▸ About this calculator
Overview
This parenteral nutrition (PN) calculator is designed for use by neonatal dietitians and clinicians. It supports order entry for macronutrients, multivitamins, trace elements, and electrolytes, and generates a compounding recipe, osmolarity estimate, calcium/phosphate compatibility check, and electrolyte safety flags.
Important: This calculator provides estimates only. Osmolarity values, calcium/phosphate solubility limits, and compounding volumes are approximations based on published stock concentrations and reference equations. Institutional stock solutions vary in concentration, and formulas used here may not reflect your pharmacy’s specific products. All orders must be reviewed and verified by a qualified pharmacist and clinician prior to compounding. Local pharmacy protocols and compatibility data always take precedence over the estimates produced by this tool.
Amino Acid Products
| Product | Osmolarity | Region | Cysteine required |
|---|---|---|---|
| Primene 10% (CAN) | 780 mOsm/L | Canada | No — cysteine is already present in the formulation |
| TrophAmine 10% (USA) | 875 mOsm/L | United States | Yes |
| Premasol 10% sulfite-free (USA) | 865 mOsm/L | United States | Yes |
TrophAmine and Premasol are bioequivalent and therapeutically equivalent pediatric amino acid solutions. Both require supplementation with cysteine hydrochloride, a conditionally essential amino acid in neonates. Primene contains cysteine as part of its formulation and does not require additional supplementation.
Cysteine Hydrochloride (US only)
Cysteine HCl injection is available in the US at a concentration of 50 mg/mL. Osmolality: approximately 647 mOsm/kg (based on FDA NDA 210660 stability batch data; Exela Pharma Sciences / ELCYS).
The typical dose is 40 mg/g of amino acids, however the dose field is editable to accommodate institutional practice.
Cysteine supplementation raises the precipitation limit, allowing higher calcium and phosphate concentrations to be safely compounded. This is reflected in the Ca/Phos compatibility check when a cysteine dose is entered.
Lipid Emulsions
| Product | Composition | Region |
|---|---|---|
| SMOFlipid 20% | Soybean, MCT, olive, fish oil | Both |
| Intralipid 20% | Soybean oil | Both |
| ClinOleic 20% (CAN) | Olive oil / soybean oil (80:20) | Canada |
| Clinolipid 20% (USA) | Olive oil / soybean oil (80:20) | United States |
| Omegaven 10% | Fish oil (monotherapy) | Both |
ClinOleic and Clinolipid are the same formulation marketed under different brand names in Canada and the United States respectively (both manufactured by Baxter).
Multivitamins
| Product | Region |
|---|---|
| Infuvite Pediatric (USA) | United States |
| Multi-12/K1 Pediatric (CAN) | Canada |
Weight-based dosing tiers apply to both products:
| Weight | Dose |
|---|---|
| < 1500 g | 1.5 mL/day |
| 1500 g to < 3 kg | 3.25 mL/day |
| ≥ 3 kg | 5 mL/day |
Osmolarity values used in this calculator are provisional estimates and should be confirmed with the product manufacturer.
Trace Elements
| Product | Standard Dose | Maximum | Region |
|---|---|---|---|
| Micro+ TE Pediatric (CAN) | 1 mL/kg/day | 5 mL/day | Canada |
| Multrys (USA) | 0.3 mL/kg/day | 1 mL/day | United States |
For preterm infants < 3 kg receiving Micro+ TE Pediatric, the zinc provision of 250 mcg/kg/day may be insufficient. Additional zinc supplementation from a separate source may be required. Multrys dosing for infants < 0.4 kg has not been established; use clinical judgment.
Stock Concentrations
The following stock solution concentrations are used to calculate compounding volumes and osmolarity contributions. These are reference values only — stock concentrations vary between institutions and pharmacies. Always verify against your pharmacy’s specific products.
