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Dr. Kaye Ibbertson and Iodine Deficiency in the Himalayas
The Legacy of Dr. Kaye Ibbertson.
In 2024, Our Health Journeys partnered with Saint Kentigern College in Auckland and challenged a number of students to conduct research into an aspect of the medical history of Aotearoa New Zealand. The students, ranging from Years 8-13, produced their research in written, oral, or video format and the top projects were chosen for publication to Our Health Journeys. A new project was published weekly following the completion of the project, until late October 2024.
The Legacy of Dr. Kaye Ibbertson
Doctor Henry Kaye Ibbertson, born 26th November 1926, was a New Zealand doctor and Emeritus Professor of Endocrinology (the study of hormones) at the University of Auckland. Dr. Ibbertson graduated from the University of Otago in 1951 and went on to establish the Department of Endocrinology at Auckland Hospital in the mid-1960s, where he was the head of department. Between the years of 1966 and 1972, Dr. Ibbertson travelled to Nepal three times with Sir Edmund Hillary to study the effects of iodine deficiency among the Sherpa population of the high Himalayas. This led to a programme of iodinisation that significantly improved the health of the Sherpa population, with these health benefits continuing to the present day.
Dr. Ibbertson’s study and treatment of iodine deficiency in the Himalayas
Dr. Ibbertson and his team studied the lifestyle and conditions of the Sherpa people living in isolated villages in the Khumbu region of the Nepalese Himalayas. The soil of the Himalayas is notably deficient in iodine. Therefore, foods grown in the soil and consumed by the Sherpas are not an adequate source of iodine. Iodine is vital for the production of thyroid hormones, and iodine deficiency can cause several health conditions, including miscarriage, cretinism, goitre, and hypothyroidism (an underactive thyroid).
Dr. Ibbertson observed two main iodine-related health issues amongst the Sherpa population: goitre (the enlargement of the thyroid gland) and cretinism. Large goitres may cause difficulties breathing and swallowing, as well as hoarseness and pain. Cretinism, now called congenital hypothyroidism, is a condition in which the most severely affected have a combination of intellectual disability, deaf mutism, short stature, and spasticity. Congenital hypothyroidism can be caused by a maternal iodine deficiency in the developing foetus and by early postnatal iodine deficiency.1 This meant that, in order to reduce the prevalence of congenital hypothyroidism, it was important for Dr. Ibbertson to ensure pregnant and lactating women, and young babies within the Sherpa population were consuming adequate amounts of iodine.
In a 1971 study Dr. Ibbertson found that, among the 1294 Sherpas studied, 92% had goitre and 63% had a clearly visible goitre.2 Among a subset of 475 Sherpas examined by Dr. Ibbertson himself, the incidence of congenital hypothyroidism was 5.9%, and the incidence of deaf mutism was 4.7%.2 Iodine deficiency was proven to be the cause of these issues through the measurement of urinary iodine concentrations – the mean excretion of iodide was 16.7±13.2 mcg/g creatinine across the population.2 This classified the Sherpa population as severely iodine deficient. More modern World Health Organisation (WHO) criteria (using different units for individuals) states that the optimum urinary iodine concentration is 100 μg/L or greater.
As a result of these observations, Dr. Ibbertson and his colleagues were able to effectively treat the Sherpa population with iodised oil. The success of the treatment stemmed from the prolonged activity of iodised oil which lasts for approximately a year if taken orally, or for 3-7 years if administered by intramuscular injection.2 The positive effects of this treatment soon became obvious – children born with an adequate exposure to iodine in utero and postnatally did not display any of the health problems compared to those who had experienced iodine deficiency, and many goitres drastically decreased in size (see figures 2 and 3, identified by clicking on the purple circles under the images).
The lasting impacts of Dr. Ibbertson’s work
A University of Otago study in 2009 showed the incidence of goitre amongst the Sherpa population had dropped from 92% in the 1960s to 31%. Additionally, the median urinary iodine concentration of the population was measured to be 96.5 μg/L, nearing the optimum median concentration defined by the WHO. Although some iodine deficiency was still present in the population, there were marked improvements since the 1960s which can be partially attributed to the efforts of Dr. Ibbertson and his team. In addition, the Nepalese government’s implementation of iodised salt (first established in 1973) has had a very large impact on increasing net iodine consumption. While the administration of iodised oil was phased out in 1998 in favour of salt iodisation, Dr. Ibbertson and his colleagues undoubtedly improved the lives of many people in remote Himalayan villages, especially at a time when these places had limited access to newly implemented iodised salt.
Figure 3 long-form image caption: Three brothers living in the Nepalese Himalayas that demonstrate the spectrum of iodine deficiency. One (far left) is 7 years old, has normal speech and hearing and a normally functioning thyroid gland. The brother in the middle is 18 years old and suffers from deaf mutism, intellectual disability, spasticity, and has a large goitre. The last brother on the far right is 19 years old, deaf, has a mild speech defect, normal intelligence, a normally functioning thyroid gland, and a small goitre.
Additional References
1 Ibbertson, H. K., Pearl, M., McKinnon, J., Tait, J. M., Lim, T., & Gill, M. B. (1971). Endemic Cretinism (B. S. Hetzel & P. O. D. Pharoah, Eds.; pp. 70–88 (Chapter 6)).
2 Azizi, F. (2007). IODIZED OIL: ITS ROLE IN THE MANAGEMENT OF IODINE DEFICIENCY DISORDERS (REVIEW ARTICLE). Int J Endocrinol Metab,5(2), 91–98.