Schommeling van het serumcholesterolgehalte bij één persoon: wat is de werkelijke waarde en wanneer is er sprake van een significante verandering?
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04-08-1992
I.J.M. Hendriksen, P.D. Bezemer, G.J.M. Boerma en U. Zuiderveld

Intra-individual biological variation of the serum cholesterol and the consequences for screening and follow-up.

- The blood cholesterol level is not constant over time. Changing values may be found when rechecking high values, especially in patients on a diet or receiving medication. Repeated measurements are necessary. It will then be possible to estimate the ‘true mean value’. This is the theoretical average of a large number of measurements taken from one person.

The study concentrated on the intra-individual variation of the serum cholesterol and the consequences for screening and follow-up. For this purpose, during a period of four weeks, cholesterol levels were measured 12 times in 33 men aged 25-40. The mean coefficient of variation was 5.7, with wide differences between participants, ranging from 2.9 to 9.8. The position of the ‘true mean value’ was estimated (with 90 confidence), after 1 resp. 3 determinations.

These findings have consequences for the classification of subjects in the different risk categories as defined in the Dutch Cholesterol Consensus. It is also possible to determine if, after a period of intervention, there is a significant decline in the cholesterol level. Roughly, a decline of 10-12 indicates a significant difference.