Thyroid Uptake Exceeding 100%: Causes and Prevention

SummaryAim: Establishment of radioiodine treatment of feline hyperthyroidism in veterinary routine in accordance with German radiation protection regulations. Patients and methods: 35 cats with proven hyperthyroidism were treated with 131I in a special ward. Thyroid uptake and effective halflife were determined using gammacamera dosimetry. Patients were released when measured whole body activity was below the limit defined in the German “Strahlenschutzverordnung”. Results: 17/20 cats treated with 150 MBq radioiodine and 15/15 cats treated with 250 MBq had normal thyroid function after therapy, normal values for FT3 and FT4 were reached after two and normal TSH levels after three weeks. In 14 cats normal thyroid function was confirmed by controls 3-6 months later. Thyroidal iodine uptake was 24 ± 10%, effective halflife 2.5 ± 0.7 days. Whole body activity <1 MBq was reached 13 ± 4 days after application of 131I. Radiation exposure of cat owners was estimated as 1.97 Sv/MBq for adults. Conclusion: Radioiodine therapy of feline hyper-thyroidism is highly effective and safe. It can easily be performed in accordance with German radiation protection regulations, although this requires hospitalisation for approximately two weeks. Practical considerations on radiation exposure of cat owners do not justify this long interval. Regulations for the veterinary use of radioactive substances similar to existing regulations for medical use in humans are higly desirable.

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Ein objektanalytisches Verfahren zur Bestimmung der Fläche des nuklidspeichemden Schilddrüsenparenchyms im Szintigramm

Nuklearmedizin ◽

10.1055/s-0038-1629551 ◽

1991 ◽

Vol 30 (01) ◽

pp. 31-34

Author(s):

R. Kodym ◽

R. Seyss

Keyword(s):

Threshold Value ◽

Thyroid Uptake

An algorithm for object isolation was developed to determine the area of the thyroid in scintigraphic images, and its volume calculated therefrom so that operator-induced variations, common if the usual manual technique is used, could be avoided. The object isolation is performed for every possible threshold value. The resulting object isolation curves give a reliable and reproducible thyroid area. The method may be used routinely except in cases of blocked thyroid uptake or of multiple autonomous adenomas.

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SUBACUTE THYROIDITIS

Acta Endocrinologica ◽

10.1530/acta.0.xxxiii0457 ◽

1960 ◽

Vol XXXIII (III) ◽

pp. 457-472 ◽

Cited By ~ 6

Author(s):

B.-A. Lamberg ◽

G. Hintze ◽

R. Jussila ◽

M. Berlin

Keyword(s):

Thyroid Function ◽

Early Phase ◽

Radioactive Iodine ◽

Serum Proteins ◽

Conversion Ratio ◽

Subacute Thyroiditis ◽

Synthetic Analogues ◽

The Third ◽

Thyroid Uptake ◽

Iodine Metabolism

ABSTRACT A series of cases of clinically diagnosed subacute thyroiditis comprising 11 patients is reported. Studies on the iodine metabolism, electrophoretic distribution of the serum proteins and the responsiveness to TSH were carried out. The patients were observed for periods up to 16 months from the onset of the disease. In the early phase there was an elevation of the serum PBI in a few cases and hyperthyroid signs in some, accompanied by depressed thyroid uptake of radioactive iodine and a fairly good response to TSH. Later, the thyroid grew hard and the iodine metabolism changed. In several cases there was a marked increase in the conversion ratio and the serum PB131I level. The responses to TSH was variable for different parameters of thyroid function, suggesting a state of »low thyroid reserve« as defined by Jefferies et al. (1956). Hypothyroidism developed in 3 cases; in two of them there was a response to exogenous TSH, in the third no response was seen at this stage of the disease. Cortisone and synthetic analogues seem to be of great benefit in the treatment of the acute symptoms of the disease.

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