The TSH Test in Persons Having Received Iodine Compounds

Summary

The 2-hr ¹³²I thyroid uptake was measured serially in 5 groups of normal volunteers whereas the 2-hr and the 24-hr uptake of ¹³¹I were measured in a sixth group. Following administration of potassium iodide in doses of 40, 200 and 1000 mg, Urografin or Biligrafin i.v., the thyroid uptake decreased to very low values. A single injection thereafter of 10 I.U. of TSH increased these low values to levels within the normal range. A direct assessment of the individual level of thyroid function cannot be obtained by the described procedure because of lack of linear correlation between the values obtained for the PII and the uptake measurements after TSH administration. It is concluded that TSH can be used for differentiating low uptake values due to primary hypothyroidism from those after iodine ingestion in either inorganic or organic form. In such patients, TSH may also help in obtaining a better scintigram of the thyroid gland.

Résumé

La fixation thyroïdienne de ¹³²I à 2 h a été determinée chez 5 groupes de sujets normaux. Chez un sixième groupe la fixation de 2 et 24 h de ¹³¹I a été determinée. Après l’administration d’iodure de potasse à doses de 40, 200 et 1000 mg, ou Urografin et Biligrafin i.v., la fixation thyroïdienne a été fortement diminuée. Une simple injection de TSH a augmenté la fixation de ¹³¹I à des valeurs normales. En conclusion, la TSH peut aider dans le diagnostic différentiel entre malades avec hypothyroïdisme primaire et sujets qui ont reçu l’iode sous forme organique ou inorganique. Dans tels cas, une injection de TSH peut en plus nous aider à obtenir un scintigramme thyroïdien, ce qui pourrait être autrement difficile, vu les valeurs réduites de la captation thyroïdienne.

Die 2-Std.-¹³²J-Schilddrüsenspeicherung wurde an 5 Gruppen gesunder Personen bestimmt. In einer sechsten Gruppe wurde die 2- und 24-Std.-Schilddrüsenspeicherung von ¹³¹J bestimmt. Nach Verabreichung von KJ in Dosen zu 40, 200 und 1000 mg, und von Urografin und Biligrafin i.v., ist die Schilddrüsenspeickerung auf sehr kleine Werte herabgesetzt. Nach einer i.m. Injektion von 10 I. E. Thyreotropin (TSH) ist die Schilddrüsenspeicherung erhöht. Es wird daraus geschlossen, daß TSH in der Differential-Diagnose zwischen Kranken mit primärer Hypothyreose und Personen, die Jod in organischer oder inorganischer Form erhalten haben, helfen kann. Bei diesen Patienten kann TSH auch bei der Durchführung eines besseren Schilddrüsen-Szintigramms von Nutzen sein.

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