Measurement of reverse triiodothyronine level and the triiodothyronine to reverse triiodothyronine ratio in dried blood spot samples at birth may facilitate early detection of monocarboxylate transporter 8 deficiency

Hideyuki Iwayama, Hiroki Kakita, Masumi Iwasa, Shinsuke Adachi, Kyoko Takano, Masahiro Kikuchi, Yasuko Fujisawa, Hitoshi Osaka, Yasumasa Yamada, Akihisa Okumura, Khemraj Hirani, Roy E. Weiss, Samuel Refetoff

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Monocarboxylate transporter 8 (MCT8) deficiency is an X-chromosome-linked neurodevelopmental disorder resulting from impaired thyroid hormone transport across the cell membrane. The diagnosis of MCT8 deficiency is typically delayed owing to the late appearance of signs and symptoms as well as the inability of standard biomarkers of neonatal screening to provide early detection. In this study, we report, for the first time, the ability to detect MCT8 deficiency at birth using dried blood spot (DBS) samples. Methods: We retrospectively measured triiodothyronine (T3), thyroxine (T4), and reverse T3 (rT3) levels in DBS samples obtained at 4–5 days of life from 6 infants with genetically confirmed MCT8 deficiency and from 110 controls. The latter consisted of 58 healthy term neonates obtained at the same time, 16 were stored for more than 1 year before measurement to match samples from the MCT8-deficient infants. Ten DBS samples were collected at day 1 of life and 42 samples were from prematurely born neonates. Measurements were carried out in extract from eight millimeters diameter DBS using liquid chromatography-tandem mass spectrometry. Results: Contrary to characteristic iodothyronine abnormalities of MCT8 deficiency during later life, T3 and T4 values were not discriminatory from those of other study groups. In contrast, rT3 was significantly lower. The T3/rT3 ratio was higher in the DBS samples from the MCT8-deficient infants compared with all other groups with no overlap (p < 0.0001). Conclusions: rT3 and T3/rT3 ratio in DBS samples obtained from neonates can serve as biomarkers to detect MCT8 deficiency at birth.

Original languageEnglish (US)
Pages (from-to)1316-1321
Number of pages6
JournalThyroid
Volume31
Issue number9
DOIs
StatePublished - Sep 1 2021

Keywords

  • Dried blood spot
  • LC-MS/MS
  • MCT8 deficiency
  • Newborn screening
  • Reverse T3

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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