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Hypothyroidism preceding hyperthyroidism in a patient with continuously positive thyroid stimulating antibody
H Yamasaki1, K Takeda, Y Nakauchi
1Second Department of Internal Medicine, Kochi Medical School, Nankoku.
Internal Medicine (Tokyo, Japan)
|April 1, 1995
Summary
Primary hypothyroidism with positive thyroid-stimulating antibody (TSAb) may indicate a future risk of developing hyperthyroidism. Continuous TSAb positivity is a key indicator in this thyroid disorder progression.
Area of Science:
- Endocrinology
- Immunology
- Thyroidology
Background:
- Thyroid disorders encompass a spectrum of conditions, including hypothyroidism and hyperthyroidism.
- Thyroid-stimulating antibody (TSAb) is a key autoantibody implicated in Graves' disease, a common cause of hyperthyroidism.
Observation:
- A 62-year-old woman presented with initial hypothyroidism followed by the development of hyperthyroidism.
- Throughout this transition, thyroid-stimulating antibody (TSAb) remained consistently positive.
- Thyroid-stimulating hormone (TSH) levels initially showed a slight elevation, with free T4 levels being low during the hypothyroid phase.
Findings:
- Levothyroxine (l-T4) supplementation for hypothyroidism preceded the onset of hyperthyroidism.
- The patient exhibited increased radioactive iodine uptake during the hyperthyroid phase.
- TSAb was continuously positive, whereas TSH-binding inhibitor immunoglobulin (TBII) was only transiently elevated during hypothyroidism, and thyroid stimulation-blocking antibody (TSBAb) was undetectable.
Implications:
- The continuous presence of TSAb during a hypothyroid phase may predict the subsequent development of hyperthyroidism.
- This case highlights the dynamic nature of autoimmune thyroid disease and the importance of monitoring antibody levels.
- Understanding antibody profiles can aid in predicting disease progression and managing thyroid dysfunction effectively.