| Electrolyte | Stock Concentration | Osmolarity |
|---|---|---|
| Sodium chloride | 4 mmol/mL | 8.0 mOsm/mL |
| Sodium acetate | 4 mmol/mL | 8.0 mOsm/mL |
| Sodium phosphate | 4 mmol Na/mL · 3 mmol PO₄/mL | 7.0 mOsm/mL |
| Potassium chloride | 2 mmol/mL | 4.0 mOsm/mL |
| Potassium acetate | 2 mmol/mL | 4.0 mOsm/mL |
| Potassium phosphate | 4.4 mmol K/mL · 3 mmol PO₄/mL | 7.4 mOsm/mL |
| Calcium gluconate | 100 mg/mL (0.2324 mmol/mL) | 0.68 mOsm/mL |
| Magnesium sulfate 50% | 500 mg/mL (4.154 mmol/mL) | 4.06 mOsm/mL |
| Cysteine HCl (USA) | 50 mg/mL | ~0.647 mOsm/mL |
Dextrose Osmolarity
Dextrose osmolarity is calculated using the molecular weight of dextrose monohydrate (MW 198 g/mol):
Osmolarity (mOsm/L) = (D% / 100) × (1000 / 198) × 1000
This yields approximately 3535 mOsm/L for D70% stock, consistent with published reference values (~3532 mOsm/L).
Osmolarity Estimates
Osmolarity values generated by this calculator are estimates only. Actual measured osmolality of a compounded PN bag will differ due to variations in stock solution concentrations, non-ideal solution behaviour at high concentrations, and additive interactions between solutes.
Osmolarity thresholds used in this calculator (≥900 mOsm/L: consider central access; >1200 mOsm/L: central access required) are based on commonly cited clinical guidelines. Institutional policies may specify different thresholds.
Electrolyte Safety Flags
For patients weighing less than 10 kg, the calculator flags electrolyte doses exceeding the following upper limits (ESPGHAN 2018):
| Ion | Upper limit |
|---|---|
| Sodium (Na) | 5 mmol/kg/day |
| Potassium (K) | 3 mmol/kg/day |
| Calcium (Ca) | 1.75 mmol/kg/day |
| Phosphate (PO₄) | 2.5 mmol/kg/day |
| Magnesium (Mg) | 0.2 mmol/kg/day |
Flags are informational only. Doses above these thresholds may be clinically appropriate — the flag is intended as a prompt to verify intent, not a hard stop.
Calcium/Phosphate Compatibility
Calcium and phosphate compatibility results are estimates only. Actual solubility in a compounded bag depends on temperature, order of mixing, pH, specific salt forms used, and exact stock concentrations at your institution. Results should always be reviewed by a compounding pharmacist.
Compatibility is assessed using the equations published by Anderson et al. (2022). TrophAmine, Premasol, and Primene are all assigned AAF = 200. Primene is a conservative estimate — published data suggest Primene may allow higher Ca/Phos concentrations than TrophAmine at equivalent AA concentrations.
When cysteine is entered (US formulations), the precipitation limit increases per the Anderson equations. For Canadian formulations using Primene, CYS = 0 is used, producing a more conservative limit. An 80% safety margin is applied: the calculator flags solutions approaching 80% of the precipitation limit (caution) and exceeding 100% (incompatible).
Ca:Phosphate molar ratio is displayed alongside the compatibility check. A ratio of 1.3:1 to 1.7:1 (Ca:PO₄, molar) is generally recommended for neonatal PN, though this should be interpreted alongside absolute doses and clinical context.
References
- Anderson C, et al. Calcium and Phosphate Solubility Curve Equation for Determining Precipitation Limits in Compounding Parenteral Nutrition. JPEN. 2022. PMID: 36340622
- Fitzgerald KA, MacKay MW. Calcium and phosphate solubility in neonatal parenteral nutrient solutions containing TrophAmine. Am J Hosp Pharm. 1986;43(1):88–93.
- Olthof ED, et al. Calcium/Phosphate Solubility Curves for Premasol and Trophamine Pediatric Parenteral Nutrition Formulations. JPEN. 2019. PMID: 30837814
- Thabet R, et al. Doubling calcium and phosphate concentrations in neonatal parenteral nutrition solutions using monobasic potassium phosphate. JPEN. 2005. PMID: 16537340
- Koletzko B, et al. Guidelines on Paediatric Parenteral Nutrition (ESPGHAN). J Pediatr Gastroenterol Nutr. 2018;67(Suppl 2):S1–S222.
- FDA NDA 210660 Chemistry Review — Cysteine Hydrochloride Injection USP 50 mg/mL (Exela Pharma Sciences / ELCYS).
- Product monographs: Infuvite Pediatric, Multi-12/K1 Pediatric, Micro+ TE Pediatric, Multrys, Primene 10%, TrophAmine 10%, Premasol 10%.