Quick Refresher

• What is the thyroid gland and what does it do
• Hypothyroidism (underactive, low thyroid)
• Hyperthyroidism (over-active, high thyroid)
• Autoimmune thyroid disease
• Congenital hypothyroidism
• Acquired hypothyroidism

Question 1: I’d never heard of thyroid problems in children until my child was diagnosed with hypothyroidism. Are thyroid problems increasing in children?

Answer: It depends on the specific thyroid problem to which you are referring.

Acquired hypothyroidism is a maybe. Autoimmune thyroid disease also known as Hashimoto disease is the leading cause of acquired hypothyroidism in adults. Research studies have definitely shown a worldwide increase of Hashimoto disease in adults, and there is likely also an increase in children.

The most scientifically validated reason for the worldwide increase in Hashimoto disease is improved iodine intake. Iodine is a very important mineral that is necessary for thyroid hormone production. Lack of the mineral remains a common cause in certain third-world areas of the world for a specific form of hypothyroidism termed endemic goiter. For some reason, however, the improved supplementing of iodine may be a culprit in triggering autoimmune thyroid disease in adults.

Congenital hypothyroidism is a yes. Researchers are trying to understand the observed increase in incidence of congenital hypothyroidism. The historic quoted incidence is roughly 1 in every 4000 new births. Current trends are showing higher incidence at roughly 1 in every 2500 births. There are a number of different theories about why this is seen. One factor is the increased number of surviving premature babies. Many of these babies have a thyroid problem termed transient hypothyroidism during their early life requiring treatment with thyroid hormone and are counted in the same category as congenital hypothyroidism .

An increase in the Hispanic population is another factor theorized to account for the change. There is a higher incidence overall in Hispanics of congenital hypothyroidism which may be influencing the incidence numbers.

Radioactive iodine exposure during pregnancy has definite negative impact on fetal thyroid activity, and exposure must be avoided. Concern was sparked in 2012 with a controversial study published suggesting a link between the Fukushima nuclear disaster and a spike in the number of cases of congenital hypothyroidism seen in U.S. Pacific Coast states.

Question 2: Why did my child develop Hashimoto disease?

Answer: Medical science doesn’t know the precise reason(s) for autoimmune thyroid disease which includes Hashimoto thyroiditis. We believe that there are factors both genetic and environmental involved.

Research suggests that genetics underlies about 70 percent of the susceptibility in Hashimoto disease which is why a family history of thyroid problems is often seen in children with Hashimoto disease. Of the various genes identified with risk for Hashimoto disease, the HLA-DR gene association is best known. The gene location is known most widely for its importance in organ transplant

Environmental triggers are the great unknown not only in Hashimoto disease but also in many other autoimmune conditions. Infection triggers seem to be the most likely candidates in this process. Hepatitis C infection and Rubella (German measles) are two infections with known links to autoimmune thyroid disease. In addition to known harmful infections, possible impact of disturbance in beneficial intestinal bacteria as a trigger in autoimmune thyroid disease as well as other autoimmune conditions is being investigated.

Smoking in adults has been linked to increased risk for autoimmune thyroid disease and is another of the many reasons to avoid smoking. More controversial theories include environmental pollutants role in autoimmune thyroid disease. PCBs and PBDEs have been linked to increased risk in some research studies mainly in animals.

Radiation exposure is a known risk in many thyroid problems in both adults and children. Childhood thyroid cancer rates increased drastically after the Chernobyl disaster. Both autoimmune thyroid disease and thyroid cancer risk are increased in cancer survivors who received radiation treatment. Fortunately, routine medical radiation exposure doesn’t appear to be linked to higher risk of thyroid damage.

Question 3: Can diet help prevent or improve thyroid problems?

Answer: Yes, to some extent

The mineral iodine is essential for proper thyroid hormone production. Fortunately, in the U.S., lack of iodine is extremely uncommon. Seafood and dairy are both good sources of iodine, and iodine is added to salt as well. Risk of iodine deficiency is very low in in children who eat a healthy, balanced diet and have no digestive problems.

Goitrogens are naturally occurring chemicals in certain vegetables such as cauliflower that can interfere with function of the thyroid. Overall, the health benefits of goitrogen-containing vegetables probably outweigh the risks to the thyroid when eaten in a balanced manner.

Question 4: What can I do to help others in my family or family friends be more aware of thyroid problems?

Answer: Awareness is the key.

Awareness of symptoms of thyroid disease is important when there is a family history of thyroid problems. An exam of the thyroid and a blood testing can uncover thyroid problems. Sharing the story of your child’s medical history with concerned friends can also help.

I hope these answers help those of you who have a child diagnosed with a thyroid issue. If you still have questions or need more help, please contact your primary care doctor or the Cook Children’s Endocrinology division.

Chemotherapy and radiation treatments used to treat cancers often damage several endocrine systems in the body. The diagnosis of endocrine problems may occur at any stage in a child’s cancer treatment, and it’s particularly important to search for late effects appearing years after cancer treatment. Studies have shown the growing recognition of these late effects of childhood cancer treatment such as obesity and metabolic syndrome. Damage from the silent presence of these problems may take years to appear.

I created the clinic because I believe that endocrine evaluation and care has a lot to offer childhood cancer survivors.  I’m not alone as many endocrinologist are recognizing their role in the care of survivors. A report published last month detailing information learned from a large scale Scandinavian study of childhood cancer survivors further emphasized the important role that endocrinology should play in the care of survivors.

The study showed that children who survive cancer have a five times greater risk of developing an endocrine disorder late in life. The risk was highest in young survivors, but continued on into adulthood. Even by the time a patient was 60 years old, they had a 42 percent chance to develop an endocrine disorder.

Survivors of leukemia, central nervous system tumors and Hodgkin’s lymphoma were at the greatest risk.

Three primary endocrine problems were seen in the study.

• Hypopituitarism
• Hypothyroidism
• Gonad (ovaries/testes) failure

The Childhood Cancer Survivor Study (CCSS), a multi-center study sponsored by the National Cancer Institute has been ongoing since 1993 in the United States and provides valuable information comparable to the recent information from Scandinavia. The detailed information and guidelines from the CCSS prove very helpful in my care of young adults who have survived cancer.

I understand that many survivors and their families desire to put the stormy period of cancer treatment behind them and not to think about, but it’s important to remain engaged in health care and follow-up. I have provided endocrine support for Cook Children’s Life After Cancer Program (LACP) and Neuro-oncology program  now for five years and have found this role very rewarding in improving the quality of life of childhood cancer survivors. I look forward now to further expanding that role.