Evidence map›Paper›PMID 41485920›Full record

ReviewInternal medicine (Tokyo, Japan)2026

Spuriously Elevated Free Thyroxine Due to Fibrin Interference in a Patient Receiving Apixaban: A Case Report and Literature Review.

Takahiro Suzuki, Kenji Ohba, Akiko Agata, Shiori Takebayashi, Keita Yamashita, Mitsuaki Tokumaru, Hiroshi Ukigai, Ryosuke Takeuchi, Takayuki Iwaki, Hirotomo Saitsu and 2 more

Abstract readCase ReportsReview
PubMed Full text at PMC Publisher
In one paragraph

Review in Internal medicine (Tokyo, Japan), 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

12 authors.

Takahiro SuzukiDepartment of Gastroenterology, Hamamatsu Red Cross Hospital, Japan.
Kenji OhbaMedical Education Center, Hamamatsu University School of Medicine, Japan.
Akiko AgataDepartment of Clinical Laboratory Technology, Hamamatsu Red Cross Hospital, Japan.
Shiori TakebayashiDepartment of Laboratory Medicine, Hamamatsu University School of Medicine, Japan.
Keita YamashitaDepartment of Laboratory Medicine, Hamamatsu University School of Medicine, Japan.
Mitsuaki TokumaruSecond Division of Internal Medicine, Hamamatsu University School of Medicine, Japan.
Hiroshi UkigaiDepartment of Internal Medicine, Hamamatsu Red Cross Hospital, Japan.
Ryosuke TakeuchiDepartment of Cardiology, Hamamatsu Red Cross Hospital, Japan.
Takayuki IwakiDepartment of Pharmacology, Hamamatsu University School of Medicine, Japan.
Hirotomo SaitsuDepartment of Biochemistry, Hamamatsu University School of Medicine, Japan.
Masato MaekawaDepartment of Laboratory Medicine, Hamamatsu University School of Medicine, Japan.
Yuko SuzukiDepartment of Internal Medicine, Hamamatsu Red Cross Hospital, Japan.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Fibrin interference can cause spurious immunoassay results, particularly in patients with coagulopathy or those receiving anticoagulant therapy. We report the case of an asymptomatic 79-year-old woman treated with apixaban, who presented spuriously elevated free thyroxine and free triiodothyronine levels, mimicking a syndrome of inappropriate secretion of thyroid-stimulating hormone. Plasma measurements revealed values within the reference range, which confirmed fibrin interference. To our knowledge, this is the first case to demonstrate fibrin interference in thyroid function testing during direct oral anticoagulant therapy. The relevant literature suggests a greater susceptibility to specific free thyroxine assay platforms. Clinicians should recognize this phenomenon to avoid unnecessary investigation of apparent thyroid dysfunction.

Indexed as

Factor Xa InhibitorsFibrinPyrazolesPyridonesThyroxineAgedFemaleHumansThyroid Function TestsapixabanFactor Xa InhibitorsFibrinPyrazolesPyridonesThyroxineDOACfibrin interferenceFT4SITSH

Identifiers

PMID41485920
PMCPMC13521625

What OpenQuestion holds

Textmetadata
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.