Cholesterol is a major component of all biological membranes. In cell cultures, cholesterol can be produced by the cells, nevertheless, a certain level of cholesterol in the culture medium is advantageous for cell growth and viability. With a controlled cholesterol concentration, cells grow faster and to higher density. For control of culture media and for monitoring in a culture process, the cholesterol concentration can be determined on a Cedex Bio or Cedex Bio HT Analyzer with high reliability and convenience.