Pediatric Dosage Calculator
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padding: 20px;
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margin: 20px auto;
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padding: 30px;
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#result {
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.input-group {
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.input-group label, .input-group input[type="number"], .input-group select {
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.peds-calc-container {
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Pediatric Dosage Calculator
Understanding Pediatric Dosage Calculations
Calculating the correct medication dosage for pediatric patients is critical for ensuring treatment efficacy and patient safety. Unlike adults, children have different metabolic rates, organ development, and body compositions, meaning dosages cannot simply be scaled down from adult prescriptions. Pediatric dosages are typically based on the child's weight or, in some cases, body surface area (BSA).
The Formula for Weight-Based Dosing
The most common method for calculating pediatric dosages involves the following steps:
- Determine Patient Weight: Obtain the child's current weight. Ensure the unit of measurement (kilograms or pounds) is noted.
- Convert Weight (if necessary): If the medication dosage is specified in mg/kg or mcg/kg, and the patient's weight is in pounds, convert pounds to kilograms using the conversion factor:
1 kg = 2.20462 lb.
- Calculate the Absolute Dose: Multiply the patient's weight (in kilograms) by the prescribed medication dosage per kilogram. This gives you the total amount of the medication the child needs for one dose. The formula is:
Absolute Dose = Patient Weight (kg) * Medication Dosage (e.g., mg/kg)
- Calculate the Volume to Administer: This step uses the calculated absolute dose and the concentration of the available medication. The formula is:
Volume to Administer (mL) = Absolute Dose / Medication Concentration (e.g., mg/mL)
Example Calculation
Let's consider a scenario:
- Patient Weight: 44 lb
- Medication Dosage: 10 mg/kg
- Medication Concentration: 50 mg/mL
Step 1 & 2: Convert Weight
Convert pounds to kilograms: 44 lb / 2.20462 lb/kg ≈ 20 kg
Step 3: Calculate Absolute Dose
Absolute Dose = 20 kg * 10 mg/kg = 200 mg
Step 4: Calculate Volume to Administer
Volume to Administer = 200 mg / 50 mg/mL = 4 mL
Therefore, the child should receive 4 mL of the medication.
Important Considerations:
- Unit Consistency: Always ensure that units are consistent throughout the calculation. For example, if the medication is dosed per kilogram, the patient's weight MUST be in kilograms.
- Concentration Verification: Double-check the concentration of the medication vial you are using. Different formulations of the same drug can have varying concentrations.
- Pediatric Dosages are Guidelines: This calculator provides a calculated dose based on standard formulas. However, clinical judgment, patient-specific factors (like kidney or liver function), and physician orders always take precedence. Always consult with a healthcare professional for definitive dosage decisions.
- Rounding: Depending on the medication and clinical practice, calculated volumes may need to be rounded to the nearest practical increment (e.g., 0.1 mL or 0.5 mL).
function calculateDosage() {
var patientWeight = parseFloat(document.getElementById("patientWeight").value);
var weightUnit = document.getElementById("weightUnit").value;
var medicationDosage = parseFloat(document.getElementById("medicationDosage").value);
var dosageUnit = document.getElementById("dosageUnit").value;
var medicationConcentration = parseFloat(document.getElementById("medicationConcentration").value);
var concentrationUnit = document.getElementById("concentrationUnit").value;
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = 'Result will appear here.'; // Clear previous result
// — Input Validation —
if (isNaN(patientWeight) || patientWeight <= 0) {
resultDiv.innerHTML = "Please enter a valid patient weight.";
return;
}
if (isNaN(medicationDosage) || medicationDosage <= 0) {
resultDiv.innerHTML = "Please enter a valid medication dosage.";
return;
}
if (isNaN(medicationConcentration) || medicationConcentration <= 0) {
resultDiv.innerHTML = "Please enter a valid medication concentration.";
return;
}
// — Unit Handling & Conversion —
var weightInKg = patientWeight;
if (weightUnit === "lb") {
weightInKg = patientWeight / 2.20462;
}
var absoluteDose = 0;
var dosageUnitForCalculation = dosageUnit.split('/')[0]; // e.g., 'mg' or 'mcg'
if (dosageUnitForCalculation === "mg") {
absoluteDose = weightInKg * medicationDosage;
} else if (dosageUnitForCalculation === "mcg") {
absoluteDose = weightInKg * medicationDosage;
} else {
resultDiv.innerHTML = "Unsupported dosage unit.";
return;
}
var volumeToAdminister = 0;
var concentrationUnitForCalculation = concentrationUnit.split('/')[0]; // e.g., 'mg' or 'mcg'
if (dosageUnitForCalculation === concentrationUnitForCalculation) {
volumeToAdminister = absoluteDose / medicationConcentration;
} else if (dosageUnitForCalculation === "mg" && concentrationUnitForCalculation === "mcg") {
// Convert concentration from mcg/mL to mg/mL
var concentrationInMgPerMl = medicationConcentration / 1000;
volumeToAdminister = absoluteDose / concentrationInMgPerMl;
} else if (dosageUnitForCalculation === "mcg" && concentrationUnitForCalculation === "mg") {
// Convert concentration from mg/mL to mcg/mL
var concentrationInMcgPerMl = medicationConcentration * 1000;
volumeToAdminister = absoluteDose / concentrationInMcgPerMl;
}
else {
resultDiv.innerHTML = "Mismatched units for dosage and concentration.";
return;
}
// — Display Result —
var finalVolume = volumeToAdminister.toFixed(2); // Round to 2 decimal places
resultDiv.innerHTML = "" + finalVolume + " mL" + "
Volume to administer";
}