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Sex hormones associated with subclinical kidney damage and atherosclerosis in South African men: the SABPA study

Malan, Nico T.a; Hamer, Marka,b; Lambert, Gavin W.c; Schutte, Aletta E.a; Huisman, Hugo W.a; Van Rooyen, Johannes M.a; Mels, Catharina M.a; Smith, Waynea; Fourie, Carla M.T.a; Schutte, Rudolpha; Kruger, Ruana; Malan, Leonéa

doi: 10.1097/HJH.0b013e3283599bb5
ORIGINAL PAPERS: Kidney
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Background: Hypertension and increased blood glucose are associated with subclinical kidney damage, atherosclerosis and with low testosterone values. Low testosterone in men is often accompanied by increased levels of estradiol.

Objectives and methods: In this study, the association between estradiol, subclinical kidney damage and atherosclerosis in African and white men in a South African cohort was investigated. Cardiovascular variables were studied by means of B-mode ultrasound and ambulatory blood pressure (BP) monitoring. The sex hormones and other biochemical values were measured from fasting venous blood and overnight urine samples. The ethnic groups were stratified into low and high testosterone groups by means of median split.

Results: The low testosterone African group demonstrated a higher cardiovascular risk compared with the low testosterone white men with 91% being hypertensive and having increased albumin-to-creatinine ratio (ACR), left carotid intima–media thickness (L-CIMTf) and estradiol-to-testosterone ratio. In the low-testosterone African men, estradiol explained 33% of the variance in ACR, whereas the estradiol-to-testosterone ratio explained 22% of the variance in L-CIMTf, respectively. Estradiol-to-testosterone ratio was positively associated with ACR in the low testosterone whites.

Conclusion: We conclude that increased levels of estradiol may play a role in the development of subclinical kidney damage in both African and white men as well as atherosclerosis in low-testosterone African men.

aHypertension in Africa Research Team (HART), School for Physiology, Nutrition and Consumer Sciences, North West University, Potchefstroom, South Africa

bDepartment of Epidemiology and Public Health, University College of London, London, UK

cHuman Neurotransmitters Laboratory, Baker IDI Heart and Diabetes Institute and Faculty of Medicine, Nursing & Health Sciences, Monash University, Melbourne, Australia

Correspondence to Professor Nico Malan, DSc, Hypertension of Africa Research Team (HART), School for Physiology, Nutrition and Consumer Sciences, North-West University, Potchefstroom Campus, Private Bag X6001, Hoffman Street, Potchefstroom, 2520, South Africa. Tel: +27 18 299 2438; fax: +27 18 2991053; e-mail: nico.malan@nwu.ac.za

Abbreviations: γ-GT, gamma-glutamyl transferase; ABPM, ambulatory blood pressure monitoring; ACR, albumin-to-creatine ratio; CRP, C-reactive protein; HbA1C, glycated haemoglobin; SHBG testosterone, serum hormone binding globulin testosterone

Received 30 April, 2012

Revised 30 July, 2012

Accepted 22 August, 2012

© 2012 Lippincott Williams & Wilkins, Inc.