title: Assessment of serum apelin and lipocalin-2 levels in patients with subclinical hypothyroidism.
abstract: OBJECTIVE
  Subclinical hypothyroidism is the precursor to hypothyroidism because it has a tendency to transform into hypothyroidism. Subclinical hypothyroidism is considered one of the risk factors causing metabolic syndrome. Metabolic syndrome can be characterized by plasma levels of apelin and lipocalin-2, both released from adipocytes. In the present study, we aimed to measure serum apelin and lipocalin-2 levels of patients with subclinical hypothyroidism and compare them with serum apelin and lipocalin-2 levels from healthy individuals.
  
  
  METHODS
  This was a cross-sectional study. A total of 80 subjects were enrolled in the study and divided into two groups: Group A included 39 patients (females, n=34) diagnosed with subclinical hypothyroidism, and Group B (the control group) comprised 41 healthy volunteers (females, n=38). Serum samples were obtained from each participant for the measurement of apelin and lipocalin-2. These were then stored at minus 80°C until the time of analysis, when serum apelin and lipocalin-2 levels of the two groups were compared.
  
  
  RESULTS
  Patients with subclinical hypothyroidism (Group A and Group B subjects [healthy controls]) were comparable with respect to gender, age, and body mass index (BMI) (P=0.412, P=0.863, and P=0.269, respectively), nor was there a statistically significant difference between groups in terms of apelin and lipocalin-2 levels (P=0.87, and P=0.67, respectively). Apelin levels showed a positive and significant correlation with BMI (P=0.034). Serum lipocalin-2 levels showed significant positive correlations with BMI and creatinine levels (P=0.002, and P=0.025, respectively).
  
  
  CONCLUSIONS
  In the present study, no significant difference of serum apelin and lipocalin-2 levels was observed between patients with subclinical hypothyroidism and healthy control subjects. Positive correlations were found, however, between serum apelin level and BMI as well as between serum lipocalin-2 and BMI and creatinine levels.
authors.affiliation: Faculty of medicine, Bezmialem Vakif university, internal medicine clinic, 34093 Fatih, Istanbul, Turkey. Electronic address: drmehmetzorlu@mynet.com.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Zorlu
authors.affiliation: Faculty of medicine, Bezmialem Vakif university, internal medicine clinic, 34093 Fatih, Istanbul, Turkey. Electronic address: dr_kiskac@mynet.com.
authors.forename: Muharrem
authors.initials: M
authors.lastname: Kiskac
authors.affiliation: Faculty of medicine, Bezmialem Vakif university, internal medicine clinic, 34093 Fatih, Istanbul, Turkey. Electronic address: ckaratoprak@hotmail.com.
authors.forename: Cumali
authors.initials: C
authors.lastname: Karatoprak
authors.affiliation: Department of medical biochemistry clinic, faculty of medicine, Bezmialem Vakif University, 34093 Fatih, Istanbul, Turkey. Electronic address: sdkakesgin@gmail.com.
authors.forename: Sidika
authors.initials: S
authors.lastname: Kesgin
authors.affiliation: Faculty of medicine, Bezmialem Vakif university, internal medicine clinic, 34093 Fatih, Istanbul, Turkey. Electronic address: drcakirca@yahoo.de.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Cakirca
authors.affiliation: Faculty of medicine, Bezmialem Vakif university, internal medicine clinic, 34093 Fatih, Istanbul, Turkey. Electronic address: kemalyildiz571@gmail.com.
authors.forename: Kemal
authors.initials: K
authors.lastname: Yildiz
authors.affiliation: Family health care center, 53100 Rize, Turkey. Electronic address: drcuneytardic@hotmail.com.
authors.forename: Cuneyt
authors.initials: C
authors.lastname: Ardic
authors.affiliation: Faculty of medicine, Bezmialem Vakif university, internal medicine clinic, 34093 Fatih, Istanbul, Turkey. Electronic address: malicikrikcioglu@yahoo.com.
authors.forename: Mehmet Ali
authors.initials: MA
authors.lastname: Cikrikcioglu
authors.affiliation: Faculty of medicine, Bezmialem Vakif university, internal medicine clinic, 34093 Fatih, Istanbul, Turkey. Electronic address: rehaerkoc@hotmail.com.
authors.forename: Reha
authors.initials: R
authors.lastname: Erkoc
mesh_terms: D000209:Acute-Phase Proteins; D000328:Adult; D000073861:Apelin; D058070:Asymptomatic Diseases; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000150:complications; D007328:Insulin / Q000097:blood; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008055:Lipids / Q000097:blood; D000071068:Lipocalin-2; D054834:Lipocalins / Q000097:blood*; D008297:Male; D024821:Metabolic Syndrome / Q000209:etiology; D050177:Overweight / Q000097:blood; D011518:Proto-Oncogene Proteins / Q000097:blood*; D013963:Thyroid Hormones / Q000097:blood; D013972:Thyrotropin / Q000097:blood
chemical_list: C115436:APLN protein, human; D000209:Acute-Phase Proteins; D000073861:Apelin; D001786:Blood Glucose; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; C489506:LCN2 protein, human; D008055:Lipids; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D013963:Thyroid Hormones; D013972:Thyrotropin; D003404:Creatinine