Nuklearmedizin 2020; 59(01): 35-37
DOI: 10.1055/a-1086-0393
Case Report
© Georg Thieme Verlag KG Stuttgart · New York

Calcitonin Screening – Consideration of Heterophilic Antibody Interference in a Case of Obscure Hypercalcitoninemia

Calcitonin-Screening – Heterophile Antikörperinterferenz als Ursache unklarer Hypercalcitoninämie
Philipp Seifert
1  Clinic of Nuclear Medicine, Jena University Hospital, Jena, Germany
,
Elena Kloos
2  Institute of Medical Diagnostics, Jena Bioscientia Laboratory, Jena, Germany
,
Konstanze Ritter
3  Practice for Internal Medical and Thyroid Disease, Gera, Germany
,
Martin Freesmeyer
1  Clinic of Nuclear Medicine, Jena University Hospital, Jena, Germany
› Author Affiliations
This study was funded exclusively with intramural grants from the Jena University Hospital.
Further Information

Publication History

Publication Date:
20 January 2020 (online)

Introduction

Medullary thyroid carcinomas (MTCs) are rare tumors originating from the parafollicular C-cells and accounting for up to 10 % of all malignant thyroid neoplasms [1]. Because an early diagnosis is crucial for the prognosis, single calcitonin screening is recommended in nodular thyroid disease by German and European guidelines while the American guidelines are more restrained [2]. However, a large German cohort study based on health-insurance data revealed that calcitonin screening has only been performed in 9 % among patients who underwent surgery [3]. Reasons for the missing establishment in clinical practice are manifold containing uncertain upper limits, diagnostic ambiguities in case of slightly or mildly elevated calcitonin values, the rareness of MTCs, and the low test specificity in case of renal failure, proton-pump inhibitor medication, other malignancies, hypercalcemia, hypergastrinemia, various gastrointestinal and pulmonary diseases and non-medullary benign and malignant thyroid nodules [4]. Nonetheless, in our experience the method is gaining in acceptance as normal calcitonin levels can preclude the presence of MTCs. On the other hand, MTCs are highly probable at basal calcitonin levels of > 30 pg/ml in women and > 60 pg/ml in men, leading to the recommendation of consecutive thyroidectomy [2].

However, the automated immunometric assays used for calcitonin measurements are at risk of false results due to methodological specifics. Unintended metabolites such as heterophilic antibodies or macrocalcitonin may cause false results [5]. We report a clinically important case of obscure hypercalcitoninemia due to heterophilic antibody interference.