This patient is presenting with congenital hypothyroidism (CH), which presents on lab findings as decreased total & free T4 with increased TSH.
CH results from a lack of maternal iodine intake during pregnancy, or from a defect in T4 synthesis or thyroid formation. Severe mental retardation can result if this condition is not treated, as T4 is very crucial for normal brain development during the first two years of life. In addition, untreated CH increases the risk of mitral regurgitation. Infants affected by CH typically present with severe mental retardation, increased weight, short stature, coarse facial features, macroglossia, umbilical hernia, myxedema, hypotonia, mild jaundice, constipation, or poor feeding. Lab results will reveal a decreased total and free T4 and elevated TSH serum levels. Treatment usually consists of levothyroxine replacement.
Rogers reviews the different forms of thyroid disease that may occur in children. He states that the crucial laboratory values for determining thyroid status are free thyroxine and TSH. In addition, measuring thyroid antibody titers may be helpful in further defining the exact etiology of hypothyroidism.
Rastogi and LaFranchi review CH. They state that the incidence of CH is between 1:2,000-4,000 newborns. Newborn symptoms may be subtle due to the placental transfer of maternal thyroid hormone during pregnancy. Congenital hypothyroidism is divided into three categories: primary, secondary, and other. Primary causes include thyroid dysgenesis (85%) and problems with thyroid hormone synthesis (10-15%). Secondary causes include deficiencies in TSH. If levothyroxine treatment is initiated within 30 days after birth, a child with CH will typically progress with normal brain development.
Figure A demonstrates macroglossia and myxedema in a neonate with CH. Figure B demonstrates an umbilical hernia and abdominal distension in a neonate with CH.
Answer 2: Lab findings in hyperthyroidism increase in total and free T4 and decreased TSH serum levels.
Answer 3: Lab findings in Hashimoto's disease include the presence of inhibitory anti-TSH receptor antibodies.
Answer 4: Lab findings in Grave's disease include the presence of stimulatory TSH receptor antibodies.
Answer 5: Lab findings in sick euthyroid syndrome include a decrease in total T4 and T3, normal TSH, and increased reverse T3 serum levels.
Rogers DG. Thyroid disease in children. Am Fam Physician. 1994 Aug;50(2):344-50. Review.
PMID:8042569 (Link to Abstract)
Rastogi MV, LaFranchi SH. Congenital hypothyroidism. Orphanet J Rare Dis. 2010 Jun 10;5:17. doi: 10.1186/1750-1172-5-17. Review.
PMID:20537182 (Link to Abstract)