title: Subclinical hypothyroidism and cardiovascular risk.
abstract: BACKGROUND
  Subclinical hypothyroidism (SCH) has been suggested to be associated with increased cardiovascular risk by different mechanisms. Several cardiovascular risk factors have been analysed, but yielded controversial results.
  
  
  OBJECTIVE
  We aimed to analyse whether there are differences in several cardiovascular risk markers, such as lipids, inflammatory parameters: plasma viscosity (PV), fibrinogen and C reactive protein (CRP); homocysteine (Hcy) and red blood cell distribution width (RDW), when comparing SCH and controls. We also analysed which of these parameters predict SCH risk and constitute independent markers.
  
  
  METHODS
  We determined PV in a Fresenius capillary plasma viscosimeter, Hcy by a chemiluminiscent enzyme immunoassay, and biochemical and haematological parameters by conventional laboratory methods in 58 SCH outpatients and 58 controls matched for age and gender.
  
  
  RESULTS
  SCH patients did not show statistical differences for glucose, lipids or leucocytes (p > 0.05). However, patients showed a higher prevalence for use of hypolipidaemic drugs, body mass index (BMI), thyroid stimulating hormone (TSH), PV, CRP, fibrinogen, Hcy and RDW (p < 0.05). RDW correlated with inflammation parameters: PV (r = 0.331, p < 0.05), fibrinogen (r = 0.424, p < 0.05), CRP (r = 0.433, p < 0.01) and leucocytes (r = 0.613, p < 0.01). None of the cardiovascular markers correlated with the TSH levels (p > 0.05) In the unadjusted logistic regression analyses, BMI ≥28 kg/m2, RDW ≥14%, Hcy ≥12 μm/L, fibrinogen ≥400 mg/dL and MCV ≤88 fL increased SCH risk, but only RDW ≥14% and fibrinogen ≥400 mg/dL independently increased this risk in the adjusted logistic regression analyses (OR = 4.68, 95% CI 1.20-18.30 P = 0.026; OR = 3.48, 95% CI 1.08-11.23 P = 0.037).
  
  
  CONCLUSIONS
  SCH patients show a higher cardiovascular risk, characterised by increased PV, fibrinogen, Hcy and RDW. However, only fibrinogen ≥400 mg/dL and RDW ≥14% are independent predictors of SCH.
authors.affiliation: Hemorheology and Haemostasis Unit, Service of Clinical Pathology, La Fe University Hospital, Valencia, Spain.
authors.forename: Amparo
authors.initials: A
authors.lastname: Vayá
authors.affiliation: Hemorheology and Haemostasis Unit, Service of Clinical Pathology, La Fe University Hospital, Valencia, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Giménez
authors.affiliation: Hemorheology and Haemostasis Unit, Service of Clinical Pathology, La Fe University Hospital, Valencia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Sarnago
authors.affiliation: Hemorheology and Haemostasis Unit, Service of Clinical Pathology, La Fe University Hospital, Valencia, Spain.
authors.forename: Amparo
authors.initials: A
authors.lastname: Alba
authors.affiliation: Endocrinology Service, Dr. Peset University Hospital, Valencia, Spain.
authors.forename: Olaya
authors.initials: O
authors.lastname: Rubio
authors.affiliation: Endocrinology Service, Dr. Peset University Hospital, Valencia, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Hernández-Mijares
authors.affiliation: Endocrinology Service, La Fe University Hospital, Valencia, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Cámara
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000150:complications* / Q000175:diagnosis*; D016022:Case-Control Studies; D004912:Erythrocytes / Q000166:cytology; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D064368:Healthy Volunteers; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000175:diagnosis*; D007124:Immunoenzyme Techniques; D007249:Inflammation / Q000097:blood; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012307:Risk Factors; D013972:Thyrotropin / Q000097:blood; D014783:Viscosity
chemical_list: D006710:Homocysteine; D005340:Fibrinogen; D013972:Thyrotropin; D002097:C-Reactive Protein
keywords: Subclinical hypothyroidism; cardiovascular risk; fibrinogen; homocysteine; plasma viscosity; red blood cell distribution width