Radioactive iodine therapy in Graves' hyperthyroidism: a prospective study from a tertiary referral centre in north India

BACKGROUND

Radioactive iodine has gained widespread acceptance as the first-line therapy for Graves' hyperthyroidism and is the preferred treatment option in most situations.

OBJECTIVE

A prospective study was conducted to look at the therapeutic practice of use of radioactive iodine in the treatment of Graves' hyperthyroidism, to determine whether the expected or desired therapeutic outcome is achieved.

SETTINGS

A tertiary referral centre in north India, Delhi that caters to patients with thyroid disorders.

METHODS

One hundred and seventy four consecutive subjects with Graves' hyperthyroidism, who were given radioactive iodine were followed up.

RESULTS

There were 59 (33.9%) males and 115 (66.1%) females. The mean age was 41.8 +/- 9 years. The dose of radioactive iodine ranged from 2 mCi to 15 mCi and the mean dose administered was 5.2 +/- 1.9 mCi. After one year following radioactive iodine therapy, 29 (16.7%) subjects were euthyroid, 51 (29.3%) were hypothyroid and the remaining 94 (54%) had persisting hyperthyroidism. Those subjects with persisting hyperthyroidism at one year after radioactive iodine had received a significantly lower dose compared to the groups who had achieved cure (either euthyroidism or hypothyroidism).

CONCLUSION

The study shows that the current practice of empirical low dose radioactive iodine therapy to avoid hypothyroidism results in majority of patients having persisting hyperthyroidism. There is a need to take a new look at the current practice to increase the cure rate.

Familial aggregation of autoimmune thyroiditis in first-degree relatives of patients with juvenile autoimmune thyroid disease

Several studies have shown aggregation of autoimmune thyroiditis in families by estimation of thyroid antibodies. However, the prevalence by concurrent estimation with fine-needle aspiration cytology (FNAC) and thyroid antibodies has not been previously reported. We therefore studied 222 first-degree relatives (group 1) of 71 index cases diagnosed as lymphocytic thyroiditis on FNAC and 81 family members (group 2) of 23 goitrous children diagnosed as colloid goiter on FNAC for comparison. Successful FNAC conducted in 122 group 1 subjects revealed lymphocytic thyroiditis in 51 (42%), whereas lymphocytic thyroiditis was diagnosed in only 5 goitrous subjects (13%) in group 2. Among group 1 subjects with FNAC-proven lymphocytic thyroiditis, antithyroid peroxidase (TPO) antibodies were found in 35 (67%), while in anti-TPO antibody positive goitrous relatives of group 1, lymphocytic thyroiditis was found in 36 (78%). Eight new cases of overt hypothyroidism and 45 new cases of subclinical hypothyroidism were diagnosed among group 1 subjects. Our study suggests: (1). familial clustering of autoimmune thyroiditis; (2). if only FNAC or thyroid antibodies is used for diagnosis of autoimmune thyroiditis in children, 22%-33% of cases are likely to be missed; and (3). serum thyrotropin (TSH) should be offered to all first-degree relatives of patients with juvenile autoimmune thyroiditis.

Clinical, biochemical and cytomorphological observations in juvenile chronic lymphocytic thyroiditis

OBJECTIVE

To determine the clinical, biochemical, ultrasonological and cytomorphological features in goitrous juvenile chronic lymphocytic thyroiditis(CLT).

SETTING

Tertiary referral center for thyroid disorders.

SUBJECTS

A total of 455 children were evaluated for goiter. Of these 122 children had features of CLT in FNAC and were further studied.

METHODS

All subjects were subjected to detailed clinical examination. The thyroid functional status was assessed by estimation of serum concentration of thyroid hormones (thyroxine and triiodothyronine) and thyrotropin (TSH). In addition the antithyroid antibody titers were measured. Ultrasonological and cytomorphological characteristics in these patients were also evaluated.

RESULTS

The mean age at presentation was 12.5 years (SD 3.93). The male: female ratio was 1:7.7. Thyroid functional status as assessed by serum thyroxine and thyrotropin levels revealed, euthyroidism in 67 (54.9%), hypothyroidism in 30 (24.6%), subclinical hypothyroidism in 22 (18%) and hyperthyroidism in 3 (2.5%). Thyroid antimicrosomal antibodies were detected in significant titers in 90 (73.8%) and antithyroglobulin was positive in 71 (58.2%). The positivity of the antimicrosomal and antithyroglobulin antibodies were much higher in subjects with hypothyroidism and was detected in 86.5% and 69.2%, respectively. The mean urinary iodine excretion was 74.1 micrograms/g of creatinine (SD 31.4) indicating mild iodine deficiency. Fine needle aspiration cytoloty (FNAC) revealed features of chronic lymphocytic thyroiditis. Hurthle cell changes was seen in only 12% of the cases. The epithelium was more often hyperplastic and vacuolation of the cytoplasm and peripheral vacuolations were seen frequently. Giant cells and epithelioid cells were seen in many cases.

CONCLUSIONS

In any child presenting with firm goiter, a diagnosis of CLT should be excluded. Many subjects with juvenile CLT have biochemical evidence of hypothyroidism but only few symptoms or clinical features.

Thyrotoxicosis--treatment by I131 therapy and early prediction of hypothyroidism following this therapy

This study was undertaken in 68 thyrotoxic patients to assess the predictive value of various post treatment biochemical and immunological tests for early hypothyroidism after I131 therapy and to determine whether pretreatment with carbimazole protects against post I131 therapy hypothyroidism. Early changes observed in serum T3, T4, TSH, thyroid microsomal and thyroglobulin antibody levels were found to be of no predictive value. A sharp increase in TRAb levels around 3 months following I131 therapy indicated that hypothyroidism was likely to occur as this rise reflected a greater degree of thyroid damage. Lower levels of thyroglobulin in patients who became hypothyroid by 12 months after treatment would support this view. Carbimazole pretreatment for eight weeks did not appear to protect against hypothyroidism, in our study.