In October 2025, we held a webinar to celebrate the work of Consultant Endocrinologist, Prof John Lazarus. Colleagues from Cardiff University and across the globe came together to explore his outstanding contributions to advancing the understanding of thyroid disease over nearly 50 years as a doctor, researcher and during his very active retirement. We take a look at some highlights from his long, illustrious career and how they have improved things for people living with thyroid conditions.

Making patients’ voices heard

From the early days of our charity back in the 1990s, John has been a true advocate of our work. John was instrumental in opening doors for our founder, Janis Hickey, to represent patients in projects ranging from pregnancy to iodine deficiency. It is thanks to John that we were able to develop our standing and influence with medical advisors and scientists. Most importantly, this has helped ensure patients’ experiences and concerns are considered in clinical practice and research.  John has also supported our work as medical advisor and trustee and continues to be involved as a patron.

“Without John and his dedication, generosity and insight, our small charity would not have been able to grow and achieve all it has done for the thyroid community and those who support them.” Julia Priestley. CEO BTF

Thyroid eye disease

John strongly believes that this distressing eye condition is best managed through the coordinated management of thyroid dysfunction and the orbitopathy (a condition affecting the tissues around the eyes). So along with other like-minded people, he brought together colleagues from endocrinology and ophthalmology  to found the European Group on Graves’ Ophthalmopathy (EUGOGO) Working Group in 1999. This helped to establish multidisciplinary joint thyroid eye clinics throughout Europe to improve how patients are assessed and treated. This paved the way for standardised care in the UK through the TEAMeD project, which sets out a framework for diagnosis and treatment and has helped countless TED patients to receive earlier diagnosis and care.

Postpartum thyroiditis

Another of John’s research interests was postpartum thyroiditis. This is a temporary inflammatory thyroid disorder that occurs in some women after pregnancy and is more common in women with thyroid autoantibodies.

Through his research, John highlighted the clinical importance of this condition, which had previously largely gone unrecognised by endocrinologists. John proved that postpartum thyroiditis occurs in around 5% of pregnancies and that it recurs in up to 70% of women after subsequent pregnancies. His research also confirmed that up to 50% of women will develop long-term hypothyroidism after postpartum thyroiditis.

This early research helped ensure this condition is picked up earlier in postpartum women and that they receive the appropriate monitoring and, where necessary, treatment. We are pleased to see that guidelines for its management are included in the 2025 Royal College of Obstetricians and Gynaecologists (RCOG) Green-top Guideline on the Management of Thyroid Disorders in Pregnancy.

Iodine

Later in his career, John developed a keen research interest in dietary iodine and its important role in the health of a population. For example, low iodine intake in pregnancy may affect foetal brain development.

Although in retirement, from 2012 to 2020 John was Regional Coordinator for West and Central Europe for the Iodine Deficiency Disorder Global Network. He was also a founder member and the lead of the UK Iodine Group. In this capacity, John lobbied hard for the iodisation of salt to help address iodine deficiency in the general population (i.e. people without thyroid conditions). Despite the many frustrations of coordinating this across Europe, John and colleagues did have some success in getting iodised salt on the supermarket shelves in many European countries, including the UK.

Frustratingly, the popularity of diets which exclude iodine-rich foods, such as eggs, dairy and fish, has contributed to the UK’s iodine intake to fall further behind that of many developing countries in recent years. This has prompted his former colleague, Dr Peter Taylor, Cardiff University and other UK experts to recently write a letter to The Lancet highlighting the potential effect on the UK’s cognitive health.

Although a solution to this problem is yet to be found, John’s pioneering work on iodine has inspired his successors to continue lobbying on this public health issue and draw politicians’ and the public’s attention to it. The importance of adequate iodine intake in pregnancy  is also recognised in the RCOG guideline on thyroid disorders and pregnancy.

Antenatal screening

In some countries, thyroid function is routinely checked in pregnancy. Some observational studies suggested that children born to mothers with low thyroid levels have reduced cognitive function. Keen to investigate this further, John established the Controlled Antenatal Thyroid Screening (CATS) programme in the early 2000s. The study aimed to determine whether giving levothyroxine to women with low thyroxine levels during pregnancy would improve their children’s cognitive function at the age of 3.

Although the results showed that this did not result in any improvement, the study inspired further research examining the effect on their children’s cognitive function at the age of 9.5. Again, the results showed no difference but did show that children of mothers who were ‘overtreated’ with levothyroxine displayed more symptoms of Attention Deficit and Hyperactivity Disorder (ADHD) and behavioural difficulties. This led researchers to conclude that mothers being treated with levothyroxine during pregnancy require close monitoring to avoid over- treatment.

The CATS study has continued to evolve and will shortly investigate whether screening thyroid function in women, and treating those with low thyroid levels, affects their children’s attainment up to school leaving age. It has also applied sophisticated brain imaging to investigate whether treatment of mothers with suboptimal thyroid function reduces the risk of their children developing neurological disorders by the age of 18.

It is thanks to John setting up this trial, and many others, that researchers have such clinically impactful data. This will continue to help them advance their understanding of thyroid disease to ensure patients receive improved treatment and care. John’s legacy will live on for many years to come.   

Watch the full webinar honouring Prof Lazarus' work 

Further information

Thyroid Eye Disease Amsterdam Declaration Implementation Group UK (TEAMeD) 

Postpartum thyroiditis 

Maternal iodine intake 

Royal College of Obstetricians and Gynaecologists; Green-top Guideline: Management of Thyroid Disorders in Pregnancy’