[Changes in the blood picture after radioiodine therapy of thyroid cancer]

In this study the effect of radioiodine which was administered because of thyroid carcinoma on blood count and various other parameters was examined.

In 567 patients who had been treated because of a thyroid carcinoma between 1980 and 1990 with radioiodine, changes of hemoglobin, RBC, WBC, platelets, potassium, uric acid, gamma GT, GOT, GPT and AP were measured in correlation with the totally administered dose.

In low doses (< 18.5 GBq [500 mCi]), which are sufficient in most cases with clinical course without complications, relevant changes of blood count (hemoglobin: < or = 9.0/10.5 g/dl, RBC: < or = 3.1/3.5 10(12)/l (female/male), WBC: < or = 2.5 10(9)/l, platelets: < or = 0.5 10(11)/l) were observed in only 5 out of 469 cases. After moderate doses (> or = 18.5 GBq [500 mCi] and < 37 GBq [1000 mCi]) we found in only 1 out of 77 cases relevant changes. After very high doses (> or = 37 GBq [1000 mCi]), which are used to treat metastases and/or recurrences, thrombopoesis is most sensitive to the radiation exposure of the bone marrow. Relevant decrease of RBC and WBC were observed in 2 out of 21 patients. Pancytopenia (hemoglobin: < or = 12.0/13.5 g/dl, RBC: < or = 3.9/4.3 10(12)/l [female/male], WBC: < or = 3.5 10(9)/l, platelets: < or = 1.4 10(11)/l) occurred in 4 cases.

In high-dose therapy with radioiodine frequent (monthly, but in any cases before each therapy) controls of blood count are necessary. In patients without metastases or recurrence no relevant changes can be expected in most cases.