Dear colleagues,
My understanding of rapid changes in TSH is as follows. Like most pituitary hormones, TSH secretion and concentrations can change rapidly. A physiological example of this is the diurnal variation with TSH at midnight being about twice that of the daytime Nadir. The thought that TSH changes slowly (weeks) is related to the rate of change in T4 with changes in therapy. I do not find the changes surprising.
Regards,
Graham
Sent from my iPhone
> On 10 Aug 2016, at 1:33, "Agius Charlton at MDH-Health" <[log in to unmask]> wrote:
>
> Interesting case. Maybe biological potency of LT3 vs LT4 and intravenous route of TH administration could possibly account for such a suppression within 24 hours.
>
> Incidentally was the patient also given steroids and/or inotropic support with dopamine? May have contributed to TSH drop.
>
> Charlton
>
>
>
> Dr Charlton Agius
> BST Chemical Pathology
> Clinical Chemistry
> Pathology Department
> Mater Dei Hospital, Malta
> Ext: 2545 6370
>
>
>
>
>
>
> ________________________________________
> From: Clinical biochemistry discussion list [[log in to unmask]] on behalf of Mohammad Al-Jubouri [[log in to unmask]]
> Sent: 09 August 2016 15:12
> To: [log in to unmask]
> Subject: [SPAM] - T3 therapy & TSH suppression - Number of numbers in MIME From exceeds maximum threshold
>
> There is a belief that TSH requires at least 6 weeks to normalise/stabilise after starting/changing dose of thyroxine or lieothyronine replacement therapy.
>
> We recently had a case of myxoedema coma with the following TFTs on admission:
>
> FT4 4.4 pmol/L (Ref.11 - 22)
> FT3 2.00 pmol/L (Ref. 3.1 -6.8)
> TSH 68.1 mU/L (Ref.0.30 - 5.0)
>
> Started IV T3 therapy 10 mcg every 4 hours and after 5 doses (50 mcg), TFTs were checked next day and were as follows:
>
> FT4 3.7 pmol/L
> FT3 5.4 pmol/L
> TSH 15.3 mU/L
>
>
> All results were double checked and are analytically accurate.
>
> I consider this as a massive drop in TSH in response to 1 day of T3 therapy, is this what one would expect?
>
> I would be grateful to your comments.
>
> Regards
>
>
> Mohammad
>
>
> Dr. M A Al-Jubouri, MB ChB, MSc, EurClinChem, FRCP Edin, FRCPath
> Consultant Chemical Pathologist
>
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