hCG Reconstitution Calculator

An hCG reconstitution calculator converts the stated strength of an hCG vial into a measurable liquid concentration after the medication has been mixed with a specified volume of diluent.

Once the concentration is known, the calculator can determine how many millilitres correspond to the prescribed number of international units and how that liquid volume translates to the markings on a U-100 insulin syringe.

It can also calculate how many complete doses are mathematically available from the vial based on the values entered.

This is a mathematical conversion tool. It does not prescribe hCG, choose a treatment dose or confirm whether a particular preparation method is appropriate.

Some men receiving Testosterone Replacement Therapy may also be prescribed human chorionic gonadotropin, commonly shortened to hCG, as part of an individual treatment plan.

Testosterone supplied externally can suppress signalling through the hypothalamic-pituitary-gonadal axis. LH and FSH can fall substantially, reducing stimulation of the testes and potentially suppressing sperm production.

hCG acts through the LH receptor and may therefore be discussed where testicular function, fertility or future family planning is clinically relevant.

It is not automatically required for every person receiving TRT. Whether hCG is appropriate, the dose used and the monitoring required should be decided by the clinician responsible for treatment.

The calculation happens in three stages. First the concentration of the prepared vial is established, then the liquid volume for the entered dose is calculated, and finally that volume can be translated into a U-100 syringe marking.

The following example demonstrates the mathematics only. It is not a dosing recommendation.

Dividing 5,000 IU by 2 mL gives a concentration of 2,500 IU per mL.

Dividing the example dose of 250 IU by 2,500 IU/mL gives a liquid volume of 0.10 mL.

Because a U-100 syringe contains 100 marked units per millilitre, 0.10 mL corresponds to 10 marked units on the syringe.

One of the most common sources of confusion when preparing hCG is that IU, millilitres and syringe units all describe different things.

• IU describes the stated biological activity or strength of the hCG.
• mL describes the actual liquid volume being drawn.
• U-100 syringe units are volume markings where 100 marked units equal 1 mL.

A syringe marking is therefore not the same thing as a medication dose in IU.

The number of IU represented by a particular syringe marking depends entirely on the concentration of the prepared solution.

If the same vial is mixed with a different amount of diluent, the concentration changes and the syringe volume required for the same IU dose changes with it.

Enter the exact number of millilitres used to prepare your own vial. Do not choose a different volume simply because it creates a more convenient syringe marking.

The appropriate diluent, preparation method, storage requirements and period of use after reconstitution depend on the specific product supplied.

Follow the instructions provided by your prescribing clinic, pharmacy or medication manufacturer.

If your stated preparation volume is not shown in the preset menu, the calculator allows a custom volume to be entered.

If any part of the supplied preparation instructions is unclear, ask your pharmacist or prescriber to confirm it before preparing the medication.

• The calculation is only as accurate as the values entered.
• The calculator does not verify the medication vial, prescription or pharmacy label.
• The calculator does not recommend an hCG dose.
• Displayed U-100 syringe units are rounded to the nearest whole unit.
• Different syringe types can use different capacities and graduation markings.
• The tool does not provide sterile preparation or injection training.
• Storage instructions can differ depending on the supplied product and diluent.
• The calculated number of complete doses does not account for unavoidable medication loss or residual liquid remaining in the vial or syringe.

A clinician or pharmacist should review any calculation you are uncertain about. Never change your prescribed dose solely because of the output of an online calculator.