Sample preparation for in vitro anallysis of iodine in thyroid tissue using x-ray fluorescence

• Iodine is enriched and stored in the thyroid gland. Due to several factors, the size of the thyroid iodine pool varies both between individuals and within individuals over time. Excess iodine as well as iodine defi ciency may promote thyroid cancer. Therefore, knowledge of iodine content and distribution within thyroid cancer tissue is of interest. X-ray fl uorescence analysis (XRF) and secondary ion mass spectrometry (SIMS) are two methods that can be used to assess iodine content in thyroid tissue. With both techniques, choice of sample preparation affects the results. Aldehyde fi xatives are required for SIMS analysis while a freezing method might be satisfactory for XRF analysis. The aims of the present study were primarily to evaluate a simple freezing technique for preserving samples for XRF analysis and also to use XRF to evaluate the effi cacy of using aldehyde fi xatives to prepare samples for SIMS analysis. Ten porcine thyroids were sectioned into four pieces that were either frozen or fi xed in formaldehyde, glutaraldehyde, or a modifi ed Karnovsky fi xative. The frozen samples were assessed for iodine content with XRF after 1 and 2 months, and the fi xed samples were analyzed for iodine content after 1 week. Freezing of untreated tissue yielded no signifi cant iodine loss, whereas fi xation with aldehydes yielded an iodine loss of 14–30%, with Karnovsky producing the least loss.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

thyroid

iodine

X-ray fl uorescence

secondary ion mass spectrometry

fi xation

sample preparation

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