Urinary free cortisol: An intermediate phenotype and a potential genetic marker for a salt-resistant subset of essential hypertension

Bindu Chamarthi, Nikheel S. Kolatkar, Steven Hunt, Jonathan S. Williams, Ellen W. Seely, Nancy J. Brown, Laine J. Murphey, Xavier Jeunemaitre, Gordon H. Williams

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Abstract

Context: Emerging evidence suggests a role for cortisol in essential hypertension, and preliminary reports indicate that urinary free cortisol (UFC) may be an intermediate phenotype. Objectives: The objectives of this study were: 1) confirm bimodality of UFC, 2) assess whether UFC variations aggregate in hypertensive families, and 3) compare low-mode and high-mode UFC groups for distinguishing features. Subjects/Setting: Subjects included 390 hypertensives and 166 normotensives from the general community. Design/Interventions: Subjects had blood pressure and laboratory measurements on high- and low-salt diets. Familial aggregation was evaluated in 250 hypertensive siblings from 117 families. Results: Hypertensives had higher UFC than normotensives (P < 0.001) and bimodal distribution of UFC (P < 0.0001). Analyses were controlled for gender and dietary sodium, which are confounding determinants of UFC. Mean low-mode UFC (33.8 ± 10.6 μg per 24 h) was similar to that of normotensives. The high mode, comprising 31.3% of hypertensives, had less change in mean arterial pressure between diets than the low mode (P = 0.01) without any other significant differences. Observed proportions of concordance and discordance for UFC mode differed significantly from that expected (P < 0.001). Observed concordance for the high mode was twice that expected, whereas for the low mode, it was similar to that expected by chance. Family membership explained a significant proportion of variance in UFC classification (P = 0.027). UFC mode of one sibling was a significant predictor of the UFC mode of the other sibling [odds ratio 6.6, 95% confidence interval (2.4 -18.0), P < 0.001]. Conclusion: High-mode UFC is an intermediate phenotype of hypertension associated with salt resistance and a strong familial component supporting heritability.

Original languageEnglish
Pages (from-to)1340-1346
Number of pages7
JournalJournal of Clinical Endocrinology and Metabolism
Volume92
Issue number4
DOIs
Publication statusPublished - Apr 2007
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology, Diabetes and Metabolism

Cite this

Chamarthi, B., Kolatkar, N. S., Hunt, S., Williams, J. S., Seely, E. W., Brown, N. J., Murphey, L. J., Jeunemaitre, X., & Williams, G. H. (2007). Urinary free cortisol: An intermediate phenotype and a potential genetic marker for a salt-resistant subset of essential hypertension. Journal of Clinical Endocrinology and Metabolism, 92(4), 1340-1346. https://doi.org/10.1210/jc.2006-2093