Asian Journal of Medicine and Health Sciences Vol 1 November 2018

Radioiodine Ablation in Postpartum Patient with

Differentiated Thyroid Cancer: A Case Report and Review of
Literature.
Z A Zaid MBBS, H Fadzilah MMED, A K M Ali DMRD
Correspondence: Dr. Ahmad Zaid Zanial, Nuclear Medicine Department, Hospital
Pulau Pinang, Jalan Residensi, 10450 Pulau Pinang. Tel: 04-2002520

Abstract
Well differentiated thyroid carcinoma is the most commonly seen thyroid cancer. One of
the presenting symptoms is thyroid nodule. In most cases following initial workup and
whereby tumour is resectable, surgery is the mainstay of treatment. The subsequent
postsurgical management utilising radionuclide Iodine-131 (I-131) has long been
established and extensively being studied and discussed. This present case report
illustrates the general overview of differentiated thyroid cancer (DTC) as well as the
concerns related to radioiodine ablation in a postpartum patient with DTC.
Keywords: radioidine ablation, differentiated thyroid cancer, postpartum

Introduction underwent fine needle aspiration

Most commonly seen thyroid cancer cytology of thyroid nodule that revealed
cases are well differentiated thyroid malignant neoplasm with features
carcinoma (DTC). Patients may present suggestive of papillary carcinoma. She
with thyroid nodule or symptoms related was then advised for surgery and
to tumour extension, local spread and underwent total thyroidectomy on in
metastasis. Surgery is the mainstay of August 2013. Histopathological
treatment in the majority of cases examination of the surgical specimen
following initial workup whereby was reported as multifocal papillary
tumour is resectable. The subsequent thyroid carcinoma with possible vascular
postsurgical management would usually involvement and background features of
include the usage of radionuclide Iodine- multinodular goitre.
131 (I-131). However, there are several Postoperatively she was prescribed with
important recommended precautions and thyroxine. At that moment, she was also
preparation measures in optimising the confirmed to be pregnant in her second
treatment efficacy and safety plus trimester. She delivered her baby in
minimising the possible adverse effects November 2013 and subsequently
of I-131. These include concerns related breastfed the infant. She was then
to radioiodine ablation in postpartum reviewed at the Nuclear Medicine
patients and pre-ablation cessation of Department in March 2014 after being
breastfeeding. referred for remnant thyroid radioiodine
ablation. She was counselled regarding
Case Presentation the need for cessation of breastfeeding
A 40 years old lady with underlying and other pre-ablation preparations. No
hyperthyroidism was noticed to have a medication was prescribed to stop the
hard thyroid nodule in June 2013. lactation. She came for another clinic
Ultrasound of thyroid showed multiple review in April 2014. At that point, she
nodules in both thyroid lobes and has already stopped breastfeeding her
isthmus with some appearing irregularly child and being planned for radioiodine
hypoechoic with microcalcification. She ablation in May 2014.

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Asian Journal of Medicine and Health Sciences Vol 1 November 2018

Upon admission to the radioiodine ward, increased tracer uptake in the neck
there was no longer breast milk region with star effect in keeping with
production. She received radioiodine iodine-avid functioning thyroid tissue
ablation with 80 mCi of I-131 with prior (Figure 1 and 2). There was mild tracer
2 doses of intramuscular recombinant uptake seen in the soft tissue at the
human thyroid stimulating hormone anterior chest bilaterally due to non-
injections. Her TSH level was 78.94 pathological uptake in the breasts
µIU/mL and the stimulated serum (Figure 1 and 2). Elsewhere was
thyroglobulin level was < 1.0 µg/L. Day physiological uptake.
3 post ablation scan revealed 2 foci of

Figure 1. Post ablation scan - whole body anterior and posterior views.

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Asian Journal of Medicine and Health Sciences Vol 1 November 2018

