Abstract

IJNM

Indian Journal of Nuclear Medicine

0972-3919

Society of Nuclear Medicine, India

ijnm-19-4-session-007

Session VII

122004

194150153

How Small Should be the Dose of Iodine-131 to Treat Thyrotoxicosis Patients?

Anand

Y N I

¹Rajini

T R

²Sankar

²Muthu

G S

¹The Nucleus, No 3, "I" Block, Kuvempunagar, Mysore - 570 023, drynianand@rediffmail.com²Department of Imaging Sciences, Meenakshi Mission, Hospital and Research Centre, Lake Area, Melur Road, Madurai - 625 020³Tata Main Hospital, Jamshedpur, Jharkhand, India

Ref. No: 50YNEND1

AbstractIntroduction

Madurai, otherwise known as the "Temple City", is located 500 km South of Chennai, the capital city of Tamil Nadu, in the Southern part of India. Meenakshi Mission Hospital and Research Centre, is a tertiary hospital catering to the needs of several hundred smaller hospitals and over 10 million people. The incidence of thyroid disorders is like anywhere else in the country. This is the only hospital in a radius of 200 km that offers Radioiodine treatment for patients of Thyrotoxicosis. We have treated nearly 200 patients over the last 6 years. Several patients belong to the lower socio-economic strata of the society and are unable to afford even the low, one-time cost of treatment with radioiodine-131. Hence they are advised to report for follow up for a period of one year from the date of administration of the final dose, or if they have any adverse but anticipated effects of radioiodine administration. Most of the patients were followed up at intervals of from six weeks to three months. The period of review varied from three months to five years in some cases. We present the data pertaining to 125 patients that was analyzed retrospectively to find out if the dose of radioiodine and the number of doses (sittings) had any effect on the final outcome during the period of observation.

Objectives

To Evaluate the Lowest Dose of ¹³¹I that Could be Used to Treat Patients of Thyrotoxicosis

Methods

Of the total of One hundred and twenty five patients, there were 104 cases of Graves' disease, 20 cases of Toxic nodular goiters and one case of Hashimoto's disease who subsequently developed Thyrotoxicosis. There were 42 men and 83 women in the ratio of 1:2 and in the age group between 15 and 67 years. The average age of men was 38 years and of women was 41 years. The overall average age was 40 years. Majority of the patients were in the age group between 21 and 50 years. Minimum and maximum doses administered were 4 mCi and 30 mCi respectively in one to three sittings. Seventeen patients were given two doses and five patients were given three doses. 29 patients were administered doses of less than 5 mCi, 64 patients were administered 5 mCi and 32 patients were administered more than 5 mCi. Of the 125 patients, 84 were treated from 01 Jan 2002 to 30 Aug 2003.

Results

29 patients developed hypothyroidism and 18 patients were still toxic when last reviewed. 78 patients were rendered euthyroid and many of them were advised to report only in case of development of hypothyroidism. 24 patients developed hypothyroidism within the first year of administration of radioiodine. 27 patients developed hypothyroidism after the first dose itself. Of these, 7 patients developed hypothyroidism with doses of less than 5 mCi, 16 patients with doses of 5 mCi and 6 patients with doses of more than 5 mCi. 12 patients remained hyperthyroid after the first dose, 5 after the second dose and 1 after the third dose. 78 patients, that is, 62% were euthyroid when last seen.

Conclusions

In the absence of a consensus on the exact dose for the management of thyrotoxicosis, we recommend low (5 mCi or less), rather than high dose of radioiodine when multiple doses are planned, as has been done in this subset of South Indian population.

Key wordsThyrotoxicosisLowest Dose of ¹³¹IHypothyroidism.

Preoperative Localization of Parathyroid Adenoma by Technetium-99m Sesta MIBI Scans-An Early Experience

Khan

Shoukat H.

Department of Nuclear Medicine, Sher-I-Kashmir Institute of Medical Sciences, Srinagar, 190011, J & K.

Ref. No: 51SKEND4

AbstractObjective

A preoperatively localized solitary parathyroid adenoma, the commonest lesion in 85-90% of patients with primary parathyroidism can be conveniently excised by performing a limited unilateral neck exploration with results comparable to the traditional bilateral neck exploration. This limited procedure in addition to requiring a shorter operating time has lesser complication rate and better cosmetic results. Various useful noninvasive techniques for localizing parathyroid adenomas are ultrasonography, computerized axial tomography magnetic resonance imaging and single or dual isotopic imaging. Localization techniques are invaluable in parathyroid adenomas situated at ectopic sites like mediastinum and also in patients with failed initial neck exploration requiring a second surgery. The aim of the present study is to find the usefulness of dual phase ^99mTc Sesta MIBI imaging in localizing the parathyroid adenoma.

