title: The biochemical prognostic factors of subclinical hypothyroidism.
abstract: BACKGROUND
  Patients with subclinical hypothyroidism (SHT) are common in clinical practice. However, the clinical significance of SHT, including prognosis, has not been established. Further clarifying SHT will be critical in devising a management plan and treatment guidelines for SHT patients. Thus, the aim of this study was to investigate the prognostic factors of SHT.
  
  
  METHODS
  We reviewed the medical records of Korean patients who visited the endocrinology outpatient clinic of Severance Hospital from January 2008 to September 2012. Newly-diagnosed patients with SHT were selected and reviewed retrospectively. We compared two groups: the SHT maintenance group and the spontaneous improvement group.
  
  
  RESULTS
  The SHT maintenance group and the spontaneous improvement group had initial thyroid-stimulating hormone (TSH) levels that were significantly different (P=0.035). In subanalysis for subjects with TSH levels between 5 to 10 µIU/mL, the spontaneous improvement group showed significantly lower antithyroid peroxidase antibody (anti-TPO-Ab) titer than the SHT maintenance group (P=0.039). Regarding lipid profiles, only triglyceride level, unlike total cholesterol and low density lipoprotein cholesterol, was related to TSH level, which is correlated with the severity of SHT. Diffuse thyroiditis on ultrasonography only contributed to the severity of SHT, not to the prognosis. High sensitivity C-reactive protein and urine iodine excretion, generally regarded as possible prognostic factors, did not show any significant relation with the prognosis and severity of SHT.
  
  
  CONCLUSIONS
  Only initial TSH level was a definite prognostic factor of SHT. TPO-Ab titer was also a helpful prognostic factor for SHT in cases with mildly elevated TSH. Other than TSH and TPO-Ab, we were unable to validate biochemical prognostic factors in this retrospective study for Korean SHT patients.
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Myung Won
authors.initials: MW
authors.lastname: Lee
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Dong Yeob
authors.initials: DY
authors.lastname: Shin
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Kwang Joon
authors.initials: KJ
authors.lastname: Kim
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sena
authors.initials: S
authors.lastname: Hwang
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Eun Jig
authors.initials: EJ
authors.lastname: Lee
keywords: C-reactive protein; Iodine; Lipids; Subclinical hypothyroidism; Thyroid peroxidase antibody; Thyrotropin