Onset of Graves' disease during pregnancy in a woman with established hypothyroidism.
BACKGROUND
Pregnancy strongly influences the thyroid gland and its function. Thyroid guidelines recommend a 30 to 50% increase of the preconceptional levothyroxine dose in women with hypothyroidism, when pregnancy is diagnosed.


METHODS
A 33 year-old, 8-week pregnant woman with hypothyroidism, presents with a 2-week history of palpitations, sweating, nervousness and fatigue. Physical examination shows tachycardia (108 bpm), distal tremors and diffuse goiter. After biochemical confirmation of hyperthyroidism, her levothyroxine dose is reduced and finally interrupted. Propylthiouracil is started and maintained until after the delivery of a healthy baby at week 40. Two weeks postpartum, hyperthyroidism worsens and propylthiouracil is replaced by methimazole. Eighteen months after delivery 7.5 mCi 131Iodine was given. Two months later, hypothyroidism developed and levothyroxine was initiated.


CONCLUSIONS
Although conversion of Hashimoto's hypothyroidism into Graves' disease is exceptional in pregnancy, pregnant women with autoimmune hypothyroidism should ideally have their TSH concentrations measured before empirically increasing their levothyroxine dose.
a Servicio de Endocrinología y Nutrición, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Universidad de Las Palmas de Gran Canaria , Las Palmas de Gran Canaria , Spain.
María
M
Alberiche
a Servicio de Endocrinología y Nutrición, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Universidad de Las Palmas de Gran Canaria , Las Palmas de Gran Canaria , Spain.
Rosa María
RM
Sánchez-Hernández
a Servicio de Endocrinología y Nutrición, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Universidad de Las Palmas de Gran Canaria , Las Palmas de Gran Canaria , Spain.
Xabier
X
López Mérida
a Servicio de Endocrinología y Nutrición, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, Instituto Universitario de Investigaciones Biomédicas y Sanitarias, Universidad de Las Palmas de Gran Canaria , Las Palmas de Gran Canaria , Spain.
Ana María
AM
Wägner
D000328:Adult; D005260:Female; D006111:Graves Disease / Q000097:blood; D006801:Humans; D007037:Hypothyroidism / Q000097:blood; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood
Hyperthyroidism; hypothyroidism; pregnancy