Thyroid function tests, incongruent internally and with thyroid status, both in a pregnant woman and in her newborn daughter

Abstract

Introduction: Thyroid function tests (TFT) are extensively used in daily clinical practice. Here we described a case of incongruent TFT both in a pregnant woman and in her newborn. Case presentation: A 32-year-old woman, diagnosed with autoimmune thyroiditis during her first pregnancy, was monitored during her second gestation. At week 5+2 days, TSH and FT4 values, (Dimension VISTA 1500, Siemens Healthineers) were within normal limits. At week 19+5 days, TSH remained normal while FT4, increased approximately by 3-fold. FT4 inconsistency was with both TSH and the clinical status, since she continued to be clinically euthyroid. On the same serum sample, thyroid autoantibodies were negative. At week 25+4 days, the patient complained of palpitations and dyspnea, with tachycardia. Even though TSH was normal, high levels of both FT4 and FT3 were interpreted as evidence of thyroid overactivity and methimazole was started. TFT of the pregnant woman continued to be monitored up throughout gestation. Postpartum FT4 and FT3 gradually returned to normal. TFT, performed on daughter’s serum, three days after birth, showed the same inconsistency of her mother but without clinical signs of congenital hyperthyroidism. Based on the clinical and laboratory setting, the presence of circulating autoantibodies against T3 and T4 (THAb) were suspected and demonstrated by radioimmunoprecipitation. Conclusion: Analytical interferences should be supposed when TFT do not fit with the clinical picture and despite their infrequency, THAb must also be considered. To our knowledge, this is the first case describing the passage of THAb to the newborn.

Eating Disorders: Causes, Symptoms, Diagnosis and Management

“…Electrolyte abnormalities are prevalent and must be assessed to rule out hyponatremia from excessive water consumption, hypokalemia from excessive purging, or hypocalcaemia and hypomagnesaemia from incorrect laxative usage. Thyroid function, as well as plasma ferritin, folate, and vitamin B12, should be evaluated (Ben-Zeev et al, 2022;D'Aurizio et al, 2022;Fang et al, 2022).…”