Misleading FT4 Result In A Patient With Hashimoto's Thyroiditis

[helvella]

This brief item appears to be critical of the primary care physician who high-handedly stopped long-term levothyroxine for a patient. Ignoring lack of symptoms of overdose, ignoring high TSH.

The PCP simply assumed the high fT4 was the important test result and wantonly ignored the high TSH result.

I think we have seen similar stories in many posts over the years. They are far, far more concerned about ONE single blood test result than the entire clinical presentation and, in this case, the other blood test result.

LBODP101 Misleading FT4 Result In A Patient With Hashimoto's Thyroiditis

Journal of the Endocrine Society, 01 Nov 2022, 6(Suppl 1):A741-A742

PMCID: PMC9625670

Abstract

Abstract Thyroid hormones and thyroid-stimulating hormone (TSH) laboratory tests are widely utilized worldwide, and their results have a significant impact on treatment decisions and subsequent diagnostic processes. In order to avoid misdiagnosis and inappropriate therapy, any differences between symptoms and laboratory findings should be thoroughly investigated. Many factors can cause discrepancies between thyroid function test and the patients’ clinical picture such as physiological changes, severe illness, drugs, or laboratory interference. Thyroid hormone autoantibodies, anti-streptavidin, and anti-ruthenium antibodies are the major thyroid function test interferers. Here, we present a case of a 70-year-old woman who is known to have hashimoto's thyroiditis maintained on Levothyroxine (LT4) for more than 10 years, but was stopped by her primary care physician due to abnormal thyroid panel results (high TSH and high fT4). She was referred to the endocrinology clinic for further evaluation. The patient complained of generalized fatigue and weakness. She had no hyperthyroid symptoms. She was not on any supplements. Testing thyroid hormones with the 2-step assay revealed severe hypothyroidism, so LT4 was resumed, and patient symptoms improved. This case aims to direct clinicians’ attention to the importance of considering the patient's clinical status in the diagnostic process and not replacing it with the laboratory diagnosis, given the possibility of many laboratories’ interference. Also, to underline the available methods to minimize false results and misleading diagnoses to avoid unnecessary investigations and interventions.

europepmc.org/article/PMC/P...

[arTistapple]

Another piece of research likely to mostly be ignored. Unless legal action taken. However the doctor is probably mostly protected by ‘protocols’. Even when they are told in the NICE regs, they still insist on the ‘results’ having priority. We can hope someone might care.

[tattybogle]

There are enough case studies available to produce a Tsunami of papers conveying this message ..... more than enough to completely bury the Tsunami of 'TSH is king' papers we are subjected to.

but how to incentivise Doctors to write them up ... that is the question.

[helvella Administrator Thyroid UK in reply to tattybogle]

A TSHunami?

The brief paper read as if they were being quite strongly critical of the PCP - which is relatively unusual.

[tattybogle in reply to helvella]

Saudi author ~ maybe PCP is Isreali

[serenfach]

I am going to use "laboratory diagnosis" for doctors in the future. Just to remind them I am not a lab rat, but a human!

[humanbean]

A question...

Would testing Free T3 have helped avoid this problem?

...

This link might be helpful for somebody :

Common Interferences in Thyroid Immunoassays

endocrinologyadvisor.com/ho...

The reference for the above is this - and it is open access :

Interferences With Thyroid Function Immunoassays: Clinical Implications and Detection Algorithm

academic.oup.com/edrv/artic...