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Intravenous Dilution Guidelines

Potassium Phosphate /  Sodium phosphate

The authors make no claims of the accuracy of the information contained herein; and these suggested doses and/or guidelines are not a substitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in the preparation of this document shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.    PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.

Usual Diluents

NS, D5W

Standard Dilutions   [Amount of drug] [Infusion volume] [Infusion rate]

Review dosing below
Floors:
[15 mmol] [250 ml] [4-6 hours]
[30 mmol] [500 ml] [8 hours]

ICU's:  ~7.5 mmol/hour
[15 mmol] [100 ml] [2 hours]
[30 mmol] [250 ml] [4 - 8 hours]

General guidelines:
1] Potassium phosphate preferred for patients with serum potassium less than 4 mmol/L.
2] Sodium phosphate is preferred for the following patients:  *Patients who received recent K+ infusion(s) or  *Serum potassium greater than 4 mmol/L.

Stability / Miscellaneous

EXP: 1 DAY (RT).

Potassium Phosphate
[Supplied: 15 mmol PO4 (and 22 meq K+) / 5 ml vial].

Sodium Phosphate
[Supplied: 15 mmol PO4 (and 20 meq Na+) / 5 ml vial].

Normal range: 2.5 to 4.5 mg/dl.

Dosing:
*Mild to moderate hypophosphatemia (1.3 to 2.5 mg/dl): Oral therapy adequate: 2.5 to 5 mg/kg of PO4 bid-tid or approximately 1-2 pkts (250 mg=8 mmol/packet) of Neutra-phos bid to tid.
Manufacturer recommends: 1-2 packets 4 times daily (after meals and at bedtime)

*Severe hypophosphatemia (PO4 < 1.2 mg/dl): Give 0.16 to 0.25 mmol/kg IVPB q6 to 8 hours until serum level reaches 2 mg/dl.

Doses as high as 0.5 mmol/kg may be given if level is below 0.7 mg/dl.

*Alternatively: (level < 2 mg/dl) (ICU patient): give 15 mmol NaPO4 in 100 ml NS over 2 to 6 hrs; repeat q6h to max of 45 mmol/24 hours. [Crit Care Med 1995;23:1204.]


Other: Support for higher doses.
Source generally followed by direct quotes:

1] Lexi-Drugs OnlineTM , Hudson, Ohio: Lexi-Comp, Inc.; 2015; Accessed: January 28, 2015.
Critically-ill adult patients receiving concurrent enteral/parenteral nutrition:
*Round doses to nearest 7.5 mmol.   *If pt receiving phosphate-containing parenteral nutrition - do not exceed [15 mmol/L] in final parenteral nutrition admixture.

Consider using adjusted body weight if patient >30% over IBW.  Equation listed: [IBW + 0.25 (actual body weight - IBW)].  
"Low dose, serum phosphorus level 2.3-3 mg/dL (0.74-0.96 mmol/L): 0.16-0.32 mmol/kg over 4-6 hours.  Intermediate dose, serum phosphorus level 1.6-2.2 mg/dL (0.51-0.71 mmol/L): 0.32-0.64 mmol/kg over 4-6 hours  High dose,, serum phosphorus <1.5 mg/dL (<0.5 mmol/L): 0.64-1 mmol/kg over 8-12 hours."


2] Imel EA, Econs MJ. Approach to the Hypophosphatemic Patient. The Journal of Clinical Endocrinology and Metabolism. 2012;97(3):696-706. doi:10.1210/jc.2011-1319.

"Acute severe hypophosphatemia in hospitalized patients may contribute to respiratory or hemodynamic instability, and a 2- to 4-fold increase in mortality is reported in prospective and retrospective studies."
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"Intravenous phosphate should be used cautiously. Treatment of severe acute hypophosphatemia is based on small uncontrolled adult studies with only 10 to 16 patients with serum phosphate below 1.5 mg/dl per study."
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"The response to iv phosphate is highly variable and not easily predicted by initial levels. When providing iv phosphate, serum calcium, phosphate, potassium, magnesium, and creatinine should be closely monitored (at least every 6 h), and telemetry is recommended. The most significant risks of iv phosphate are acute severe life-threatening hypocalcemia, with tetany, seizures, electrocardiogram changes and shock, and overtreatment resulting in hyperphosphatemia and hyperkalemia (because of potassium phosphate formulations)"


3] Clark CL, Sacks GS, Dickerson RN, Kudsk KA, Brown RO. 1995. Treatment of hypophosphatemia in patients receiving specialized nutrition support using a graduated dosing scheme: results from a prospective clinical trial. Crit Care Med 23:1504-1511.

