[1] Univ Cape Town, Groote Schuur Hosp, Div Chem Pathol, Cape Town, South Africa
[2] Univ Cape Town, Groote Schuur Hosp, Dept Med, Div Lipidol, Cape Town, South Africa
[3] Natl Hlth Lab Serv, Cape Town, South Africa
[4] Vrije Univ Amsterdam Med Ctr, Dept Internal Med, Amsterdam, Netherlands
[5] MC Slotervaart, Dept Internal Med, Amsterdam, Netherlands