A Twin Cities podiatrist with a history of malpractice suits and billing irregularities lost his license after the state determined he improperly billed more than $93,000 to Medica and HealthPartners.

The Minnesota Board of Podiatric Medicine revoked Dr. Robert Mullin’s license after he used incorrect codes to bill the insurance companies for more than 200 nerve sensory procedures not covered by the providers.

The revocation was the first for the podiatric board since 2003, but the board has disciplined Mullin before. He received a reprimand in 2005 after he falsely advertised services he did not offer and did not provide refunds to several patients. The board also noted complaints about Mullin’s surgical practices, which had resulted in seven malpractice suits since 1997.

In 2011, the Star Tribune reported how former patients continued to complain about Mullin’s billing practices even after the reprimand. Mullin could not be reached for comment Thursday.

According to an order released Thursday by the board, Mullin performed hundreds of “Pressure Specified Sensory Device” exams and then billed the insurance companies using a code assigned for a different procedure. When Medica and HealthPartners discovered the errors and demanded repayment, Mullin sent letters to patients in an attempt to get them to pay.

In the letter he wrote, “Your insurance initially paid for the claim, but after reviewing the code, they took the money back and informed us that you would be responsible for any charges,” the order said.

He addedthat “I am willing to write off a substantial portion of the original charge, $1,000, leaving the balance owed for the test at $600.”

Mullin sent the letter to 470 patients, 250 of whom had not received the sensory exam during the period for which Medica and HealthPartners were seeking reimbursement.

Had he collected from the 470 patients, Mullin would have received $282,000, despite the fact that the insurance companies were only seeking $93,712, the order said.

The board’s order also stated that Medica never told Mullin that his patients would be responsible for the charges. Medica also pointed out that Mullin had not gotten signed permission forms from patients, a requirement for procedures not covered by their insurance company, the order said.

Ultimately, Mullin refunded the money he had received from patients who had paid him after receiving the letter, according to the order.

The order said that Mullin can reapply for his license in five years if he can demonstrate that “he is capable of practicing podiatric medicine in a fit, competent and ethical manner” and pays a $15,000 fine.