Development of hyperthyroidism following primary hypothyroidism: a case report

Autoimmune Thyroiditis Shifting from Hashimoto's Thyroiditis to Graves' Disease

In 15-20% of cases, Graves' disease (GD) shifts to Hashimoto's thyroiditis (HT), while the shift from HT to GD is rare. We present a case of a patient in whom HT shifted to GD, along with a literature review. A 50-year-old woman with myxedema was diagnosed with Hashimoto's disease due to hypothyroidism and the presence of antibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TgAb); she also had thyroid stimulating antibodies (TSAb) without any signs of GD. Although thyroid hormone replacement therapy improved her thyroid function, 2 months later, hyperthyroidism appeared and did not improve after discontinuation of the replacement therapy. The patient was diagnosed with GD, which improved with antithyroid agent administration. To date, only 50 cases regarding conversion from HT to GD have been reported. The median age is 44 years (range, 23-82 years), and the median time of conversion is 7 years (range, 0.1-27 years). The male-to-female ratio of HT conversion to GD is 1:9, closer to that of regular GD (1:10) than that of general HT (1:18). All patients received thyroid hormone replacement therapy for hypothyroidism due to HT. Continuous evaluation of TSAb levels is recommended in HT, particularly in cases of TSAb-positive and those under replacement, since it may help predict conversion to GD. Evaluating the clinical characteristics of patients with HT preceding GD is crucial to ensure appropriate treatment and reduce the risk of adverse events.

New-Onset Graves’ Disease in the Background of Hashimoto’s Thyroiditis: Spectrums of the Same Disease With Changing Autoantibodies

Hashimoto’s thyroiditis and Graves’ disease represent two spectrums of the same autoimmune thyroiditis. Evolution from Graves’ disease to Hashimoto’s thyroiditis is a common scenario but conversion is a rare occurrence that we observed in the presented case of a 56-year-old Hispanic female with a history of Hashimoto’s thyroiditis with positive anti-thyroperoxidase (TPO) antibodies who was euthyroid on levothbefore75 µg for six years prior to her presentation to the emergency department (ED) with complaints of palpitations, exertional dyspnea, and unintentional weight loss of 20 lbs for four months. The patient denied any recent change in levothyroxine dosage. The patient was noted to have tachycardia at rest, hyperdynamic circulation, and fine tremors on outstretched hands-on examination but no exophthalmos, thyromegaly, or pedal swellings. Her initial laboratory workup revealed thyroid-stimulating hormone of <0.01 mIU/L, with elevated free T3 and free T4 levels. Levothyroxine was held and beta-blockade therapy was started for symptom control. Further workup showed elevated thyroid-stimulating immunoglobulin and thyroid receptor antibody levels and normalization of anti-TPO antibody levels. The radioactive iodine uptake scan was initially delayed because the patient underwent a pulmonary angiogram in the ED. A later scan showed thyromegaly with heterogeneous uptake of 82% in both lobes. Hence, the patient was diagnosed with Graves’ disease and managed with radioactive iodine ablation therapy. On follow-up, the patient developed post-ablation hypothyroidism; she was started back on levothyroxine therapy and became euthyroid. This case highlights that patients can develop Graves’ disease in the background of a hypothyroid state, and this conversion might be postulated secondary to a combination of atypical destructive thyroiditis and a switch of autoantibodies from blocking to stimulating ones. Clinicians should suspect the possibility of changing antibodies when there is a change in the patient’s euthyroid state.

The clinical phenotype of Graves' disease occurring as an isolated condition or in association with other autoimmune diseases

PURPOSE

Graves' disease (GD) can present as an isolated disease (iGD) or in association with other autoimmune diseases (aGD). The aim of this study, performed in two Endocrine referral centers settled in different geographical areas of Italy, was to compare the anthropometric, clinical, and biochemical phenotype of iGD patients with that of the aGD ones.

METHODS

Clinical history, physical examination data, serum levels of TSH, FT4, FT3, thyroglobulin (TgAb), thyroid-peroxidase (TPOAb) and TSH-receptor (TRAb) antibody, presence of Graves' orbitopathy (GO), and thyroid ultrasound examination at disease diagnosis were recorded.

