title: Testosterone and acute stress are associated with fibrinogen and von Willebrand factor in African men: the SABPA study.
abstract: BACKGROUND
  Low testosterone, acute and chronic stress and hypercoagulation are all associated with hypertension and hypertension-related diseases. The interaction between these factors and future risk for coronary artery disease in Africans has not been fully elucidated. In this study, associations of testosterone, acute cardiovascular and coagulation stress responses with fibrinogen and von Willebrand factor in African and Caucasian men in a South African cohort were investigated.
  
  
  METHODS
  Cardiovascular variables were studied by means of beat-to-beat and ambulatory blood pressure monitoring. Fasting serum-, salivary testosterone and citrate coagulation markers were obtained from venous blood samples. Acute mental stress responses were evoked with the Stroop test.
  
  
  RESULTS
  The African group demonstrated a higher cardiovascular risk compared to Caucasian men with elevated blood pressure, low-grade inflammation, chronic hyperglycemia (HbA1c), lower testosterone levels, and elevated von Willebrand factor (VWF) and fibrinogen levels. Blunted testosterone acute mental stress responses were demonstrated in African males. In multiple regression analyses, higher circulating levels of fibrinogen and VWF in Africans were associated with a low T environment (R(2) 0.24-0.28; p≤0.01), but only circulating fibrinogen in Caucasians. Regarding endothelial function, a low testosterone environment and a profile of augmented α-adrenergic acute mental stress responses (diastolic BP, D-dimer and testosterone) were associated with circulating VWF levels in Africans (Adj R(2) 0.24; p<0.05).
  
  
  CONCLUSIONS
  An interdependence between acute mental stress, salivary testosterone, D-dimer and vascular responses existed in African males in their association with circulating VWF but no interdependence of the independent variables occurred with fibrinogen levels.
authors: Hypertension in Africa Research Team (HART), Faculty of Health Sciences, North West University, Potchefstroom, South Africa. Electronic address: nico.malan@nwu.ac.za.
authors: Nicolaas T
authors: NT
authors: Malan
authors: Roland
authors: R
authors: von Känel
authors: Alta E
authors: AE
authors: Schutte
authors: Hugo W
authors: HW
authors: Huisman
authors: Rudolph
authors: R
authors: Schutte
authors: Wayne
authors: W
authors: Smith
authors: Carina M
authors: CM
authors: Mels
authors: Ruan
authors: R
authors: Kruger
authors: Muriel
authors: M
authors: Meiring
authors: Johannes M
authors: JM
authors: van Rooyen
authors: Leoné
authors: L
authors: Malan
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D044383:Black People; D018660:Blood Pressure Monitoring, Ambulatory; D005340:Fibrinogen / Q000378:metabolism*; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000209:etiology / Q000503:physiopathology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D013315:Stress, Psychological / Q000097:blood* / Q000150:complications / Q000208:ethnology; D013739:Testosterone / Q000097:blood*; D044465:White People; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D014841:von Willebrand Factor; D013739:Testosterone; D005340:Fibrinogen
keywords: Acute stress; D-dimer; Fibrinogen; Haemostasis; Testosterone; von Willebrand factor