As a medical student, I’d seen plenty of photographs of enlarged thyroid glands. Necks that looked like a grapefruit was growing under the skin above the collar.

They featured prominently in textbooks, usually accompanied by discussions about iodine deficiency and thyroid disease.

I never expected to see one like that in person.

Then I worked in Tasmania.

Suddenly I found myself encountering people with goitres and couldn’t understand why.

A local doctor explained that for generations, parts of Tasmania had struggled with iodine deficiency. The problem was so significant that public health measures were introduced to combat it, including adding iodine to milk supplies and later fortifying foods.

I’ve met people in their 80s who, as children, were given iodine tablets to add to their school milk, one of whom dissolved his in the ink well each day to avoid having to swallow it.

At the time, I thought it was an interesting piece of medical history.

Years later, I realised it was much more than that.

While researching one branch of my family tree, I stumbled across a mystery.

My great, great grandfather, Nicholas Flynn and his wife arrived in Australia and moved to Coleraine in Victoria. They had ten children. That wasn’t unusual.
What surprised me was that only two of those ten children went on to have children of their own. The daughters died either spinsters or married without children.

The deeper I dug, the more confronting the story became.

The girls who married lost children born years apart in infancy. I suspect there were multiple miscarriages in between.

At least three of the ten children had developmental disabilities requiring lifelong care.

The spinster sisters never married and lived with the disabled siblings, presumably as life-long carers.

Delving deeper, I wondered whether some of the same nutritional deficiencies that once affected entire communities might have influenced the course of my own family’s story.

Then a word written on the death certificates of two of Nicholas’ infant grandchildren pointed to a reason. “Cretinism,” a term no longer used in medicine.

Its cause? Iodine deficiency.

Iodine deficiency was once incredibly common in many parts of the world, including Australia, particularly in areas with little iodine in the soil.

The thyroid gland requires iodine to produce thyroid hormones, which are essential for growth, metabolism and brain development.

When iodine is lacking, the thyroid tries to compensate by enlarging.

For adults, iodine deficiency can cause an underactive thyroid leading to fatigue, weight gain, cold intolerance and thyroid enlargement.

For pregnant women and their babies, the consequences can be far more serious.

Severe iodine deficiency during pregnancy has been associated with miscarriage, stillbirth, impaired growth and intellectual disability in children. In the past, some affected children developed severe physical and intellectual impairment, then known as cretinism.

Today, most Australians rarely think about iodine.

That’s partly because public health measures have been so successful.

Iodine was added to foods. Deficiencies were recognised and treated. Pregnant women were encouraged to ensure adequate intake. What was once a major public health problem largely faded from public consciousness.

And that’s the paradox of successful public health.

When it works, people stop noticing.

We celebrate dramatic medical breakthroughs. The surgeon who performs a life-saving operation. The new cancer treatment. The patient who survives against the odds.

Far less attention is paid to the quiet interventions that prevent disease from occurring in the first place.

Clean water.

Vaccination programs.

Food safety regulations.

Folate supplementation.

Iodine fortification.

Yet these measures have saved countless lives and prevented enormous suffering.

Historical records rarely provide definitive answers, but Coleraine was associated with low levels of iodine in the soil, just as in Tasmania.

Looking back at my family history, I can’t say with certainty which illnesses or deficiencies influenced individual lives, but iodine is one likely culprit.

What I can say is that researching those generations gave me a new appreciation for how much modern public health has changed our lives.

Many of the tragedies that were once accepted as part of everyday life are now rare.

Not because we became luckier but because we learned more.

Sometimes the greatest advances in medicine aren’t the ones that make headlines.

They’re as simple as adding a tiny amount of iodine to the food supply and quietly changing the course of generations.

Dr Kathryn Fox is an Australian medical doctor and bestselling crime writer, best known for her forensic thrillers featuring pathologist Dr Anya Crichton. Drawing on her medical expertise, she crafts gripping, authentic crime fiction and is also a passionate advocate for forensic medicine education and public engagement. Her columns appear twice weekly.