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Absence of diurnal variation of C-reactive protein concentrations in healthy human subjectsBACKGROUND: The concentration of C-reactive protein (CRP) in otherwise healthy subjects has been shown to predict future risk of myocardial infarction and stroke. CRP is synthesized by the liver in response to interleukin-6, the serum concentration of which is subject to diurnal variation. METHODS: To examine the existence of a time-of-day effect for baseline CRP values, we determined CRP concentrations in hourly blood samples drawn from healthy subjects (10 males, 3 females; age range, 21-35 years) during a baseline day in a controlled environment (8 h of nighttime sleep). RESULTS: Overall CRP concentrations were low, with only three subjects having CRP concentrations >2 mg/L. Comparison of raw data showed stability of CRP concentrations throughout the 24 h studied. When compared with cutoff values of CRP quintile derived from population-based studies, misclassification of greater than one quintile did not occur as a result of diurnal variation in any of the subjects studied. Nonparametric ANOVA comparing different time points showed no significant differences for both raw and z-transformed data. Analysis for rhythmic diurnal variation using a method fitting a cosine curve to the group data was negative. CONCLUSIONS: Our data show that baseline CRP concentrations are not subject to time-of-day variation and thus help to explain why CRP concentrations are a better predictor of vascular risk than interleukin-6. Determination of CRP for cardiovascular risk prediction may be performed without concern for diurnal variation.
Document ID
20040112533
Document Type
Reprint (Version printed in journal)
Authors
Meier-Ewert, H. K.
(Lahey Clinic Medical Center 41 Mall Rd., Burlington, MA 01805, United States)
Ridker, P. M.
Rifai, N.
Price, N.
Dinges, D. F.
Mullington, J. M.
Date Acquired
August 21, 2013
Publication Date
March 1, 2001
Publication Information
Publication: Clinical chemistry
Volume: 47
Issue: 3
ISSN: 0009-9147
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NR-04281
CONTRACT_GRANT: MH-48300
CONTRACT_GRANT: R-00040
CONTRACT_GRANT: HL-58755
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Regulatory Physiology
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