? Tshoma


Question

I was hoping for some assistance with a case: 25 year old student of chinese descent. Presents with probably thyrotoxic periodic paralysis and TSH 10, FT4 40, FT3 12. Goitre noted, intermittent tachycardia and tremor. Patient well and no aware of symptoms. Pit MRI incl sinus views normal Alpha subunit elevated x 4 ULN. SHBG 2x ULN. Uptake scan increased at 15% TRH stimulation: increase from 10 to 16 mIU/L T3 suppression: no signficant change on doppler or TSH value (10 to 9) Questions: 1. Should we image this patient further or just observe with plans for repeat MRI? 2. Should we treat this patient with a somatostatin analogue (he has no had further episode of weakness at 3 months and is very well)? 3. Do you interpret the TRH stimulation as positive, borderline or negative? 4. Please tell me where I can get advise on how I can calculate the alpha subunit to TSH molar ratio

DR Kath Williams

Response

Very interesting case, indeed. I thing we are facing a patient with a TSH-oma on the basis of these findings:

1. High serum alpha-subunit levels (unless he has high levels of gonadotropins)

2. High serum SHBG levels (serum SHBG concentrations are normal in patients with thyroid hormone resistance (RTH))

3. Impaired TSH response to TRH

4. Failure to respond to T3 suppression test (RTH patients reduce TSH, though not to a complete suppression).

I suggest:

1. More precise MRI, possibly the "dynamic" one

2. Look for a possible ECTOPIC TSHoma

3. Do an Octreoscan

4. Treat the patient for at least 3 months with octreotide LAR or lanreatide Autogel, measuring FT4, FT3 and TSH the day before the analog injection.

Let us know of the results.Paolo Beck-Peccoz, M.D. University of Milan, Email:paolo.beckpeccoz@unimi.it