Researchers studied nearly 4,000 Americans to understand if heart and metabolism health is linked to how well the thyroid works. The thyroid is a small gland in your neck that controls many body functions. Scientists found that people with higher cardiometabolic scores (a measure of heart and metabolic health) tended to have higher levels of certain thyroid hormones. While this connection is interesting, the researchers say we need more studies to understand if checking thyroid function could help predict heart health problems.

The Quick Take

  • What they studied: Whether a person’s heart and metabolism health score (called cardiometabolic index) is connected to how well their thyroid gland works
  • Who participated: 3,963 Americans of various ages (average age 50) who participated in a national health survey between 2007 and 2012. The group included men and women with different backgrounds, weights, and health histories
  • Key finding: People with higher cardiometabolic scores had higher levels of thyroid hormones. Specifically, for every one-point increase in the cardiometabolic score, thyroid hormone levels increased measurably, suggesting these two body systems may be connected
  • What it means for you: This research suggests your heart health and thyroid function may be related, but it’s too early to use thyroid tests to predict heart problems. Talk to your doctor about maintaining both heart and thyroid health through regular exercise, healthy eating, and routine check-ups

The Research Details

Scientists used information from a large national health survey called NHANES that tracked Americans’ health from 2007 to 2012. They looked at data from nearly 4,000 people and measured their cardiometabolic index (a score based on factors like waist size, blood pressure, and cholesterol) and their thyroid hormone levels. The researchers divided people into four groups based on their cardiometabolic scores and compared thyroid function across these groups. They used statistical methods to look for connections between the two measurements while accounting for other factors that might affect results, like age, gender, smoking, and existing health conditions.

This type of study is useful for spotting potential connections between different body systems in large populations. By studying real-world health data from thousands of people, researchers can identify patterns that might not be obvious in smaller studies. However, this approach shows associations (things that happen together) rather than proving one thing causes another, which is why follow-up studies are important.

The study used data from a well-respected national health survey, which is a strength. The researchers looked at a large number of people and adjusted their analysis for many factors that could affect results. However, because this is a snapshot study (cross-sectional), it only shows what was true at one point in time and cannot prove that cardiometabolic health causes thyroid changes. The findings were stronger in some groups (men, younger people, those without high blood pressure) than others, suggesting the connection may not be universal.

What the Results Show

The main finding was that cardiometabolic index and thyroid function are positively associated, meaning they tend to increase together. When researchers looked at two specific thyroid hormones called TT3 and FT3, they found clear connections to cardiometabolic scores. For every one-point increase in the cardiometabolic index, TT3 levels increased by 0.737 ng/dl and FT3 levels increased by 0.011 pg/ml. These increases were statistically significant, meaning they were unlikely to happen by chance. The relationship held true even after researchers accounted for other factors like age, gender, smoking status, and existing health conditions. People with the highest cardiometabolic scores had noticeably higher thyroid hormone levels compared to those with the lowest scores.

When researchers looked at different groups of people separately, they found that the connection between cardiometabolic health and thyroid function was stronger in some groups than others. The relationship was more pronounced in men than women, in younger people compared to older adults, in people with high blood pressure, and in people who smoked. This suggests that age, gender, and other health conditions may influence how the thyroid responds to changes in cardiometabolic health.

This research adds to growing evidence that different body systems are interconnected. Previous studies have shown that metabolic health affects many hormones and body functions, but the specific connection between cardiometabolic health and thyroid function hasn’t been thoroughly studied in large U.S. populations. This study fills that gap by providing data from a nationally representative sample, though researchers note that more studies are needed to confirm these findings in other populations.

This study has several important limitations. First, it’s a snapshot in time, so we can’t tell if cardiometabolic health changes cause thyroid changes or if something else causes both. Second, the study only included data from 2007-2012, so results may not reflect current health patterns. Third, the connection was stronger in some groups (men, younger people) than others, so findings may not apply equally to everyone. Finally, the study measured thyroid hormones but didn’t assess actual thyroid disease, so we don’t know if these hormone changes have real health effects.

The Bottom Line

Based on this research, focus on maintaining good heart and metabolic health through regular physical activity, a balanced diet, and maintaining a healthy weight. These habits support both heart health and thyroid function. If you have concerns about your thyroid or heart health, talk to your doctor about appropriate screening. This research suggests these systems are connected, but it’s not yet clear how to use this information for prevention or treatment. Confidence level: Moderate (this is one study showing association, not proof of cause-and-effect).

This research is relevant to anyone interested in understanding how different body systems work together. It’s particularly interesting for people with heart disease risk factors, metabolic syndrome, or thyroid concerns. However, this study doesn’t change current medical recommendations for thyroid or heart health screening. People should continue following their doctor’s advice about health check-ups.

If you make lifestyle changes to improve heart and metabolic health, you might see improvements in blood pressure and cholesterol within weeks to months. Thyroid hormone levels may adjust more slowly. Significant changes typically take 3-6 months of consistent effort. Talk to your doctor about realistic timelines for your specific situation.

Want to Apply This Research?

  • Track your waist circumference, blood pressure, and cholesterol levels monthly, as these are key components of cardiometabolic health. Also note any thyroid-related symptoms like fatigue, weight changes, or temperature sensitivity to share with your doctor
  • Use the app to set reminders for daily 30-minute walks or other moderate exercise, as physical activity improves both heart health and metabolic function. Log your meals to maintain a balanced diet that supports both systems
  • Create a quarterly health dashboard showing trends in cardiometabolic markers (waist size, blood pressure, cholesterol) alongside any thyroid-related symptoms or lab results from your doctor. This helps you and your healthcare provider see the bigger picture of your metabolic health over time

This research shows an association between cardiometabolic health and thyroid function but does not prove one causes the other. These findings are not a substitute for medical advice. If you have concerns about your thyroid or heart health, consult with your healthcare provider. Do not change any medications or health treatments based on this information without talking to your doctor first. This study was conducted on U.S. data from 2007-2012 and may not apply to all populations or current conditions.