Klinisches Bild und mögliche Ursachen der Funktionsstörungen der Glandula parotis bei der Radiojodtherapie des differenzierten Schilddrüsenkarzinoms*

Abstract

Bei 31 Patienten, die sich wegen eines differenzierten Schilddrüsenkarzinoms nach Thyreoidektomie einer Radiojodtherapie unterziehen müssen, wird die Funktion der Glandula parotis untersucht. Die Untersuchurig erfolgt jeweils unmittelbar vor Therapiebeginn und eine Woche danach. Neben einer akuten Steigerung der Natrium-, Protein-und a-Amylasenkonzentration im Sekret nach jeder Einzeltherapie zeigte sich eine zunehmende Einschrankung der FluI.rate und der Aktivität der a-Amylase in Abhängigkeit von der kumulativen Gesamtdosis. Die Bedeutung des glandularen Kallikreins und der Phosphohexoseisomerase (PHI) werden im Hinblick auf eine mögliche Drusenschadigung diskutiert. Hierbei werden Vergleiche zur chronisch-rezidivierenden Parotitis angesteilt und therapeutische Aspekte angesprochen. Insgesamt zeigen die Befunde, da die Radiojodtherapie, ähnlich wie die externe Strahlentherapie, eine chronische Funktionsstorung der Drüse bewirkt, die im ailgemeinen nach einer kumulatiyen Gesamtdosis von 470 mCi zu meIbaren Veranderungen führt. Clinical Aspects and Possible Causes of Parotid Gland Dysfunction in Radioactive Iodine Therapy * Vorgetragen bei der 71. Versammlung der südwestdeutschen Hals-Nasen-Ohren-Arzte.

RETRACTED ARTICLE: Radiation Sialadenitis Induced by High-dose Radioactive Iodine Therapy

“…The simultaneously injured irradiated intralobular ducts lose their ability to filter and prevent plasma proteins from entering the saliva. As a result of these two mechanisms, elevated protein values are evident in parotid saliva [9,15]. Elevated sodium and chloride levels are also found in parotid saliva because a radiationdamaged duct does not have the normal duct's ability to resorb these electrolytes secreted by the terminal acinar cells as saliva progresses through the duct system.…”

Radioactive Iodine and the Salivary Glands

“…As a result of these two mechanisms, elevated protein values are evident in parotid saliva. [9,15] Elevated sodium and chloride levels are also found in parotid saliva because a radiation-damaged duct does not have the normal duct's ability to resorb these electrolytes secreted by the terminal acinar cells as saliva progresses through the duct system. Furthermore, salivary phosphate levels are decreased when the damaged epithelium of the intralobular duct's wall fails in its normal function to transport phosphate into the saliva.…”

Ionizing irradiation and the salivary gland sequelae

“…Due to their size, location and bilateral symmetry, it is inevitable that at least a portion of the major salivary glands will be included in most radiation fields, deliv ered to control and abate the primary malignant neoplasm and/ or its common cervical lymph node metastasis (5). Even radio therapy modalities such as total body irradiation delivered pri or to bone marrow transplantation, mouth field irradiation ad ministered while treating Hodgkin's lymphoma or radioactive iodine therapy given for thyroid carcinoma, all expose salivary glands to the severe effect of ionizing irradiation (6)(7)(8). The se vere negative impact that xerostomia has on the patient's life results from various secondary effects, such as impairment of taste, mastication, swallowing, speech and sleep patterns.…”

“…This xerostomia is ra pid in appearance following low doses. Doses of up to 10 Gy, usually given within the first week of therapy, may reduce the salivary flow by as much as 50-60% (5)(6)(7)(8)(9)(10)(11)(12)(17)(18)(19)(20). The parotid gland is affected early following irradiation, demonstrating a rapid reduction of its secretion capacity and especially "at rest" rather than "at stimulated" conditions (17,20).…”

“…Within a few hours after low-dose irradiation (1 -4 Gy), a profound, 10 to 80 fold increase ofthe parotid amylase isoenzyme is found. This elevation reaches its peak within 12-36 hours and may be the result of immediate serous cell death ofthe parotid gland, accompanied by disruption ofthe cellular membrane and leakage ofthe secretory enzyme into the extracellular space and the blood circulation (6,7,(27)(28)(29)(30)(31)(32)(33). Another immediate clinical finding is enlargement ofthe major salivary glands, occasionally painful.…”