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A method is described for a temperature-controlled ultrafiltration procedure to measure free cortisol in serum. A special thermometer with a sensor was developed, measuring the temperature directly in the ultrafiltration device. The sensor is screwed on the axis of the centrifuge rotor, and the centrifuge is placed in a temperature-controlled box so that the temperature of the sample is kept at 37 degrees C +/- 0.1 degrees C. The overall CV of the free cortisol assay ranges from 2.2% to 11.4%, of which the ultrafiltration contributes only 2.2-3.6%. Increasing amounts of cortisol-binding protein, as found in women using estrogen-containing oral contraceptives, have minor but significant effects on the free cortisol concentrations in serum. Serum free cortisol concentrations in a reference population (n = 114; central 95 percentiles) were 12-43 nmol/L (4-9.5% of total cortisol); in the group of the oral-contraceptive users (n = 27), the reference interval was 11-53 nmol/L (1.5-4.5%).
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
April 1987,
Clinical chemistry,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
March 1979,
Clinica chimica acta; international journal of clinical chemistry,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
January 1991,
Clinical chemistry,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
August 1980,
Steroids,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
December 1992,
Clinical chemistry,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
January 2007,
Clinical chemistry and laboratory medicine,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
February 1984,
Clinical chemistry,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
January 1988,
Clinical and experimental hypertension. Part A, Theory and practice,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
June 1992,
Journal of pharmaceutical and biomedical analysis,
E G Lentjes, and
F Romijn, and
R J Maassen, and
L de Graaf, and
P Gautier, and
A J Moolenaar
January 1984,
Therapeutic drug monitoring,
