Calcitonin Changed During Pregnancy in MEN2A With MTC Patient: A Case Report
Authors: Porntharukchareon Thachanun , Chutpiboonwat Phronpan , Tangjittrong Sirinrat , Houngngam Natnicha , Snabboon Thiti 
Published: May 2021

Abstract
Background: The diagnosis of MTC during pregnancy was challenging. No definite calcitonin (Ct) cut-off level during pregnancy was defined. Moreover, cytology analysis accuracy in MTC was lower than other thyroid cancers. Stevenson et al. reported that the plasma Ct levels in pregnant women were much higher than normal women. The change in Ct levels during pregnancy was not well described. In this report, we present a case of a pregnant woman with recurrent MTC. The change in Ct levels during pregnancy, diagnosis methods, and proper management were presented here.
Clinical Case: A 31-year Thai woman, gravida 2, para 0 at 17 weeks of pregnancy, previously diagnosed with MTC and treated with total thyroidectomy and neck dissection seven years ago. During antenatal care at 14 weeks of pregnancy, the Ct level was 126 pg/ml (raised from 34 pg/ml seven years ago). The neck’s USG demonstrates vascularized hypoechoic lesion at the right thyroid bed with multiple nodules. The Ct wash-out test from this lesion was 200,000 pg/ml. The cytology study showed several clusters of atypical cells possessing monotonous round eccentric nuclei, and the IHC for Ct was positive. Genetic analysis revealed germline mutation in exon 10 of the RET proto-oncogene (NM_020975.4: c.1858T&gt;G, p.C620G). Finally, MEN 2A with recurrent MTC was diagnoses during pregnancy. The other associate diseases were not found (normal urine metanephrines and plasma calcium levels). The Ct level raised highest to 324 pg/ml at 28 weeks of pregnancy and declined to 236 pg/mL a few days after delivery. Within six weeks, the Ct levels raised again (335 and 362 pg/ml at six weeks and three months after delivery).
After giving birth, she underwent neck dissection; The Ct level at one month after surgery was still elevated (85 pg/ml). The CT of the chest, abdomen, and bone scan revealed multiple LN and bone metastasis. She regularly followed up in the oncology clinic and did well until nowadays (two years after delivery). After birth, her son could not pass meconium. Causing underwent exploratory laparotomy with double end ileostomy at day nine of life. The histopathology study from serial bowel biopsy demonstrated aganglionosis of the entire colon, which compatible with Hirschsprung’s disease. Genetic study from colonic tissue and blood confirmed the diagnoses of MEN 2A like his mother. Total thyroidectomy before five years of age and investigate for other associated diseases were planned.
Conclusion: The Ct levels were elevated throughout the pregnancy. Transient declined of Ct levels during delivery and raised within six weeks suggest that pregnancy did not affect the Ct levels. In this report, we want to present the change of Ct levels during pregnancy, emphasize the diagnosis of MTC and MEN2A in pregnant women, which may change the patient’s prognosis. Not only in the patients but also in their families. Clinicians should be aware of the management of these patients.