Abdominal fat distribution and cardiovascular risk factors in hypertensive females

Abstract

The link between abdominal fat distribution and insulin related cardiovascular risk factors in black and white female hypertensives who were on drug treatment for hypertension was investigated with computed tomography scan, sonar, anthropometric measurements and blood testing. Fasting blood samples were tested for: insulin, glucose, triglyceride, apoprotein B, apoprotein A1, total cholesterol, HDL cholesterol, lipoprotein a, uric acid, fibrinogen and plasminogen activity. Albumin and creatinine were measured in urine samples. Black subjects were slightly more obese than their white counterparts as judged from their body mass indexes (34.39±6.60 vs. 32.08±6.77 kg/m2, p<0.187) and they had similar waist to hip ratios (0.80±5.70 vs. 0.79±5.61, p=0.540). Despite this, white subjects had more intra-abdominal fat than black subjects (162. 76±63.97 vs. 131.17±63.89 cm2 , p=0.207) and this difference became more pronounced after excluding the values of six black diabetic subjects (162.76 vs. 107.53±9.10 cm 2, p=0.000) who all had visceral fat areas larger than 177 cm2. Visceral fat areas correlated with fasting glucose (r=0.79), triglyceride (r=0.60) and insulin resistance (r=0.70) in black subjects and with LDL particle size (r=-0.60) triglyceride (r=0.60) and insulin resistance (r=0.60) in white subjects. Hypertriglyceridaemia seems to be the mediator of dyslipidaemia in particular a decrease in HDL cholesterol levels and an increase in the number of small atherogenic LDL particles. This may happen at triglyceride levels considerably lower than 2.3 mmol/l, which is generally accepted as the high-risk cut-off point. Waist to hip ratio did not seem to be a good indicator of visceral fat or cardiovascular risk in the present study and it was concluded that waist circumference or intra-abdominal sonar may be more reliable in this regard. The present study also showed that cardiovascular risk assessment of white females with apparently normal LDL cholesterol levels might be inconclusive without the measurement of apo B. High lipoprotein (a) levels in black females may not be so innocuous as previously thought, especially if it occurs in conjunction with high fibrinogen and high LDL cholesterol levels as seen in some subjects in the present study.


(S. African J. for Research in Sport, Physical Ed. and Recreation: 2002 24 (1):53-76)