JOURNAL ARTICLE

Bone marrow dosimetry and safety of high 131I activities given after recombinant human thyroid-stimulating hormone to treat metastatic differentiated thyroid cancer

Bart de Keizer, Anne Hoekstra, Mark W Konijnenberg, Filip de Vos, Bieke Lambert, Peter P van Rijk, Cees J M Lips, John M H de Klerk
Journal of Nuclear Medicine 2004, 45 (9): 1549-54
15347723

UNLABELLED: Recombinant human thyroid-stimulating hormone (rhTSH) recently was introduced as a radioiodine administration adjunct that avoids levothyroxine (LT-4) withdrawal and resultant hypothyroidism. The pharmacokinetics of 131I after rhTSH administration are known to differ from those after LT-4 withdrawal but are largely nondelineated in the radioiodine therapy setting. We therefore sought to calculate the red marrow absorbed dose of high therapeutic activities of 131I given after rhTSH administration to patients with metastatic or inoperable locally recurrent differentiated thyroid cancer. We also sought to evaluate the clinical and laboratory effects of this therapy on the bone marrow.

METHODS: Fourteen consecutive patients received in total 17 131I treatments (7.4 GBq). Blood and urine samples were obtained at fixed intervals, and their activities were measured in a well counter. Based on blood activity, renal clearance of the activity, and residence times in red marrow and the remainder of the body, the red marrow absorbed dose was calculated using the MIRD schema. Additionally, we monitored for potential hematologic toxicity and compared platelet counts before and 3 mo after treatment.

RESULTS: The mean +/- SD absorbed dose per unit of administered (131)I in the red marrow was 0.16 +/- 0.07 mGy/MBq. The corresponding total red marrow absorbed dose was 1.15 +/- 0.52 Gy (range, 0.28-1.91 Gy). In none of the patients was hematologic toxicity observed. The mean +/- SD platelet count (n = 13 treatments) was 243 +/- 62 x 10(9)/L before treatment and 233 +/- 87 x 10(9)/L 3 mo later, a slight and statistically insignificant decrease. After rhTSH-aided administration of high activities of 131I, the bone marrow absorbed dose remained under 2 Gy, the level long considered the safety threshold for all radioiodine therapy.

CONCLUSION: Our specific findings imply that when clinically warranted, rhTSH should allow an increase in the therapeutic radioiodine activity. Such an increase might improve efficacy while preserving safety and tolerability; this possibility should be assessed in further studies.

Full Text Links

Find Full Text Links for this Article

Discussion

You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read
15347723
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"