GPs have defended charging some medical card holders for blood tests.
Dr Austin Byrne, of the Irish Medical Organisation, said the medical card contract, which is now more than 40 years old, was not designed to cover the amount of routine blood tests for patients which are now needed.
The free medical card just covers blood tests to diagnose illness and not routine monitoring and screening, he said.
GPs are increasingly opting to charge for the blood tests and advise patients who do not want to pay that they can get the service free in their hospital instead.
The cost varies, but it can be as much as €20. Some GPs have had to issue refunds after patients complained to the HSE.
The issue is to be looked at in negotiations on a new GP contract, which are now underway.
The Department of Health said the HSE has advised GPs that where a blood test forms part of the investigation or necessary treatment of a patient's symptoms or conditions, this should be free of charge for patients who hold a medical card or GP visit card.