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Macro-TSH: An Uncommon Explanation for Persistent TSH Elevation That Thyroidologists Have to Keep in Mind
Isabella Chiardi1,2, Mario Rotondi3,4, Marco Cantù5
1Clinic for Endocrinology and Diabetology, Lugano Regional Hospital, Ente Ospedaliero Cantonale, 6500 Bellinzona, Switzerland.
Journal of Personalized Medicine
|October 27, 2023
Summary
Macro-thyroid-stimulating hormone (macro-TSH) is a rare cause of elevated TSH levels with normal thyroid hormones. Diagnosis requires specific laboratory techniques like PEG precipitation to identify this TSH variant.
Area of Science:
- Endocrinology
- Clinical Chemistry
Background:
- Thyroid-stimulating hormone (TSH) is a key regulator of thyroid function.
- Elevated TSH with normal thyroid hormones can indicate laboratory interference or rare conditions.
- Macro-TSH is an infrequent cause of such discrepancies.
Observation:
- A 69-year-old patient presented with persistently high TSH (30-50 mIU/L).
- Thyroid hormones and ultrasound were normal, with no pituitary abnormalities.
- Initial investigations ruled out common causes for elevated TSH.
Findings:
- Polyethylene glycol (PEG) precipitation identified macro-TSH.
- Chromatography confirmed the presence of macro-TSH.
- This macro-TSH variant was the cause of the unexplained TSH elevation.
Implications:
- Highlights the importance of considering macro-TSH in unexplained TSH elevations.
- Suggests specific diagnostic approaches for TSH measurement interferences.
- Enhances understanding of thyroid function anomalies and diagnostic challenges.
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