Phosphate Supplementation

Summary Phosphorus Content
K-Phos ® Neutral Tablets K-PHOS® ORIGINAL
Neutra-Phos ® Hypophosphatemia

Summary top of page

Phosphate Summary:
Phosphorus: (hypophosphatemia)
-Oral: ~2 packets (16 mmol) Neutra-Phos qid (with meals and at bedtime).
RDA: (1 packet qid = 1 gram phosphorus = 32 mmol)

Phosphate supplement: Oral: Elemental phosphorus 250 to 500 mg 4 times/day after meals and at bedtime.  
P (MW=31).  250mg = 8.06 mmol.   RDA (adults): 800-1200mg phosphorus/day =  ~26 - 38 mmol/day.  (pregnant/lactating women: 1200mg/day).

Phosphorus Content top of page

Product P (mmol) Na+ meq K+ meq
Neutra-Phos®  (capsule /pkt) 8 7.1 7.1
Neutra-Phos K® (capsule /pkt) 8 0 14.25
Skim milk per 8 oz (1 cup) 8 3 5
K-Phos ® Neutral  (tablet) 8 13 1.1
Fleet® Phospho Soda (soln) /ml 4.15 4.82 0
Potassium Phosphate (ml) 3 0 4.4
Sodium Phosphate (ml) 3 4.0 0
3 mmol = 93 mg phosphorus (MW = 31)

K-Phos ® Neutral Tablets top of page

K-hos ® Neutral Tablets: [ Each tablet contains approximately 250 mg of phosphorus, 298 mg of sodium (13.0 mEq) and 45 mg of potassium (1.1 mEq).]

 Dosage and administration:
Tablets should be taken with a full glass of water, with meals and at bedtime. Adults: One or two tablets four times daily. Pediatric Patients over 4 years of age: One tablet four times daily.

K-PHOS® ORIGINAL top of page

K-PHOS® ORIGINAL (Sodium Free): Each tablet contains potassium acid phosphate 500 mg [~ 114 mg (3.68 mmol) of phosphorus and 144 mg of K+ ( 3.7 mEq)]. ACTIONS: highly effective urinary acidifier.
: For use in patients with elevated urinary pH. Helps keep calcium soluble and reduces odor and rash caused by ammoniacal urine. Also, by acidifying the urine, it increases the antibacterial activity of methenamine mandelate / hippurate. DOSAGE:: Two tabs ( dissolved in 6-8 oz. of water) 4 times daily with meals and at bedtime. 

Neutra-Phos ® top of page

Neutra-Phos ®: (mix with at least 2.5 ounces (75 ml) of water/juice).
Dosage: 1 pkt four times daily with meals and at bedtime. Mild laxative effect possible.
[1 packet equivalent to elemental phosphorus 250 mg (~8 mmol), sodium 164 mg (7.1 mEq), and potassium 278 mg (7.1 mEq) per packet].

Dave's Tip: Remember that 1 pkt qid = RDA (1000 mg Phosphorus).
Table below (oral therapy for hypophosphatemia) shows that ~2 pkt's qid for treatment and 1 pkt for supplementation. [0.2 mmol x 70kg x 4 (e.g q6h) = 56 mmol = ~14 mmol (2 pkts) qid]

Hypophosphatemia  top of page

NORMAL LEVELS: 2.4 - 4.5 mg/dl (0.8 - 1.5 mmol/L)
Causes:   Decreased intake: malnutrition, malabsorption, vitamin D deficiency, phosphate binders, alcoholism.   Shifts from serum into cells: respiratory alkalosis, refeeding, hyperalimentation, effects of insulin/glucagon/androgens.  Increased urinary secretion: renal tubular defect, DKA.

Signs (generally seen only with total body depletion and serum PO4 < 1 mg/dL): weakness, rhabdomyolysis, respiratory compromise/failure, CHF, paresthesias, confusion, stupor, seizures, coma, hemolysis, platelet dysfunction, metabolic acidosis.

Therapy: Determine Ca x PO4 product before administering phosphorus:  If the product is greater than 60 mg/dl, there is a risk of calcium phosphate precipitation in the cornea, lung, kidney, cardiac conduction system, and blood vessels. 

Oral therapy:  For Phosphorus > 1 mg/dl (>0.3 mmol/L), oral therapy may be used.
1-2 tabs/pkts (8-16 mmol)  TID-QID.  
   [0.2 mmol x 70kg x 4 (e.g q6h) = 56 mmol = ~14 mmol (2 pkts) qid]

Estimated Phosphorus Requirements  top of page
(0.2-0.3 mmol/kg q6h = number of packets of Neutra-Phos®/24 hrs)
Patient weight  # pkts/24hr 0.2 -0.3 mmol/24hr 0.25 mmol/kg
60 kg 6 - 9   15
70 7 - 10.5 56-84 (14-21 mmol q6h) 17.5
80 8 - 12 64-96 (16-24 mmol q6h) 20
90 9 - 13.5 72-108 (18-27 mmol q6h) 22.5
100 10 - 15 80-120 (20-30 mmol q6h) 25
As a guideline, the phosphorus level will increase by an average of 1.2 mg/dl with a dose of 0.25mmol/kg.  Monitoring (IV): Phosphorus levels should be drawn at the end of the infusion and should always be drawn prior to any additional doses administered.     

For Phosphorus < 1 mg/dl (< 0.3mmol/L).
Acute decreases in PO4: 0.25 mmol/kg IBW*  (infuse over 4-6 hours)
Chronic depletion of PO4: 0.5 mmol/kg IBW* (infuse over 6 hours)
Renal insufficiency (CrCL <20ml/min): reduce dose by 50%.

Floors: KPhos or NaPhos 15 mmol/250 ml
ICU's:  KPhos or NaPhos 15 mmol/100ml NS/D5W over 2 hours centrally. (This method of administration is NOT recommended if: total calcium is < 7.5 mg/dL or > 11 mg/dL (corrected for albumin**) phosphorus is > 2 mg/dL OR significant renal dysfunction (Clcr < 10 ml/min).

Note: Phosphorus has historically been administered over 4 to 6 hours due to the potential risk associated with high doses and rapid administration (i.e., hypocalcemia, hypotension, metastatic calcification, renal failure). However, most of this data comes from cases of hypercalcemia treated with large doses of intravenous phosphates in which phosphorus levels were typically normal. More aggressive electrolyte replacement is not considered as risky.
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