Figure 2. Post ablation scan - spot views of the chest (anterior and right lateral views).
Discussion thyroglobulin level and findings of post
The oral administration of radionuclide ablative scan (2).
I-131 for the treatment of benign and Consequently decision related to the
malignant thyroid disorders has been a management with I-131 and selection of
commonly accepted procedure for the radioiodine activity is commonly
last 60 years (1). As for thyroid cancer, it directed by the disease stage and its risk
is the most common of the endocrine stratification. In our local setting,
malignancies with annual incidence radioiodine is being dispensed as liquid
varying considerably by geographic solution. The physical half-life of I-131
area, age and sex (2). DTC accounts for is approximately 8 days. I-131 emits beta
> 90% of thyroid cancer cases, with most particles at various energies with the
patients having an excellent prognosis maximal energy being 606 keV and the
(3). Although DTC can be divided into mean energy being 191 keV. It also emits
papillary, follicular and Hurtle cell gamma rays of 364 keV and 637 keV. As
subtypes, they all actually arise from the ionising radiation delivered by the beta
thyroid follicular cells. Most DTC cells particle loses its energy after travelling
preserve the ability to concentrate and about 2 mm in tissue, it disrupts chemical
retain iodine (4). bonds throughout the cell inflicting
A suspicious thyroid nodule is usually devastating damage on DNA molecules
being assessed by ultrasound and and triggering cellular dysfunction
cytology to ascertain the diagnosis. Total leading to ultimately cell death
or near-total thyroidectomy is the initial (In a most recent publication, it has been
treatment of DTC whenever the described that the use of radioidine in
diagnosis is made before surgery (2). It thyroid cancer generally can be divided
is widely recognised that I-131 has to 3 categories; (a) remnant ablation of
become an integral component of the thyroid tissue after surgery to facilitate
postsurgical management of DTC (5). future monitoring of thyroglobulin, (b)
Several published guidelines have adjuvant therapy after resection for
looked into the staging of DTC and its patients with increased risk of
risk stratification that incorporates recurrence, which mirrors adjuvant
tumour related parameters, histology and therapy in other solid cancers and (c)
other clinical factors including serum cancer treatment in an attempt to destroy
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Asian Journal of Medicine and Health Sciences Vol 1 November 2018

known or suspected active macroscopic

viable malignant disease (5). However, The patient in this case report was
there are also recommendations that postpartum and had breastfed her child at
certain cases such as unifocal papillary the time of referral for radioiodine
carcinoma < 1cm without any evidence ablation. She was advised to discontinue
of metastasis, capsule invasion, history lactation and delay the I-131 treatment
of radiation exposure and unfavourable until lactation has fully stopped.
histology would not require I-131 Nevertheless, in certain circumstances
ablation (7). some patients may require cautious use
There are several important preparations of short course of dopaminergic agents
prior to radioiodine treatment in order to such as bromocriptine and carbergoline
promote I-131 uptake and subsequently to stop lactation. Dopamine agonists
increase its effectiveness. For a sufficient could be beneficial in reducing breast
time before the contemplated therapy, exposure in recently lactating women,
patients must discontinue use of iodine although cautiousness should be
containing foods, supplements and exercised given the risk of serious side
medications. They should be on low- effects associated with their routine use
iodine diet for approximately 2 weeks to suppress postpartum lactation (9).
prior to radioiodine administration. Possible adverse effects include
Furthermore the serum TSH level prior gastrointestinal symptoms as well as
to radioiodine treatment should exceed cardiovascular, neurological and
30 µIU/mL in order to maximise I-131 psychiatric events.
uptake which could be attained by
withholding thyroxine hormones for Upon treatment, the presently discussed
about a month or by injection of patient no longer has breast milk
recombinant human TSH (1, 4). production. However, her post ablation
Pregnancy and breastfeeding are known scan showed iodine-avid tissue in the
contraindications to I-131 therapy. neck and mild tracer uptake in the breasts
Pregnancy must be excluded before each bilaterally. Added spot views were
treatment as radioiodine may cause acquired to exclude lung metastasis.
detrimental risks to the foetus. Women Radioiodine activity in the chest can be
who are lactating or have just recently due to uptake in the lungs, breasts, heart,
stopped breastfeeding also should not be thymus, trachea, oesophagus and
treated with I-131 since the lactating external contamination such as skin, hair
breasts may concentrate a substantial and garment (10). Radioiodine breast
amount of iodide. This is firstly to uptake has been reported to be unilateral,
prevent milk containing I-131 from asymmetrical or symmetrical bilaterally
being breastfed to the infant and in the patterns of full, focal, crescent or
secondly to limit radiation exposure of irregular uptake (11). In certain cases, a
the breast tissue which has increased pre-radioiodine therapy scintigraphy
expression of sodium iodide symporter with low dose Iodine-123 or
during lactation (8). Patients should be Technetium-99m pertechnetate can
advised to discontinue breastfeeding for reasonably be used to assess whether the
approximately 6-8 weeks before I-131 previously lactating breasts still
administration (4, 9). Cessation of concentrate iodine and guide appropriate
lactation should continue after the timing of the treatment (1, 12, 13).
therapy and breastfeeding can be Conclusion
undertaken with the birth of another Administration of oral radioiodine for
child (1, 8). the treatment of DTC has long been

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Asian Journal of Medicine and Health Sciences Vol 1 November 2018

established and became an important ensure adequate discontinuation of

aspect of the post-operative lactation prior to treatment with I-131.
management. There are several Cessation of lactation can be achieved
important recommended precautions and either physiologically or
preparation measures related to the pharmacologically. Despite that, mild
therapeutic use of radioiodine. In a radioiodine activity may still be present
postpartum patient with DTC who is in the breasts and must not be mistaken
referred for remnant thyroid radioiodine for pathological lung uptake.
ablation, measures should be taken to
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