Methods

12 patients with a clinical diagnosis of primary hyperparathyroidism with elevated paratharmone levels were prospectively studied. A dual phase parathyroid imaging was done after intravenous injection of 15-25 mill curies (Approximately 740 MBq) of ^99mTc labeled Sesta MIBI under a large field of view gamma camera fitted with a low energy parallel hole collimator. A positive scan for parathyroid adenoma was defined as an area of increased uptake that persisted in the delayed image at 90 minutes post injection.

Results

A positive parathyroid localization scan was seen in 9 (75%) patients. After unilateral neck exploration all these patients were confirmed to have the solitary adenoma at the preoperatively localized site. The paratharmone levels normalized in all the patients after the excision from the mean preoperative level of 414.46 Pg/ml dropped to a postoperative mean level of 43 Pg/ml Among 3 (25%) patients with negative scans subjected to bilateral neck exploration 1 patient had a solitary adenoma, 1 patient had multiglandular disease (Hyperplasia) and in 1 patient no lesion was found. Histopathology confirmation of a parathyroid adenoma was established in all the patients. The positive predictive value of the ^99mTc Sesta MIBI parathyroid localization scan in this study was 100%.

Conclusions

The present study reinforces the observations regarding the role of a relatively easy to perform ^99mTc Sesta MIBI scan in preoperative localization of a parathyroid adenoma. An accurate localization helps in minimizing the extent of neck exploration and reduces the associated complications. The role of expensive rapid intraoperative paratharmone assay and frozen sections in preoperatively well localized solitary parathyroid adenoma is debatable.

Key wordsParathyroid adenomahyperparathyroidism

Is Isotopic Immunoassay Relevant Today?

Khanna

Hazra P

Hazra

Gupta

Sharma

Nuclear Medicine Unit, S N Medical College and Boston Medical Centre, Agra 282005

Ref. No: 52PKEND3

AbstractIntroduction and Objectives

Ultra sensitive immunometric assays began with the TSH immunoradiometric assay (Hazra 1975; Hazra et al 1976), which enable the simultaneous sensitive diagnosis of both hypothyroidism and hyperthyroidism, and constitute the single most widely used endocrine assay today, being employed not only for diagnosis of overt disease but also subclinical disease and to decide about when to modulate or stop therapy. However there is a profusion of nonisotopic assays using CELIA/ECLIA/fluorophores/enzyme or other nonisotopic labels which are offered at far more expense to the patient on the grounds of novelty/enhanced sensitivity/ freedom from radiohazard. Are isotopic assays still relevant? For this analysis, this was examined in 2 contexts: endocrinology and oncology.

Methods

In this context the relevance of isotopic assays versus nonisotopic assays as perceived today was assessed by surveying internists/endocrinologists/oncologists using a confidential computer coded questionnaire. Respondents were asked to grade on a 5 point scale their assessments of the cost/ clinical relevance/reliability/turn around time of various assays/ laboratories for both endocrine and tumour ligands.

Results

While most clinicians agreed that decision levels were not influenced by changes in hormone levels even at the first decimal place, there were several who construed fourth decimal and third decimal results as probably more accurate! Many clinicians graded the various assays in terms of novelty interpreted as modernity rather than in terms of precision profile or bias or adherence to quality control. Some clinicians graded the assays solely by economy/metropolitan origin/presentation format of report/incentives.

Conclusions

Clinicians need to be informed about what really matters in choosing an assay or a laboratory.

The quality control philosophy is still not prevalent amongst assay laboratories.

Assays continue to provide critical decision making input information in endocrinology and oncology.

Key wordsImmunoradiometric AssayNon-isotopic AssaysHypothyroidism

Role of Thyroid Parotid Ratio in the Diagnosis of Thyroid Dysfunction

Pradhan

Das B

Pawaskar

Deswal

Kumar

Veeresh

Dubey

Gambhir

Shukla

Department of Nuclear Medicine, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow

Ref. No: 53PPEND5

AbstractObjectives

Most of the Thyroid patients consult a physician due to problems associated with morphological, functional or both disorders of the gland. It is the responsibility of the concerned physician to make an objective diagnosis of the problem before initiating therapeutic measures. Thyroid to Parotid Ratio (TPR) was introduced as a simple and cost effective parameter and has been evaluated in various functional disorders of the thyroid gland like Graves' disease, Thyroiditis etc. The purpose of this presentation is to document our further experience with this parameter in the background of patients coming from a large endemic goiter region.

