An Unusual and Early Presentation of Congenital Hypothyroidism

Introduction: Congenital hypothyroidism (CH) has a large spectrum of clinical manifestations, which include failure to thrive, lethargy, feeding problems, abdominal distension, or constipation. However, the majority of newborns have few, unspecific, or no early clinical manifestations of hypothyroidism; therefore, in developed countries, early diagnosis is achieved through the universal newborn screening test. We report an atypical presentation at birth of primary CH with abdominal distension and ascites associated with hypoglycemia and hyponatremia.

Materials and Methods: A male neonate was born at 41 weeks of gestation via vacuum extraction. During the third trimester, maternal hypothyroidism was diagnosed; antibodies against thyroid-stimulating hormone (TSH) receptor, antithyroid peroxidase, and antithyroglobulin were negative. Approximately 2 hours after birth, he started moaning and hypoglycemia was detected, initially treated with oral 10% dextrose and infant formula. When he was admitted into the neonatology unit, due to the maintenance of hypoglycemia, marked abdominal distension was observed and serum hyponatremia (122 mEq/L) was detected; the abdominal radiography suggested intestinal subocclusion. With intravenous correction, hyponatremia was gradually corrected in 48 hours. The patient was then referred to a neonatal intensive care unit in a tertiary hospital. Abdominal Doppler ultrasound showed hepatomegaly and pure fluid collections in the subhepatic and perisplenic spaces, parietocolic gutter evocative of ascites, along with bowel filled with liquid and gaseous contents, without parietal thickening or signs of intestinal pneumatosis. At 48 hours after birth, unmeasurable high TSH (>100 µIU/mL [0.73–4.77]) and low-free thyroxine (0.46 ng/dL [0.68–2.53]) were detected. CH was suspected and after confirmation of laboratory values, intravenous levothyroxine 8 µg/kg/d was started. Antithyroid peroxidase and antithyroglobulin autoantibodies were negatives; the universal newborn screening test was positive for CH. At 11 days after birth, while fed with both mother’s milk and infant’s formula, abdominal discomfort was noted and feces with blood were passed. Cow’s milk protein intolerance was suspected and extensively hydrolyzed formula was started with attenuation of symptoms; subsequent provocation trial was positive. A delayed in the acquisition of oral feeding skills was observed, in spite of normal levels of thyroid hormones, postponing the return to the local neonatal unit.

Conclusion: This case highlights CH as a cause of neonatal intestinal occlusion. Hyponatremia and hypoglycemia are rare clinical manifestations of primary CH, notwithstanding, clinicians should be aware of screening thyroid function, in presence of persistent intestinal dysmotility. Cow’s milk protein intolerance can interfere with intestinal absorption of levothyroxine and may hinder the management of CH.

Keywords: congenital hypothyroidism; intestinal subocclusion; hyponatremia; hypoglycemia

Conflict of Interest: None declared.