HCG Doubling Time Calculator

Formula

To calculate the HCG doubling time:

\[ DT = \frac{t_2 - t_1}{\log_2 \left(\frac{HCG_2}{HCG_1}\right)} \]

Where:

\( DT \) is the HCG doubling time (hours)
\( t_1 \) is the time of the first measurement (hours)
\( t_2 \) is the time of the second measurement (hours)
\( HCG_1 \) is the HCG level at the first measurement (mIU/mL)
\( HCG_2 \) is the HCG level at the second measurement (mIU/mL)

HCG Doubling Definition

HCG doubling refers to the process where the levels of the hormone human chorionic gonadotropin (HCG) double approximately every 48 to 72 hours during the early stages of pregnancy. This hormone is produced by the placenta after implantation, and its rapid increase is often used as an early indicator of pregnancy. The rate of HCG doubling can be used to estimate the age of the fetus and monitor the health of the pregnancy. A slower rate of doubling may indicate potential issues such as miscarriage or ectopic pregnancy.

Example Calculation 1

Let's assume the following values:

Time of First Measurement (t1) = 0 hours
Time of Second Measurement (t2) = 48 hours
HCG Level at First Measurement (HCG1) = 100 mIU/mL
HCG Level at Second Measurement (HCG2) = 400 mIU/mL

Using the formula:

\[ DT = \frac{48 - 0}{\log_2 \left(\frac{400}{100}\right)} = \frac{48}{\log_2 (4)} = \frac{48}{2} = 24 \text{ hours} \]

The HCG doubling time is 24 hours.

Example Calculation 2

Let's assume the following values:

Time of First Measurement (t1) = 24 hours
Time of Second Measurement (t2) = 72 hours
HCG Level at First Measurement (HCG1) = 150 mIU/mL
HCG Level at Second Measurement (HCG2) = 600 mIU/mL

Using the formula:

\[ DT = \frac{72 - 24}{\log_2 \left(\frac{600}{150}\right)} = \frac{48}{\log_2 (4)} = \frac{48}{2} = 24 \text{ hours} \]

The HCG doubling time is 24 hours.