hello and thank you for your message,
what is exactly the use of measuring free T3 when TSH is suppressed and free
T4 is high? unless I have misunderstood something, if the patient is under
amiodarone therapy, free T3 can as well be high, normal or low in this case
(because amiodarone can decrease deiodinase activity more or less)
as I do not subscribe, I have no information about this case 230, and
therefore without any information my comment would be:
suppressed TSH and high free T4: the etiology of this frank primary
hyperthyroidism must be searched for and therefore the following other tests
might have to be ordered, maybe according to scintigraphy: auto-antibodies
anti-TSH receptors (in case of suspicion of Basedow disease), or anti-TPO
antibodies (anti-thyroglobuline are less useful, except in areas of iodine
deficiency), particularly if TSH is below 0,1mU/L and/or in case of IFN/IL2,
amiodarone, lithium therapy and/or pregnancy or miscarriage, or CRP and
thyroglobuline (in case of suspicion of De Quervain thyroiditis or
amiodarone-induced thyroiditis), or according to patient history ioduria (in
24 hours urines). It is useless to order free T3 in these contexts (free T3
costs +/-15 Euros).
maybe this comment could be combined somehow with yours which sounds to be a
good one to me although the schedules for the treatments that you are
proposing are missing (Consistent with amiodarone induced hyperthyroidism
despite normal FT3 as conversion of T4 to T3 is impaired by amiodarone. Stop
amiodarone if feasible and treat with carbimazole and a B-blocker if
symptomatic).
Dr Joseph Watine, PH, AIHP, PharmD, AAHU, EurClinChem
Laboratoire de Biologie Polyvalente
Centre Hospitalier Général
12027 Rodez Cedex 9
France
>From: Mohammad Al-Jubouri <[log in to unmask]>
>Reply-To: Mohammad Al-Jubouri <[log in to unmask]>
>To: [log in to unmask]
>Subject: Case 230 Interpretative comment conundrum
>Date: Tue, 24 Apr 2007 13:30:29 -0700
>
>Dear NEQAS participants:
>
>A median scoring comment was:
>¢Suppressed TSH and elevated free T4 with normal free T3 suggest amiodarone
>induced hyperthyroidism. Suggest radio-iodine uptake studies to assess
>whether this is related to a nodular goitre or destructive thyroiditis¢.
>A positive score of 0.89 was given.
>
>A high scoring comment was:
>¢Suppressed TSH and high free T4 consistent with hyperthyroidism. This may
>be precipitated by amiodarone, and Endocrinologist input in management is
>recommended. Normal free T3 may represent decreased deiodinase activity
>(possible amiodarone effect)¢.
>A positive score > 1.22 was given.
>
>My comment:
>
>Consistent with amiodarone induced hyperthyroidism despite normal FT3
>as conversion of T4 to T3 is impaired by amiodarone.Stop amiodarone if
>feasible and treat with carbimazole and a B-blocker if symptomatic.
>
>Can you guess my score?
>
>
>Any guess is welcome, you can be as ruthless as you can be or as generous
>as you like, no hard feelings either way.
>
>Best wishes
>
>Mohammad
>
>N.B: I can't understand why the median and high scoring comments insist on
>stating the obvious "suppressed TSH and high FT4", surely there is no added
>value to stating the obvious, but good on them if this gets them a high
>score.
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