"Patients were enrolled into one of three categories based on their serum phosphorus concentration: mild hypophosphatemia (2.3 to 3 mg/dL [0.74 to 0.97 mmol/L]), moderate hypophosphatemia (1.6 to 2.2 mg/dL [0.52 to 0.71 mmol/L]), or severe hypophosphatemia (< 1.5 mg/dL [< 0.48 mmol/L]). Each  patient received one intravenous phosphorus bolus dose, based on the assigned category of hypophosphatemia, according to a graduated dosing scheme: 0.16 mM/kg (mild), 0.32 mM/kg (moderate), or 0.64 mM/kg (severe). Serum/blood concentrations of phosphorus, calcium, albumin, magnesium, urea nitrogen, and creatinine were measured for three consecutive days."
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"The dose of intravenous phosphorus was diluted in either 100 mL (mild and moderate groups) or 150 mL (severe group) of normal saline or 5% dextrose in water and infused over 4 to 6 hrs (mild and moderate groups), or 8 to 12 hrs (severe group). The dose was administered as either the
sodium or potassium salt. Patients with a serum potassium concentration of less than 4 mmol/L received the potassium salt, whereas patients with a serum potassium concentration of more than 4 mmol/L received the sodium salt. If the patient had already received a potassium bolus for a low
serum potassium concentration that morning, the sodium salt was administered. The dose of phosphorus was infused in the late morning or early afternoon, after the laboratory determination that was performed at 0300 hrs."
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"The first prospective clinical trial to determine the safety and efficacy of parenteral phosphorus replacement therapy in patients with severe hypophosphatemia was conducted by Vannatta and co-workers [24]. Ten adult patients with serum phosphorus concentrations of less than 1 mg/dL (less than 0.32 mmol/L), normal renal function, normal serum electrolytes, and no evidence of tissue necrosis received 9 mM of potassium phosphate every 12 hrs. Significant improvements in serum phosphorus concentrations at 12 hrs were observed. However, serum concentrations of more than 1 mg/dL (more than 0.32 mmol/L) were not achieved for all ten patients by 36 hrs. At 48 hrs, 40% of the patients had not achieved normal serum concentrations of phosphorus. No adverse events were noted from the intravenous phosphorus infusion."  [24. Vannatta JB, Whang R, Papper S: Efficacy of intravenous phosphorus therapy in the severely hypophosphatemic patient. Arch Intern Med 1981; 141:885-887]

"CONCLUSION: The graduated dosing scheme of phosphorus replacement therapy is both safe and efficacious in patients receiving specialized nutrition support."


4] Brown KA, Dickerson RN, Morgan LM, et al, “A New Graduated Dosing Regimen for Phosphorus Replacement in Patients Receiving Nutrition Support,”
JPEN J Parenter Enteral Nutr, 2006, 30(3):209-14
. [PubMed 16639067]

"Methods: Seventy-nine adult trauma patients with hypophosphatemia (serum phosphorus concentration </= 0.96 mmol/L) receiving nutrition support received an IV dose of phosphorus on day 1 according to the serum concentration of phosphorus: 0.73-0.96 mmol/L (0.32 mmol/kg, low dose), 0.51- 0.72 mmol/L (0.64 mmol/kg, moderate dose), and </= 0.5 mmol/L (1 mmol/kg, high dose). The IV phosphorus bolus dose was administered at 7.5 mmol/hour. Generally, patients with a serum potassium concentration < 4 mmol/L received potassium phosphate and patients with a serum potassium concentration >/=4 mmol/L received sodium phosphate. Patients who still had hypophosphatemia on day 2 were dosed using the new dosing algorithm by the nutrition support service according to that day’s serum concentration of phosphorus, or empirically by the trauma service. "

"Conclusions: This weight-based phosphorus-dosing algorithm is safe for use in critically ill patients receiving nutrition support. The moderate- and severe-dose regimens effectively increase serum phosphorus concentrations."



Disclaimer
The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in the preparation of this program shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.  PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.
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