American Association of Clinical Endocrinoligist's (AACE) 23rd Annual Scientific and Clinical Congress:
G2 P2 Patient Presents to Emergency Room with Hyperthyoidism
Thyroid function testing may be ordered by an obstetrician because of potential complications associated with thyroid dysfunction and pregnancy. However, test results can be difficult to interpret, and not all the changes that occur to thyroid function during pregnancy are pathologic. Therefore, it is important for practitioners to be able to distinguish between pathology and physiology to ensure the patient receives appropriate treatment.
During the 23rd Annual Scientific and Clinical Congress of the American Association of Clinical Endocrinology, Lauren Maxham, MD of the University of Nevada School of Medicine (Las Vegas, NV) presented Twins or Hyperthyroidism? A Look at Thyroid Function Tests in Pregnancy.
“This is a case of a 30-year-old woman, G3 P2, without significant medical history who presented to the emergency room with palpitations, heat intolerance, fatigue, nausea, and vomiting,” explained Dr. Maxham. Laboratory and ultrasound tests were positive for 10 weeks twin gestation.
The patient’s physical examination, which included her thyroid gland was unremarkable. An EKG revealed sinus tachycardia. Her serum human chorionic gonadotropin (hCG) was >225000 mIU/ml, thyroid-stimulating hormone (TSH) <0.0100 (0.350-4.940 uIU/mL), free thyroxine 4 (FT4) was 2.82 (0.70-1.48 mg/dl), and FT3 was 6.6 (1.7-3.7 pg/ml).
Dr. Maxham indicated, “Because of the severity of her symptoms, she was started on propylthiouracil (PTU). Later, her thyroid-stimulating immunoglobulin and anti thyroid peroxidase antibodies were found to be within normal limits. She was discharged with PTU and referred to a high-risk obstetrician.” The patient required PTU throughout her pregnancy.
hCG and TSH Receptor
This case illustrates how important it can be to distinguish pathologic and physiologic changes in thyroid function during pregnancy because it is known that hCG does have a weak affinity for the TSH receptor. However, there are many case reports that show—in high concentrations, hCG can lead to significant stimulation of the TSH receptor. “In our patient, she had a twin pregnancy and had higher baseline hCG levels than a normal pregnant woman,” stated Dr. Maxham.
Maxham L, Izuora K. Twins or Hyperthyroidism? A Look at Thyroid Function Tests in Pregnancy. Abstract #1171. Presented at the American Association of Clinical Endocrinologists 23rd Annual Scientific and Clinical Congress, Las Vegas, NV. May 14-18, 2014.