I for Iodine

Date: 06/25/2011

“Medicine is a social science and politics is nothing more than medicine on a larger scale.”-- Rudolf Virchow

My study of public health in India began in All India Institute of Medical Sciences (AIIMS) in New Delhi (marked on the map). While in America, I had a serendipitous reconnection with Ritwik Pandav who was my best friend in third grade. His father, Dr. CS Pandav, is the head of the Department of Community Medicine at AIIMS and an expert on Iodine deficiency disorders (IDD). Dr. Pandav very graciously invited me to an intra-departmental symposium where I got an excellent primer on the principles and practice of community medicine and public health in India. Today I want to blog a bit about Iodine deficiency which was a big part of our discussions.

This image (courtesy Zimmermann, Jooste, and Pandav, 2008) tells the story of this little girl from western China who suffers from IDD. SHe has severe mental retardation and stunting. Some common facial features you can see here are the widely spaced eyes, saddle nose deformity, immaturely developed jaw bones, and thickened and dried skin and hair. I keep her face in my head when I think of Iodine deficiency disorder.

Iodine deficiency has been a much researched topic at AIIMS since the work of V. Ramalingaswami, a giant in the field, in the 1970s. Iodine deficiency in children can begin while they’re still in the uterus. Iodine is necessary for the production of thyroxine in the thyroid gland. Thyroxine is necessary for both the development of the brain and the body. It is important in the formation of myelin sheaths, which insulate the brain cells, in the brain and the spinal cord as well as the formation of connections between brain cells (synapsis) in foetuses and children. Severe iodine deficiency, unsurprisingly, results in mental deficiencies, physical stunting, and spasticity. Indeed, there is a 13 point difference in the IQ of children in Iodine deficient and Iodine sufficient areas of the country! This, coupled with physical stunting, leads to a very significant difference in income.

Fortunately, these deficiencies are reversible in childhood (to a certain degree) by correcting the iodine deficiency. In fact, the Disease Control Priorities Project (DCPP) suggests that the iodination of salt is an excellent investment. It involves an investment of 5 cents per child per year. When making policies in public health, we consider a concept called Disability-Adjusted-Life-Years (DALY) which is a measure of the the number of years of life lost through the morbidity and mortality of disease. If you value each DALY at $1000, salt iodization gives you a 30:1 benefit: cost ratio-- a smart idea (see the DCPP table below).

Ensuring the adequate iodine intake of the population involves frequent testing. T3, T4, and TSH tests are not sensitive tests. Urinary iodine concentrations are therefore used to assess iodine sufficiency. A concentration above 100 ug/L , which indicates an iodine intake of 150 ug per day, is considered sufficient. Pregnant women should consume about 250 ug of Iodine everyday (150-249 ug/L of Iodine in urine). Excessive consumption of Iodine yields a urinary output of 300 ug/L (500ug/L in pregnant women). Another direct test for severe Iodine deficiency is looking for goitre, an increase in the size of the thyroid gland.

This image (courtesy zimmermann, Jooste, and Pandav, 2008) shows an incredibly large goitre. The requirement for goitre to be diagnosed, ordinarliy, is that each lobe of the thyroid gland in the neck is larger than the size of the distal phalanx of the thumb (the tip-most bone of the thumb).

There was also some discussion of the salt iodination programme in India. Apparently, the government of India had placed a ban on the sale of non-iodized salt in the country in 1997. However, elements in the medical community raised concerns regarding the side effects of Iodine overdose and the government ended the ban in 2000. Consequently, the fraction of households using iodized salt fell by 12% (Zimmermann, Jooste, and Pandav, 2008) Fortunately, researchers-- spearheaded by those at AIIMS-- proved that the horrors of IDD eclipsed the possibility of over-iodination. As a result, the government reinstated the ban in 2005. Considering the devastation Iodine deficiency wreaks on human capital through its effects on physique and cognition, I find it deeply disturbing that more than 17 million south asian children are born in houeholds that are not protected by iodized salt every year.

Amartya Sen describes poverty as an individual’s incapability to realize his or her full potential as a human being (as cited in Banerjee and Duflo, 2011). If we accept this description, correcting iodine deficiency disorders is a key step in reducing the poverty of our world. Zimmermann, Jooste, and Pandav underline the importance of educating political leaders and forming public coalitions to address this issue. This responsibility falls largely on the shoulders of doctors who are, after all, public intellectuals. The more I proceed in my medical education, the more I feel that our battle is not so much against disease as it is against poverty.

"Only in India" moments:

I was walking in the street when I saw a scooter hurtling towards me. I leapt aside with a yell to avoid being mown like a helpless lawn.

Pranay: Dekho Dekho! (Watch out!)

Scoter driver: Arrey, side hato na! (Why the hell don’t you get out of the way instead of yelling?)

Ah, I love my country.

Sources:

1. Zimmermann, MB, Jooste, PL, and Pandav, CS. Iodine deficiency disorders. The Lancet: 372 (2008)
2. Alderman, H. Stimulating economic growth through improved nutrition. Disease Control Priorities Project (dcp2.org) (2008)
3. Banerjee, AV and Duflo E. Poor Economics. Random House India. 2011