Material and Method

A total of 870 consecutive patients who were referred to our department between January 1996 and December 2002 for diagnosis or therapy are included in this study. After thorough history and clinical examination all patients were subjected to Tc-99m Thyroid scan and T3, T4 , TSH besides other investigations as per specific requirement. Thyroid to Parotid Ratio (TPR) was calculated after drawing Regions of Interest (ROI) over the Thyroid and both parotid glands in anterior projection. The TPR values were derived by taking ratio of activity per pixel and were compared with biochemical parameters like T3, T4, and TSH and with the results of other investigations.

Results

All the 252 patients having diffuse or nodular goiter with euthyroid function had a TPR value below 2.52 ( mean TPR + 2 SD in normal volunteers ).Out of 578 patients having Hyperthyroidism 515 had a TPR value more than 2.52 and 63 patients had TPR less than 2.52. T3 and T4 values were high in 512 patients and normal in 66 cases. In 18 patients who were clinically hypothyroid 12 had low TPR (< 2.52) whereas 6 showed TPR more than 2.52. Five of them later found to have iodine avidity and one dyshormonogenesis. In 22 patients clinically suspected to have Thyroiditis, 14 had low TPR whereas 8 revealed higher values of TPR. All these patients had also high T3 and T4 values and in follow up found to be suffering from mild hyperthyroidism. The sensitivity and specificity of TPR has been calculated to be 93.7% and 88.57% respectively.

Conclusions

In our experience TPR is an extremely useful parameter for speedy diagnosis of thyroid dysfunction and particularly helpful for patients coming from far off places who can not pay and also wait for results of biochemical parameters which do not provide any additional information in most of the cases.

Key wordsThyroid to Parotid Ratio (TPR)Graves' DiseaseThyroiditis

Hypothyroidism in Pregnancy: Management of Mother and Effects on the Foetus.

Shankar

L Ravi

Sekhri

Sharma

Sripathy

Institute of Nuclear Medicine & Allied Sciences, Brig S. K. Mazumdar Road, Delhi - 110 054

Ref. No: 54RSEND6

AbstractObjectives

Thyroid hormones are essential for normal growth, sexual development, and, reproductive function. Numerous hormonal changes and metabolic demands occur during pregnancy, and thus pregnancy and the postpartum period are times of marked and rapid change in the thyroid gland, that need to be recognized, carefully assessed, and, correctly managed. A project was taken up on the management of hypothyroidism in the mother during pregnancy and study the effects on the foetus.

Methods

All patients taken up for this study were on treatment for hypothyroidism at our Institute. 71 cases were taken up in this study , the age group was 18-32 years, average being 24.6 + 2.2 yrs. FT3, FT4, TSH, Thyroglobulin antibody (Tg) and Thyroid Peroxidase antibody (TPO) was done prior to pregnancy, after they were brought to a euthyroid state with thyroxine replacement therapy for hypothyroidism, in the 1^st, 2^nd, 3^rd trimesters and post delivery. The same tests were also done for the newborns in the 1^st week after delivery, and, in the event of the FT4 or TSH not being in the normal range, these were repeated within 3 weeks after birth. Prior to pregnancy the average thyroid hormone status of the patients was FT3 -3.3+ 1.24 pg/ml(N-2.3-4.2pg/ml),FT4-1.06 + 0.21 ng/dl(N - 0.89 -1.8 ng/dl), TSH - 2.04 + 1.12 µiu/ml (N - 0.35 - 5.5 µiu/ ml). Tg was positive in 24 cases whilst TPO was positive in 54 cases.

Results

Of the 71 cases, 37 patients required an increase in the replacement dose in the first trimester due to fall in the FT4 levels or a rise in the TSH concentration. After increase in the replacement dose of thyroxine in the first trimester, 3 patients required a further increase in the dose during pregnancy. Of the remaining patients, 7 patients required an increase in the thyroxine replacement dose during the other two trimesters of pregnancy. Of the 54 TPO and 21 Tg positive cases, only 8 and 2 respectively were positive at delivery. Patients requiring increase in dosage were antibody positive. Average FT3, FT4 and TSH levels in the newborn was 3.9 + 1.2 pg/ml, 1.32 + 0.63 ng/dl, and 5.1 + 3.2 µiu/ml respectively. TSH levels were raised in 24 of the 71 newborn. Of these 23 reverted back to within normal limits within 3 weeks after birth.

Conclusions

To conclude we would suggest that there should be a close monitoring of hypothyroid women during pregnancy, euthyroid status should be maintained, and, the newborn be examined and evaluated immediately after birth.