Tc-99m-tetrofosmin thyroid scan in patients with low I-131 thyroid uptake.

UNLABELLED: Low 24-hour thyroid uptake of I-131 (I-131 uptake) is a common finding that influences evaluation of the thyroid gland.

METHODS

We studied 20 female patients aged 16-82 years with low I-131 uptake. The following causes of reduced I-131 uptake were defined as (A) six cases with subacute thyroiditis, (B) seven cases with T4 suppression therapy, and (C) seven cases with iodinated pharmaceuticals use. Thirty-minute Tc-99m tetrofosmin thyroid scan was performed within 24 hours of the I-131 thyroid study.

RESULTS

The results were correlated with neck ultrasound, serum TSH and biopsy histopathological findings. Tc-99m tetrofosmin thyroid scans revealed 10 normal thyroids, five diffuse goiters, four multinodular goitres, and one solitary thyroid nodule.

CONCLUSIONS

Our results suggest that Tc-99m tetrofosmin thyroid scans may provide additional information to diagnose thyroid pathology in patients with low 24-hour I-131 uptake.