Discordant TFT After Total Thyroidectomy: Challenges of Diagnosing Resistance to Thyroid Hormone
https://doi.org/10.15605/jafes.041.S1
- Author:
Tan Jia Miao
1
;
Pavai Sthaneshwar
2
;
Shireene Ratna Vethakkan
1
Author Information
1. Endocrine Unit, Department of Medicine, University Malaya
2. Chemical Pathology Unit, Department of Pathology, University Malaya
- Publication Type:Journal Article
- MeSH:
Thyroidectomy;
Thyroid Hormones
- From:
Journal of the ASEAN Federation of Endocrine Societies
2026;41(S1):110-111
- CountryPhilippines
- Language:English
-
Abstract:
Introduction:Thyroid hormone resistance syndrome (THR) is a disorder
characterized by reduced responsiveness of target tissues
to thyroid hormones with non-suppressed thyroidstimulating hormone (TSH) despite elevated free thyroxine
4 (FT4). Diagnosing and managing THR in athyreotic
patients, however, is challenging; indeed, TSH levels post
thyroidectomy for Differentiated Thyroid Carcinoma in
patients with THR have been reported to reach levels as high
as 112.59 mIU/L despite high-dose thyroxine-suppressive
therapy. This case highlights the complexities in diagnosing
Resistance to Thyroid Hormone (RTH) post-thyroidectomy.
Case:A 63-year-old female with end-stage renal failure (ESRF)
on hemodialysis and prior parathyroidectomy for tertiary
hyperparathyroidism underwent total thyroidectomy in
1997 for presumed benign goiter. Following surgery, she
demonstrated persistently elevated TSH, ranging from 93.2
to 670.4 mIU/L (0.55–4.78 mIU/L), with normal to mildly
elevated FT4 levels, ranging from 17 to 35 pmol/L (11.5–22.7
pmol/L), while on thyroxine replacement doses as low as
0.86 ug/kg. Discordant thyroid function tests (TFTs) were
consistent across different assay platforms. Polyethylene
glycol precipitation excluded macro-TSH interference.
Intermittent levothyroxine increments suppressed TSH but
led to thyrotoxic symptoms, including weight loss, heat
intolerance, insomnia, and fragility fracture. Uncontrasted
pituitary magnetic resonance imaging (risk of nephrogenic
systemic fibrosis with gadolinium in ESRF) showed a small
pituitary gland without adenoma, excluding TSH-oma.
T3 suppression test was relatively contraindicated due to
her advanced age and co-morbidities. There was no family
history of thyroid disorder; the patient’s only child had a
normal TFT, and her parents/siblings could not be tested. A
working diagnosis of RTHβ was made. She declined genetic
testing for RTH. She is currently on levothyroxine 50 mcg
OD (1.07 ug/kg) with FT4 16.1 pmol/L and TSH 562 mIU/L
with no symptoms/signs of hypo or hyperthyroidism.
Conclusion:This case highlights the diagnostic challenges in managing
possible RTHβ post-total thyroidectomy. Treatment should
be guided by clinical status and target of mid-to-normal
FT4 rather than TSH to avoid iatrogenic thyrotoxicosis.
- Full text:2026080508365364521EP_A163.pdf
