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Time-dependent changes in FT4 and FT3 levels measured using mass spectrometry after an acute ingestion of excess levothyroxine in a case with hypothyroidism.

Thyrotoxicosis is widespread dysfunction amongst endocrine dysfunctions. It is just not uncommon that the free thyroid hormone degree exceeds the measurement vary of immunoassay. Such excessive excessive focus of free thyroid hormone is mostly thought-about to be not possible to measure appropriately as a result of of changes in the steadiness between free hormones and binding proteins by dilution of serum.

Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), nonetheless, increased concentrations are capable of be decided.We current a case of a 21-year-old feminine with congenital hypothyroidism who had taken a whole of 5 mg levothyroxine over three consecutive days following discontinuance of the remedy for a month.

Immunoassay carried out three hours after the final ingestion confirmed that the affected person’s free thyroxine (FT4) was over 100 pmol/L and her free triiodothyronine (FT3) was 24.5 pmol/L. With a non permanent cessation of levothyroxine, the affected person was saved for remark with out some other remedy. Two days after the final ingestion, FT4 was nonetheless over 100 pmol/L and FT3 was elevated to 28.8 pmol/L.

After an extra four days, each FT4 and FT3 levels decreased. Through this era, no thyrotoxic symptom or bodily signal had appeared. We additionally measured FT4 and FT3 levels in her cryopreserved serum by ultrafiltration LC-MS/MS.

Her FT4 degree measured by ultrafiltration LC-MS/MS on the visiting day and 2 days later have been 160.0 and 135.5 pmol/L, respectively, indicating that the poisonous dose of levothyroxine was partly modified to T3 through the 2 days. The FT3/FT4 ratios have been revealed to be low, accounting for the affected person’s benign scientific course regardless of temporal poisonous publicity to levothyroxine. It is implied that prior discontinuation of supplementary levothyroxine will increase potential vacant binding websites for thyroid hormone as a buffer to forestall poisonous T3 impact.

Time-dependent changes in FT4 and FT3 levels measured using mass spectrometry after an acute ingestion of excess levothyroxine in a case with hypothyroidism.
Time-dependent changes in FT4 and FT3 levels measured using mass spectrometry after an acute ingestion of excess levothyroxine in a case with hypothyroidism.

It was useful to make clear the time dependent changes in free thyroid hormone levels by ultrafiltration LC-MS/MS in discussing the scientific course in this case.

Though mass spectrometry has a drawback in velocity for routine laboratory use, its correct measurement, notably of levels exceeding the measurable vary of the immunoassay, supplies worthwhile info for extra applicable administration of excessive thyrotoxicosis.

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