RESULTS

68 aGD and 136 iGD patients were consecutively recruited. At diagnosis, aGD and iGD patients did not differ for F/M ratio, age at presentation, thyroid function parameters, serum levels of TRAb, TgAb, TPOAb, presence of GO, and thyroid volume. The serum levels of TRAb were strongly correlated with the circulating concentrations of both FT3 (ρ = 0.667; p < 0.0001) and FT4 (ρ = 0.628; p < 0.001) in iGD patient, but not in the aGD ones (FT3: ρ = 0.231; p = 0.058; FT4: ρ = 0.096; p = 0.435). Compared with iGD patients, the aGD ones displayed a higher rate of transition from the previous hypothyroidism to hyperthyroidism (χ² = 6.375; p = 0.012).

CONCLUSION

Despite similar anthropometric, clinical, and biochemical features at diagnosis, aGD patients display a higher rate of transition from a thyroid functional status to the other as compared with iGD patients.

Conversion of Primary Hypothyroidism to Hyperthyroidism: A Case Report

A 51-year-old Caucasian male developed Graves’ thyrotoxicosis following long-standing treatment for hypothyroidism. After a short period of treatment with carbimazole, he developed agranulocytosis and required total thyroidectomy. In this relevant case report, we review several pathogenetic mechanisms that explain the transformation of autoimmune hypothyroidism into Graves’ disease and the possible approaches to the management of agranulocytosis secondary to antithyroid medications. Further studies are required to determine the best way to manage severe thyrotoxicosis when agranulocytosis develops due to antithyroid medications.

Conversion of autoimmune hypothyroidism to hyperthyroidism

BACKGROUND

Graves' disease and Hashimoto's thyroiditis are the two autoimmune spectrum of thyroid disease. Cases of conversion from hyperthyroidism to hypothyroidism have been reported but conversion from hypothyroidism to hyperthyroidism is very rare. Although such cases have been reported rarely in the past we are now seeing such conversions from hypothyroidism to hyperthyroidism more frequently in clinical practice.

CASE PRESENTATION

We are reporting three cases of middle aged Asian females who presented with classical symptoms of hypothyroidism and the investigations showed elevated thyroid stimulating hormone with positive thyroid antibodies. Diagnosis of autoimmune hypothyroidism was made and thyroxine replacement therapy was initiated. Patients became asymptomatic with normalization of thyroid stimulating hormone level. After few years they developed symptoms of hyperthyroidism with suppressed thyroid stimulating hormone level. Over replacement of thyroxine was considered and the dose of thyroxine was decreased, but they remain symptomatic. After gradual decrease in the dose of thyroxine it was stopped finally. Even after few months of stopping thyroxine, the symptoms of hyperthyroidism did not improve and the biochemical and imaging modalities confirmed that the patients have developed hyperthyroidism. Anti-thyroid treatment was then started and the patients became symptom free.

CONCLUSION

High index of suspicion should be there for possible conversion of hypothyroidism to hyperthyroidism if a patient with primary hypothyroidism develops persistent symptoms of hyperthyroidism. Otherwise it can be missed easily considering it as an over replacement with thyroid hormone.

Transient Graves' hyperthyroidism during pregnancy in a patient with Hashimoto's hypothyroidism

The course and severity of autoimmune thyroid disease are altered during pregnancy and in the postpartum period. The thyroidal response to a fluctuating immune status, combined with changes in thyroid economy during pregnancy, may result in a need to adjust the treatment regimen for thyroid disease during pregnancy. Patients with Hashimoto's hypothyroidism on thyroid hormone replacement are frequently observed to have an increased requirement for levothyroxine early in pregnancy, although this is not a universal finding. Hashimoto's hypothyroidism does not typically remit during pregnancy, although further progression of thyroiditis may be seen in the postpartum period. Graves' disease usually improves during pregnancy and flares after delivery, again necessitating monitoring of thyroid status and possible adjustments in thionamide therapy. However, spontaneous transformation from Hashimoto's hypothyroidism to Graves' disease during pregnancy is rare. We report a case of transient Graves' hyperthyroidism during the late second trimester in a patient on levothyroxine replacement for Hashimoto's hypothyroidism. This resulted in a need to discontinue the patient's thyroid hormone entirely to avoid exacerbation of her hyperthyroidism. This interesting case is presented, along with a discussion of how the expression of autoimmune thyroid disease may be altered during pregnancy.