (e.g. acetazolamide and some thiazide diuretics)
- Acute volume expansion
- Intravenous iron administration
- Renal replacement therapy (dialysis)
Evaluation
- 2.5-2.8 Mild
- 1.0-2.5 Moderate
- <1.0 Severe
Management
- Mild-moderate
- KPhos /neutra phos PO
- Severe
- KPhos 2.5-5mg/kg IV over 6hr
Harbor UCLA Adult Treatment Guidelines
Serum phosphate 1mg/dl to 2mg/dl
- Able to take PO
- Minimize or eliminate all dextrose-containing IV solutions
- Aggressively treat acidosis
- 1 tab K-phos neutral 250mg Q hour x 5 doses
- Each tab contains phosphorus 8 mmol, Na 13 mEq, K1.1 mEq
- Recheck serum phosphate after last dose, and repeat dosing if continues to be <2mg/dl
- NOT able to take PO
- Minimize or eliminate all dextrose-containing IV solutions
- Aggressively treat acidosis
- Give 15 mmol of IV potassium phosphate over 2.5 hours (contains 22 mEq K)
- Peripheral administration may cause burning at injection site
- Consider central venous administration, if available
- Repeat dosing regimen if serum phosphate remains <2mg/dl
Serum phosphate <1mg/dl
- Minimize or eliminate all dextrose-containing IV solutions
- Exceptions: vasopressors, sedatives, analgesics, antibiotics, blood products, NS
- Aggressively treat acidosis
- Give 45 mmol of IV potassium phosphate over 7 hours (contains 66 mEq of K)
- Peripheral administration may cause burning at injection site
- Consider central venous administration, if available
- If patient can tolerate PO, ALSO follow steps 1 above
- Recheck serum phosphate after infusion
- Repeat IV administration if <1mg/dl
- Consider oral administration if >1mg and <2mg/dl
