Color flow doppler sonography (CFDS) is a powerful technique which displays tissue blood flow and vascularity.
Hyperthyroidism due to
Graves' disease is characterized by variable degrees of increased blood flow at CFDS. The purpose of this study was to evaluate CFDS patterns in five women with
thyrotoxicosis factitia, a condition due to surreptitious ingestion of excess
thyroid hormone. Diagnosis was supported by the finding of elevated free
thyroxine (FT4), ranging 24.2-67.6 pmol/L (normal values: 8.3-20.5), elevated free
triiodothyronine (FT3), ranging 9.9-26.7 pmol/L (normal values: 3.8-8.4), undetectable
thyrotropin (TSH), absent anti-thyroid
antibodies, undetectable serum
thyroglobulin (Tg) concentrations, very low/suppressed thyroidal radioiodine uptake and normal/low urinary
iodine excretion. Moreover, all patients admitted
thyroid hormone pills intake. All patients had normal thyroid volume and echogenicity at conventional sonography (mean estimated volume, 9.4 ml, range, 6-11 ml), and absent hypervascularity or minimal intrathyroidal vascular spots at CFDS. The peak systolic velocity (PSV) was at the lower limit of normal values (mean, 4 cm/sec, range 3-5 cm/sec). Twenty-six women with untreated
Graves' disease had an increase in the mean PSV, (mean 12.9 cm/sec, range 8-20, p < 0.001) and diffuse hypervascularity. CFDS pattern in 24 normal women residing in the same area did not differ from that found in patients with
thyrotoxicosis factitia. Thus, due to the nonthyroidal origin of excess
thyroid hormone, CFDS showed absent hypervascularity and normal PSV in spite of a thyrotoxic status. These findings well correlate with the etiology of
thyrotoxicosis factitia and may represent an additional, useful tool to confirm the diagnosis. For its easiness, rapidity (10 min) and noninvasive features, CFDS can be considered a first line test during office examination when
thyrotoxicosis factitia is suspected.