Carboplatin calculator

The free online Carboplatin calculator estimates your Carboplatin dosage (mg) using the Calvert formula. These calculations are based on a person's estimated creatinine clearance level and the targeted AUC value.

The most critical concept to understand is the Calvert formula:

Calvert Formula

Carboplatin is a chemotherapy medication used to treat cancer. It is administered via intravenous injection, and approximately 70% of the drug is excreted in the urine within 24 hours. The dosage depends on kidney function, which is measured using the Calvert formula:

Total Dose (mg) = Target AUC × (GFR + 25)

Calvert formula

Where:

AUC: Target area under the concentration-time curve in mg/mL
GFR: Glomerular Filtration Rate, indicating kidney filtering capacity

Glomerular Filtration Rate (GFR)

The GFR estimates how much blood passes through the Glomeruli per minute. The Glomeruli are the tiniest filters in the kidneys, designed to remove waste from the blood. The Carboplatin calculator uses the Calvert formula to determine the correct dosage based on age, sex, and weight.

Glomerular Filtration Rate

Important Considerations for the Calvert Formula

When using the Calvert formula, keep the following in mind:

Not recommended for patients with GFR or CrCl < 15–20 mL/min
CrCl values can fluctuate; the formula may be inaccurate in such cases
Patients outside the normal weight range should not rely solely on this formula
Consider using multiple formulas to accurately estimate the dose for each patient

Carboplatin Clearance for Men and Women

Different formulas are used for men and women due to variations in body composition and renal function:

Male: Carboplatin Clearance = (0.134 × weight) + (218 × weight × (1 - 0.00457 × age) / serum creatinine)

Female: Carboplatin Clearance = (0.134 × weight) + 0.686 × (218 × weight × (1 - 0.00457 × age) / serum creatinine)

Finding GFR Using the Cockcroft-Gault Equation

The Cockcroft-Gault equation is commonly used to estimate GFR for Carboplatin dosing. You can also use the Carboplatin calculator for this.

For Men: GFR = [(140 − Age) × Weight] / (72 × Serum Creatinine)

For Women: GFR = 0.85 × GFR (male formula)

Where:

GFR = Glomerular Filtration Rate
Age (A) = Age in years
Weight (W) = Body weight
Cr = Serum Creatinine (mg/dL)

Glomerular Filtration Rate

Example of GFR

Consider we want to find the GFR of a 50-year-old man whose weight is 78 kg and has a serum creatinine of 1.2 mg/dL.

Solution:

GFR = [(140 − Age) × Weight] / (72 × Serum Creatinine)

GFR = [(140 − 50) × 78] / (72 × 1.2)

GFR = [90 × 78] / 86.4

GFR = 7020 / 86.4

GFR = 81.25 mL/min

You can verify this GFR using the Carboplatin calculator to ensure correct dosing.

How to Find the Carboplatin Dosage

Once you have the GFR, the Calvert formula can be applied to determine the optimal Carboplatin dosage for patients. The Carboplatin calculator can also compute this automatically.

Using a target AUC of 7 mg/mL/min:

Carboplatin dose (mg) = AUC × (GFR + 25)

Carboplatin dose (mg) = 7 × (81.25 + 25)

Carboplatin dose (mg) = 7 × 106.25

Carboplatin dose (mg) = 743.8

How to Find Ideal Body Weight (IBW)

The Cockcroft-Gault equation usually uses total body weight, but the advanced version uses Ideal Body Weight (IBW) or Adjusted Body Weight (ABW) for more accuracy, especially in patients whose actual weight deviates from IBW.

IBW Formulas:

IBW (males) = 50 kg + 2.3 × (height [inches] − 60)
IBW (females) = 45.5 kg + 2.3 × (height [inches] − 60)

Adjusted Body Weight (ABW)

The ABW formula is used for obese patients to calculate more accurate doses:

ABW (kg) = Ideal Body Weight + [0.4 × (Actual Body Weight − Ideal Body Weight)]

Alternative ABW formula: ABW (kg) = Ideal Body Weight + [0.3 × (Actual Body Weight − Ideal Body Weight)]

The ABW is used in AUC calculations for obese patients using the Carboplatin calculator.

