Health minister Lord O’Shaughnessy has resigned from his post as Parliamentary under secretary of state in the House of Lords for family reasons.

Lord O’Shaughnessy posted his resignation letter, dated 20 December, on social media yesterday, in which he revealed his decision to stand down at the end of the month.

He was appointed minister in December 2016. He was responsible for Brexit health policy, life sciences, medication and regulation as well as data, technology and NHS estates policy.

In his resignation letter to the prime minister, he wrote: “With regret, I am writing to inform you of my intention to stand down as Parliamentary under secretary of state for health at the end of December 2018 due to family circumstances.”

He praised the prime minister for her commitment to the NHS and her “steadfast leadership” in negotiating Britain’s withdrawal from the EU.

He pledged his loyalty to the prime minister and offered to serve in her government again, should his circumstances change.