Postpartum thyroid dysfunction occurs in 510% of women in the general population within one year of delivery. The prevalence of postpartum Graves disease is estimated at 0.54%. Postpartum thyroiditis is much more common. Differential diagnosis is essential for an adequate treatment. Radioactive iodine uptake can be useful to establish the etiologic diagnosis, but is contraindicated during lactation. Elevated titers of antithyrotropin receptor antibodies (TRAbs) are suggestive of Gravess disease but may be measurable in approximately 10% of patients with painless thyroiditis and their titers can be low in the early phase of Graves disease. Therefore, the evolution of thyroid function and TRAbs titers may be needed to distinguish both pathologies. We present the case of a 25-year-old Caucasian woman who presented to the Emergency Department, 4 months after giving birth and still breastfeeding, complaining of palpitations, anxiety, fatigue and insomnia with 1 week of duration and referring a 15 kg weight loss postpartum. She mentioned that her mother had Graves disease. There was no ophthalmopathy; her heart rate was 140 bpm and the electrocardiogram confirmed sinus tachycardia. Thyroid examination showed a painless tender and slightly enlarged gland. Blood tests TSH 0.011 uU/nl (0.34.2), FT3>20 pg/ml (2.34.2) and FT4 5.33 ng/dl (0.931.7). She was referred to the Endocrinology Department under treatment with methimazole and propranolol. Further testing revealed positive anti-thyroid peroxidase and thyroglobulin antibodies and TRAbs within grey zone. Thyroid function was monitored with slowly tapering of methimazole dosage. Eight months postpartum, despite low methimazole dosage (2.5 mg id) she presented with asymptomatic hypothyroidism (TSH>100 uU/ml). Anti-thyroid antibodies remained positive but TRAbs were negative. Methimazole was suspended and levothyroxine 25 mcg id initiated. At last follow-up, the patient remains asymptomatic and in euthyroidism. Diagnosis of postpartum thyroiditis was assumed. Monitoring thyroid function and TRAbs levels for several months might be necessary to allow the differential diagnosis.
20 - 23 May 2017
European Society of Endocrinology