Jelliffe Equation

The Jelliffe equation monitors changes in serum creatinine over time to assess renal function. The Carboplatin calculator uses creatinine clearance adjusted for Body Surface Area (BSA):

Male: (98 − 0.8 × (Age − 20)) / SCR × Patient’s BSA / 1.73 m²

Female: Multiply the above result by 0.9

Body Surface Area (BSA)

The BSA can be calculated according to a patient’s weight and height and is used in carboplatin dosing:

Average BSA for adult men: 1.9 m²
Average BSA for adult women: 1.6 m²
Average BSA for children (9 years old): 1.07 m²

For automatic calculations, the Body Fat & BSA calculator can assist in determining the accurate dose for patients.

BSA (m²) = √{ [height (cm) × weight (kg)] / 3600 }

Calculating the Carboplatin Dose:

Example: Consider a male patient aged 22 years, weighing 67 kg, with serum creatinine 5 mg/dL, height 67 inches (5'7"), and a target AUC of 5 mg/mL/min.

Solution:

BSA (m²) = √{ [height (cm) × weight (kg)] / 3600 }

BSA = 1.78 m²

IBW (males) = 50 kg + 2.3 × (height [inches] − 60)

IBW = 66.1 kg

ABW (kg) = IBW + [0.4 × (Actual body weight − IBW)]

ABW = 66.46 kg

Clearance Method	Calculated Clearance (mL/min)	Calculated Carboplatin Dose (mg)
Jelliffe	19.3	221
Jelliffe (adjusted for BSA)	19.8	224
Cockcroft & Gault (using IBW)	21.7	233
Cockcroft & Gault (using ABW)	21.8	234
Cockcroft & Gault (using ABW alternative eq)	21.8	234
Cockcroft & Gault (using actual body weight)	22	235

You can check all these calculations using the Carboplatin calculator.

Working of the Carboplatin Calculator

To use the carboplatin dose calculator:

Input:

Select gender
Enter age and weight
Enter serum creatinine level
Enter the target AUC
Click calculate

Output:

Displays Glomerular Filtration Rate (GFR)
Calculates maximum Carboplatin dose

FAQs

What does 25 mean in the Calvert formula?

Calvert formula: Dose = AUC × (GFR + 25)

The value 25 mL/min represents carboplatin's non-renal clearance.

What is the normal GFR value?

Normal GFR is > 90 mL/min/1.73 m², indicating proper kidney function. Values are calculated using the carboplatin AUC calculator.

What is the normal GFR for a 70-year-old?

GFR decreases with age. For a 70-year-old, the normal range is around 60 mL/min/1.73 m², measurable via the carboplatin calculator.

How is the chemo dose measured?

BSA must be calculated first:

BSA (m²) = √{ [height (cm) × weight (kg)] / 3600 }

The AUC calculation requires BSA; without it, precise dosing is not possible.

Does chemo consider your weight?

Yes. Actual body weight is compared to Ideal Body Weight (IBW) to calculate the correct dose. The carboplatin AUC dose calculation incorporates both actual and ideal weights.

Does chemo affect your face?

The skin color may change during chemotherapy. Some patients may experience redness on their face, while others may become pale due to a reduction in red blood cells.

Can chemo affect your vitality?

Chemotherapy can lower testosterone levels and reduce libido during treatment.

Conclusion:

When administering chemotherapy, it is essential to determine the correct Carboplatin dosage. Carboplatin is used to treat cancers such as lung, brain, and ovarian cancer. The carboplatin calculator helps calculate the precise dosage based on a patient’s age, sex, and body weight.

References:

From Wikipedia: Carboplatin – Medical uses
From Medscape: Dosing & Uses – Advanced Ovarian Carcinoma