Thyroid Disorders: Overview, Diagnosis, Monitoring, and Testing
Thyroid hormone homeostasis is essential for normal growth and development. In an intricate negative feedback mechanism, thyroid hormone concentrations are maintained within relatively narrow limits to ensure optimal health. Disruption of the dynamics within the hypothalamic-pituitary-thyroid axis can disrupt normal thyroid function. Diabetes, especially type 1 diabetes, can put a person at a higher risk for developing thyroid disease.
Thyroid Disorders
Hypothyroidism, an underactive thyroid, is one of the most undiagnosed, misdiagnosed, and unrecognized health problems in the world. Hypothyroidism—is insufficient production of thyroid hormone—typically presents with low levels of T4. It is the most common thyroid dysfunction. Dysfunction can occur due to problems in the thyroid itself—that is, primary disease—or it may be due to problems in the pituitary or hypothalamus known as central hypothyroid disease.
Hashimoto’s thyroiditis is the most common form of autoimmune thyroiditis. The immune system that protects the body from invading infections can mistake thyroid gland cells and their enzymes for invaders and attack them, leaving too few thyroid cells and enzymes left to make sufficient thyroid hormone. This is more common in women than men. Autoimmune thyroiditis can begin suddenly, or it can develop slowly over years. Hypothyroidism risk factors include gender, age, prior history of thyroid disease or treatment, personal history of autoimmune disease, and family history of thyroid disease.
Hyperthyroidism results from overproduction of the thyroid hormones T4 or T3. The endogenous condition occurs relatively infrequently, while exogenous hyperthyroidism states may be triggered by excess medication.1 Excess thyroid hormones affect cardiac performance, the renal and skeletal systems, liver function, and the female reproductive system.
Graves’ disease is estimated to affect 2–3% of the general population. One of the most common forms of hyperthyroidism, Graves’ disease is an autoimmune disorder characterized by the presence of stimulating TSH receptor autoantibodies. TSH receptor autoantibodies mimic the activity of TSH, leading to an elevated production of thyroid hormone.2 Left untreated, Graves’ disease can lead to miscarriage, birth defects, and thyroid eye disease and can be life-threatening.
Thyroid cancer affects an estimated >500,000 people worldwide.3 The incidence of thyroid cancer has increased dramatically during the past three decades and is now the fastest growing cancer in women.4 There are four main types of thyroid cancer:5
- Papillary thyroid cancer is the most common type, accounting for about 70–80% of all thyroid cancers.5 It can occur at any age, tends to grow slowly, and often spreads to lymph nodes in the neck. Papillary cancer has a generally excellent outlook, even if there is spread to the lymph nodes.
- Follicular thyroid cancer makes up about 10–15% of all thyroid cancers in the United States. Follicular cancer can spread through the blood to distant organs, particularly the lungs and bones.
- Medullary thyroid cancer (MTC) accounts for approximately 2% of all thyroid cancers. Approximately 25% of MTC runs in families and is associated with other endocrine tumors.
- Anaplastic thyroid cancer is the most advanced and aggressive thyroid cancer and the least likely to respond to treatment. Anaplastic thyroid cancer is very rare, found in less than 2% of patients with thyroid cancer.
The survival rate for thyroid cancer depends on many factors, but the most important is how early the nodule is identified. Early detection increases the chance that the thyroid tumor remains localized, which means it hasn’t spread from the thyroid itself.6
Diagnosing and Monitoring the Condition
A Patient Assessment Stratification for Thyroid Dysfunction: Click the image to see the detailed diagram.
Hypothyroidism
Patient assessment, beginning with the measurement of TSH, is the best indicator of hypothyroidism.7 Analysis of anti-TPO antibodies contributes information to the investigation of subclinical hypothyroidism.8
Hyperthyroidism
A low TSH with an elevated FT4 usually indicates hyperthyroidism.9 Sometimes T4 is normal but T3 is high, so measuring both T4 and T3 levels can be useful in diagnosing hyperthyroidism.9
Thyroid Cancer
Blood tests are important for thyroid cancer patients. Most patients who have had a thyroidectomy for cancer require thyroid hormone replacement with levothyroxine after the thyroid is removed.
Another important blood test is measurement of thyroglobulin (Tg). Thyroglobulin is a protein produced by normal thyroid tissue and differentiated thyroid cancer cells. The Tg test aids in the monitoring of patients who have undergone thyroidectomy to evaluate treatment and outcomes, including thyroid cancer recurrence and metastasis and radioactive iodine ablation, when the thyroglobulin levels usually become very low or undetectable. If the level is low and then starts to rise, it is concerning for possible cancer recurrence. The presence of thyroglobulin antibodies (TgAb) should be measured along with Tg testing to improve interpretation. Calcitonin shows good sensitivity for MTC.5
Siemens Healthineers comprehensive thyroid menu allows clinicians to diagnose, confirm, and monitor a wide range of thyroid disorders.
*Not available for sale in the U.S. Future availability cannot be guaranteed.
May 25 Is World Thyroid Day
Each May, Siemens Healthineers works to raise awareness about thyroid disorders which often are life-long conditions that can be managed by monitoring thyroid levels. We are committed to the care of patients by raising awareness through a variety of resources to help keep you informed of the latest topics in thyroid testing.
Infographic: Thyroid Disease
Infographic: Thyroid disease
Webinar: The transition from the Atellica IM aTG assay to the Atellica IM aTgII assay
Anti-thyroglobulin (aTG) measurements are used as an aid in the diagnosis of Hashimoto’s and Graves’ diseases, which are autoimmune diseases affecting the thyroid gland. Dr. Josep M. Auge Fradera, an expert in thyroid disorders, reviews the role of anti-thyroglobulin antibodies and uses clinical case findings for examples of the value of testing. He also presents his analysis comparing the existing Atellica® Anti-thyroglobulin (aTg) assay with the new Atellica Anti-thyroglobulin (aTgII) assay and highlights the clinical benefits of the aTgII assay.
Speaker:
Josep M. Auge Fradera, MD, PhD
Biochemistry and Molecular Genetic Department
Hospital Clinic-Barcelona
Webinar: Understanding Thyroid Disorders in Pregnancy
Understanding the role that thyroid disfunction plays in pregnancy is critical in light of the natural fluctuation of hormones and how this affects the mother and baby. Dr. Monet Sayegh, M.D reviews thyroid disease in pregnancy, the need for trimester-specific reference ranges for thyroid function tests, and treatment options for thyroid dysfunction in pregnant vs. non-pregnant women.
Speaker:
Dr. Monet Sayegh
Senior Clinical Consultant
Siemens Healthineers
TSI Literature Compendium: Third-party articles comparing the diagnostic value of the IMMULITE 2000 TSI assay (a bridge assay) to TRAb assays
Diagnosing Graves’ disease
Predicting the progression of autoimmune disorders – insights into Graves’ disease
*Not available for sale in the U.S. Not commercially available. Future availability cannot be guaranteed.
Canaris GI, Manowitz NR, Mayor G, Ridgeway BC. The Colorado Thyroid Disease Prevalence Study. Arch Intern Med. 2000;160: 526-34.
Klee GG, Hay ID. Biochemical testing of thyroid function. Endocrinol Metab Clin North Am.1997;26:763-75.
Sossein G, Tuttle RM, Baskin HJ, Fish LJ, Singer PA, McDermott MT. Consensus statement: Subclinical thyroid dysfunction: a joint statement on management from the American Association of Clinical Endocrinologists, the American Thyroid Association, and the Endocrine Society. J Clin Endocrinol Metab. 2005;90(1):581-5.