title: Elevated thyroid-stimulating hormone level in a euthyroid neonate caused by macro thyrotropin-IgG complex.
abstract: Elevated thyroid-stimulating hormone (TSH) was discovered by routine neonatal screening in a newborn with no clinical symptoms. Thyroid function tests were repeated and confirmed a high TSH value but normal total thyroxine (T4) and triiodothyronine (T3). However, the mother also had elevated serum TSH with normal levels of T4 and T3. The results suggested a transmitted maternal interfering factor, and no treatment was started while further investigation was performed. Gel filtration chromatography of serum from both the infant and the mother showed a peak TSH with molecular mass consistent with a TSH-IgG complex (macro-TSH). TSH in the infant decreased to a normal level within 8 months in accordance with a normal rate of elimination of maternal IgG, whereas the TSH level of the mother remained high.
  
  
  CONCLUSIONS
  This case suggests that interfering macro-TSH should be considered in a euthyroid neonate with elevated serum TSH and normal T4 and T3 levels to avoid unnecessary treatment.
authors.affiliation: Department of Pediatrics, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark. mariane.rix@rn.dk
authors.forename: Mariane
authors.initials: M
authors.lastname: Rix
authors.forename: Peter
authors.initials: P
authors.lastname: Laurberg
authors.forename: Christina
authors.initials: C
authors.lastname: Porzig
authors.forename: Søren Risom
authors.initials: SR
authors.lastname: Kristensen
mesh_terms: D000936:Antigen-Antibody Complex / Q000097:blood*; D002850:Chromatography, Gel; D005067:Euthyroid Sick Syndromes / Q000097:blood*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007231:Infant, Newborn; D015997:Neonatal Screening; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine