title: Quantitative measurement of thyroid blood flow for differentiation of painless thyroiditis from Graves' disease.
abstract: OBJECTIVE
  Differentiation between destruction-induced thyrotoxicosis and Graves' thyrotoxicosis is important for selection of proper therapy. It is, however, often difficult to make this distinction without measurement of radioactive iodine uptake. We investigated the possibility that assessment of thyroid blood flow would allow differentiation between the two entities.
  
  
  METHODS
  One hundred and fourteen untreated patients with thyrotoxicosis (56 Graves' disease, 28 painless thyroiditis, 30 subacute thyroiditis) and 25 normal controls were examined. Serum levels of freeT4 (FT4), freeT3 (FT3) and TSH were measured by chemiluminescent immunoassay, and anti-TSH receptor antibodies (TSH-binding inhibitory immunoglobulin, TBII) were measured by enzyme-linked immunosorbent assay. Thyroid volume and blood flow (TBF) were measured quantitatively by ultrasonography.
  
  
  RESULTS
  TBF was significantly higher in Graves' disease (mean +/- 1SD: 14.9 +/- 6.4%, P < 0.0001) than in painless thyroiditis (0.8 +/- 0.5%), subacute thyroiditis (0.9 +/- 0.7%) and in normal controls (0.8 +/- 0.5%). All patients with Graves' disease had TBF values of more than 4% and all patients with painless thyroiditis and subacute thyroiditis had TBF values less than 4%. TBF values significantly correlated with values of radioactive iodine uptake (RAIU) either at 3 h (r = 0.492, P < 0.01) or 24 h (r = 0.762, P < 0.001) within the Graves' disease and painless thyroiditis groups. There was no relationship between TBF values and thyroid volumes or values of TBII in the Graves' disease group. All patients with Graves' disease had positive TBII of 15% or more. Three of 28 patients with painless thyroiditis and one of 30 patients with subacute thyroiditis had positive TBII.
  
  
  CONCLUSIONS
  TBF was quantitatively measured by power Doppler ultrasonography and was more effective than TBII for differentiation between destruction-induced thyrotoxicosis (painless or subacute thyroiditis) and Graves' thyrotoxicosis. TBF values of less than 4% in untreated thyrotoxic patients are laboratory signals of destruction-induced thyrotoxicosis and if these are determined, the radioactive iodine uptake test can be omitted for differential diagnosis of these two types of thyrotoxicosis.
authors: Kuma Hospital, Kobe, Japan.
authors: Hisashi
authors: H
authors: Ota
authors: Nobuyuki
authors: N
authors: Amino
authors: Shinji
authors: S
authors: Morita
authors: Kaoru
authors: K
authors: Kobayashi
authors: Sumihisa
authors: S
authors: Kubota
authors: Shuji
authors: S
authors: Fukata
authors: Naohisa
authors: N
authors: Kamiyama
authors: Akira
authors: A
authors: Miyauchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006111:Graves Disease / Q000175:diagnosis*; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D012039:Regional Blood Flow; D018709:Statistics, Nonparametric; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000098:blood supply* / Q000000981:diagnostic imaging; D013963:Thyroid Hormones / Q000097:blood; D013966:Thyroiditis / Q000175:diagnosis*; D018617:Ultrasonography, Doppler, Pulsed
chemical_list: D007457:Iodine Radioisotopes; D013963:Thyroid Hormones