sodium-pertechnetate-tc-99m and Fever

Hyperthermia may be a consequence of environmental conditions, bacterial or viral infections and/or thyroid storm. This study investigates the acute effect of body temperature elevation on thyroid function and on its scintigraphy studies. Thyroid scintigraphy was performed on New Zealand White rabbits weighing approximately 3-3.5 kg. Each rabbit was injected with 115 MBq (3.1 mCi) technetium-99 m pertechnetate ((99m)Tc pertechnetate). Studies were performed using Gamma camera equipped with a low energy, high resolution, pinhole collimator interfaced with a computer. Static images were acquired 20 min after administration of the radiotracer. Two days later the same protocol was repeated for the same rabbit after increasing the body temperature by 2 degrees C. The experiment was repeated again after a 2-day interval at 3 degrees C, and then after another 2-day interval at 4 degrees C. Plasma free thyroxine (FT(4)), free triiodothyronine (FT(3)) and thyroid stimulating hormone (TSH) were measured at control and at different hyperthermic temperatures (+2, 3, 4 degrees C). We recorded isometric tension of rabbit thyroid artery strips in organ baths during stepwise temperature elevation. During hyperthermia the decrease in thyroid function and thyroid scintigraphy studies was proportional to body temperature elevation. The recording of isometric tension in rabbit thyroid artery strips in organ baths showed vasoconstriction during hyperthermia which is proportional to the heating temperature. Plasma FT(4) and FT(3) level were decreased while TSH levels were not affected by acute fever. Our results indicate that hyperthermia causes a transient decrease in thyroid gland function and scintigraphic patterns on radionuclide studies. Thus, body temperatures must be measured before radionuclide studies in order to ensure that interpretation of data is not influenced by hyperthermia.

Topics: Animals; Arteries; Artifacts; Body Temperature; Disease Models, Animal; Down-Regulation; Fever; Male; Rabbits; Radionuclide Imaging; Radiopharmaceuticals; Regional Blood Flow; Sodium Pertechnetate Tc 99m; Thyroid Function Tests; Thyroid Gland; Thyrotropin; Thyroxine; Triiodothyronine; Vasoconstriction

Topics: Abdominal Pain; Anorexia; Appendicitis; Child; Diagnosis, Differential; Diarrhea; Diverticulitis; Fever; Humans; Male; Meckel Diverticulum; Peritonitis; Radionuclide Imaging; Radiopharmaceuticals; Sodium Pertechnetate Tc 99m; Tomography, Spiral Computed; Vomiting

We present the case of a 41-year-old man admitted to the hospital with fever and toxic syndrome possibly having an oncological or infectious origin. A whole body scan with 67Ga-citrate showed an intense and diffuse radiotracer accumulation in the thyroid gland. The patient was re-evaluated and studied with other diagnostic tests including a thyroid 99mTc-pertechnetate scintigraphy and a thyroidal radioiodine uptake. A correct final diagnosis of painless subacute thyroiditis was made.

Topics: Adult; Anorexia; Citrates; Deglutition Disorders; Diagnosis, Differential; Diagnostic Errors; Fever; Gallium; Gallium Radioisotopes; Humans; Iodine Radioisotopes; Male; Paraneoplastic Syndromes; Pharyngitis; Radionuclide Imaging; Radiopharmaceuticals; Sodium Pertechnetate Tc 99m; Thyroiditis, Subacute; Tuberculosis