Six months of persistent fatigue, increased hair loss, unexplained weight gain, and consistently restless sleep. For many Brazilian women, these symptoms are often dismissed as stress, early menopause, or simply the effects of aging. But, in many cases, the root cause lies elsewhere: the thyroid.
The butterfly-shaped gland located at the base of the neck is responsible for producing the hormones T3 and T4, which regulate metabolism, heart rate, body temperature, menstrual cycles, fertility, memory, and mood.
When the thyroid malfunctions, nearly every system in the body can be affected. Hypothyroidism, a condition where the thyroid produces insufficient hormones, affects an estimated 18 million people in Brazil, according to the Brazilian Society of Endocrinology and Metabolism.
The number is concerning, but even more so is the fact that a significant proportion of those affected are unaware they have the condition. This is particularly true in the North and Northeast regions of Brazil, where access to specialized medical services is limited.
A Condition Masked by Everyday Symptoms
The challenge with hypothyroidism isn’t just its prevalence, but the difficulty in recognizing it. The symptoms are often diffuse and frequently mistaken for other conditions.
Fatigue, hair loss, dry skin, constipation, a constant feeling of cold, unexplained weight gain, sleepiness, mood swings, and difficulty concentrating are common signs. However, each symptom individually can be attributed to numerous other causes, leading to delayed diagnosis.
Research conducted in partnership with the Minds4Health Institute showed that in 65% of cases, a hypothyroidism diagnosis occurred during a routine general check-up.
Only 30% of patients sought medical attention due to a specific symptom. Which means that for the majority of people with the condition, the path to treatment relies on the chance of a blood test ordered for an unrelated reason.
The primary cause of hypothyroidism in adults is Hashimoto’s thyroiditis, an autoimmune condition responsible for approximately 80% of cases. In this condition, the immune system attacks the thyroid gland, progressively impairing its ability to produce hormones. The disease affects women 10 to 15 times more often than men, with a higher incidence after age 40.
Thyroid Nodules: What the Data Shows
Hypothyroidism isn’t the only issue the thyroid can present. Thyroid nodules are extremely common; the Brazilian Society of Endocrinology and Metabolism estimates that 60% of the Brazilian population will develop them at some point in their lives.
Most of these nodules are benign. Clinical research indicates that only 5% of all thyroid nodules are malignant. Identifying those 5% in a timely manner is crucial, requiring regular medical follow-up and imaging tests like ultrasound, and, when indicated, a fine needle aspiration biopsy.
Thyroid cancer has shown an increasing incidence in Brazil. Between 2000 and 2024, the incidence grew steadily, according to a review published in a Brazilian scientific journal based on data from INCA and DATASUS. For each year from 2020-2022, approximately 11,950 new cases of thyroid cancer were estimated in women across the country.
Despite the rising numbers, the prognosis, when diagnosed early, is largely favorable. The overall survival rate for the most common type, papillary carcinoma, is estimated at 95%. Again, early detection is key.
Regional Disparities in Access to Care
Regional inequalities in the diagnosis of thyroid diseases are well-documented. Studies indicate that the South and Southeast regions of Brazil have higher reported incidence rates due to greater availability of diagnostic centers, ultrasounds, and endocrinologists per capita. In the North and Northeast, structural limitations lead to underreporting.
This doesn’t mean cases are less frequent in those regions, but rather that a portion of them go undiagnosed. For someone living in Alagoas or another state in the Northeast experiencing symptoms potentially related to the thyroid, the distance to an endocrinologist can be a decisive factor in receiving treatment or living with a silently progressing condition.
Fortunately, diagnosing hypothyroidism is simple and inexpensive. A blood test measuring TSH and free T4 levels is sufficient to identify the abnormality. However, as experts from the Department of Thyroid at SBEM point out, a significant proportion of those with the condition are simply unaware they need this test.
When to Seek a Specialized Endocrinologist
Not every thyroid abnormality requires a specialist. However, there are situations where the evaluation of an endocrinologist specializing in thyroid disorders can directly impact treatment outcomes.
The first is when a diagnosis has already been made, but treatment isn’t producing the expected results. Hypothyroidism is treated with levothyroxine replacement, but adjusting the correct dosage requires regular monitoring and, in some cases, a more in-depth evaluation of factors interfering with medication absorption. Approximately 25% of diagnosed patients don’t adhere to treatment properly, according to data from the Minds4Health Institute.
The second situation is when nodules are identified on an imaging exam. In these cases, the endocrinologist determines the follow-up protocol, decides if a biopsy is necessary, and assesses the risk of malignancy based on specific criteria, such as size, ultrasound characteristics, and patient history.
The third is when symptoms persist despite a lack of a definitive diagnosis. Hyperthyroidism, subclinical hypothyroidism, Graves’ disease, and Hashimoto’s thyroiditis have distinct clinical presentations and can coexist with other endocrine conditions, such as diabetes, polycystic ovary syndrome, and pituitary disorders. Specialized evaluation reduces the risk of misdiagnosis.
Treatment and What to Expect
For clinical hypothyroidism, treatment is medicinal and ongoing. Levothyroxine is a synthetic thyroid hormone that replaces what the gland is no longer producing. The goal is to normalize TSH and free T4 levels and, in doing so, reverse the symptoms.
The adjustment process can grab weeks. The initial dose is calibrated by the endocrinologist and reevaluated through periodic blood tests. In pregnant women, control is even more rigorous, as untreated hypothyroidism increases the risk of obstetric complications and affects the neurological development of the baby.
For hyperthyroidism, options include medications that reduce hormone production, radioactive iodine, or, in specific cases, surgical intervention. The choice depends on the cause, the severity of symptoms, and the patient’s profile.
In any case, treatment doesn’t finish with a prescription. The thyroid is a dynamic gland, subject to changes throughout life. Factors such as pregnancy, menopause, the use of other medications, and changes in body weight can alter a patient’s hormonal needs. This highlights the importance of regular follow-up with a specialist.
What Patients Can Do Before Their Appointment
Accurately recording symptoms is very helpful during a consultation. Noting when fatigue began, if there has been weight change without dietary changes, if there is any alteration in the menstrual cycle, if hair loss has worsened, and if there is a family history of thyroid disease are all pieces of information the doctor will ask for and that make a difference in diagnosis.
According to Dr. Camila Farias, an endocrinologist practicing in Goiânia, a self-examination of the thyroid can also be performed at home. SBEM recommends that women, especially those over 40, perform self-exams regularly: with a mirror and head tilted slightly back, observe the base of the neck even as swallowing saliva. Any increase in volume or swelling in the area warrants medical evaluation.
Previous laboratory tests, especially those including TSH and free T4, should also be brought to the appointment so the doctor can assess the evolution of values over time. When nodules have been previously identified, bringing the ultrasound report facilitates the specialist’s work.
Early Diagnosis Improves Prognosis
The thyroid rarely causes death directly. But when its dysfunctions go undiagnosed for years, the effects accumulate. Untreated hypothyroidism increases the risk of coronary artery disease, anemia, neurological changes, and complications in pregnancy. Thyroid cancer, diagnosed late, reduces the chances of a favorable prognosis.
The key takeaway is this: diagnosing hypothyroidism is inexpensive and done with a simple blood test. Treatment, when indicated, is accessible. What’s often lacking is the patient seeking evaluation from a specialist before years of symptoms diminish quality of life without a cause being identified.
For those recognizing symptoms that may be related to the thyroid, the first step is to seek medical evaluation. The sooner a diagnosis is made, the simpler the path to appropriate treatment tends to be.
