Calcium and Phosphorus

Neonates and infants have high requirements for calcium and phosphorus to maintain adequate bone mineralization. An optimal ratio of calcium-to-phosphorus intake is 1.7:1 (by weight) or 1.3:1 (by molar ratio). In situations of fluid restriction, however, high concentrations of calcium and phosphorus may cause precipitation within the solution. These calcium-phosphorus complexes may cause phlebitis and life-threatening emboli. Calcium gluconate is the preferred salt for use in PN solutions since it dissociates less than chloride salts and thereby remains in solution more readily. Other factors favoring the formation of calcium-phosphorus precipitates include low amino acid content, low dextrose content, high temperature, and high pH. Since solution pH is primarily determined by amino acid concentration, increasing amino acid intake, the use of more acidic amino acid solutions, and/or the addition of L-cysteine are common strategies used to prevent precipitation. Typically, 40 mg of L-cysteine is added per gram of protein. It is also recommended that if a PN solution contains 1 percent or less amino acids, only calcium or phosphorus (not both) be added. Consultation with the phar-

inacy is encouraged when solutions of high calcium and phosphorus concentration are desired, and published nomograms are useful for specific compatibility information. A conservative estimate may be obtained by adding the sum of calcium and phosphorus concentrations (mmol/L): if the sum of these numbers exceeds 40, the risk of precipitation is high. It should be noted that these recommendations do not apply to total nutrient admixtures (so-called 3-in-l solutions) since calcium and phosphorus solubility is lower in these mixtures. It is therefore recommended that neonates not receive 3-in-l solutions.

Table 17-12. Suggested Intake of Trace Nutrients*

Weight Weight Element < 2 kg > 2 kg Comments

Table 17-12. Suggested Intake of Trace Nutrients*

Weight Weight Element < 2 kg > 2 kg Comments

Zinc

3 mg 1 mg

Increase dose with increased Intestinal losses

Manganese

50 pg 60 pg

Decrease dose with cholestatic liver disease

Copper

200 pg 200 pg

Decrease dose with cholestatic liver disease

Chromium

1.7 pg 2 pg

Increase dose with intestinal losses, and decrease with renal dysfunction

Iron'

1 mg/d (see text)

Monitor for anaphylaxis with initial infusion

Selenium'

1 -3 pg/kg/d max dose 30-40 pg/d

Reduce dose with renal disease (may have increased requirements with increased intestinal losses)

Carnitine'

8-16 mg/kg/d

Patients with primary carnitine deficiency will require higher doses

'Concentration per liter PN

'May be added after 30 days of NPO status and/or minimal enteral intake.

'Concentration per liter PN

'May be added after 30 days of NPO status and/or minimal enteral intake.

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Responses

  • sebastian
    What is a good calcium phosphorus ratio in a amino acid formula?
    7 months ago
  • Geronima
    How to increase solubility of calcium and phosphorus in PN?
    5 months ago
  • maunu
    How to replace phosphorus parenteral nutrition?
    2 months ago
  • kibra
    How to improve calcium phosphorus in PN?
    9 days ago

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