Systematic investigations of endogenous cortisol and cortisone in nails by LC-MS/MS and correlation to hair

Abstract

Hair samples are increasingly used for measuring the long-term stress mediator cortisol. However, hair is not always available and nails (finger or toe), as a keratinized matrix, may be an alternative to hair. In order to measure cortisol and cortisone in the nail matrix, an LC-MS/MS method has been developed and validated using C-labeled surrogate analytes. Both analytes were measured in ESI negative mode as formic acid adducts. Different sample preparation techniques were assessed, and single-step extraction in methanol was established for determination of cortisone and cortisol in the nail matrix. The method was successfully validated with limits of detection (LOD) and limits of quantification (LOQ) of 0.5 and 1.0 pg/mg for cortisol and cortisone, respectively. The calibration curve was linear up to a concentration of 500 pg/mg. Recovery was good for both analytes and showed values over 50%. Matrix effects with ion suppression occurred for both substances but could be corrected by the use of internal standard. Accuracy and precision were in the accepted range of ± 20% for both substances. The method was successfully applied to determine cortisol and cortisone concentrations in authentic nail samples. Cortisol and cortisone concentrations varied significantly among different fingernails, being highest in the little fingernails and lowest in the thumbnails. It could be shown that even in only 1 mg nail sample cortisol and cortisone can be reliably quantified. No correlation between hair and nail cortisol and cortisone concentrations could be found. Furthermore, cortisol and cortisone concentrations were significantly higher in hair. Graphical abstract.

Endocannabinoid and steroid analysis in infant and adult nails by LC–MS/MS

“…Yet, compared to hair analyses, the concentrations of endogenous analytes in nails are lower. This is also in accordance with other findings [ 23 , 26 ]. The difference in analyte concentrations in nail and hair samples might be explained by several factors, such as melanin binding, physicochemical properties of the incorporated substances, incorporation mechanisms, and surfaces of the two different matrices.…”

“…The following parameters were evaluated: response factor (for the surrogate analytes), selectivity, linearity, limit of quantification (LOQ), accuracy, precision, matrix effect, recovery, robustness, and autosampler stability. For validation, the approach of using a surrogate analyte was applied as described before [16,22,25,26]. Four deuterated standards were chosen as surrogate analytes for the eCBs (D 4 -AEA, D 5 -2-AG, D 4 -OEA, and D 4 -PEA), and five stable isotope-labeled standards were chosen for the steroid hormones ( 13 C 3 -cortisol, 13 C 3 -cortisone, 13 C 3 -androstenedione, 13 C 3 -progesterone, 13 C 3 -testosterone).…”

Assessment of prenatal stress‐related cortisol exposure: focus on cortisol accumulation in hair and nails

“…Similarly, some investigators have reported correlations between nail CORT and either hair or salivary CORT (Frugé et al., 2018; Izawa et al., 2015, 2019), but no significant correlation between nail and hair CORT was reported by Binz et al. (2018). Much more information is obviously needed regarding the validity of nail CORT as a biomarker of chronic stress.…”

“…Nail CORT was found to be positively correlated with perceived stress in a recent study of Chinese medical students (Wu, Zhou, Xue, Xu, & Liu, 2018) but not in the study of African-American high school students (Doan et al, 2018). Similarly, some investigators have reported correlations between nail CORT and either hair or salivary CORT (Frugé et al, 2018;Izawa et al, 2015Izawa et al, , 2019, but no significant correlation between nail and hair CORT was reported by Binz et al (2018). Much more information is obviously needed regarding the validity of nail CORT as a biomarker of chronic stress.…”

Novel method of measuring chronic stress for preterm infants: Skin cortisol

“…To date the serum alterative biological sources that measure acute stress include saliva and urine (Moore, 2015;Vittner et al, 2017). Biological sources of cortisol that measure chronic stress include hair and nail sampling (Bates et al, 2017;Binz et al, 2018;Groer et al, 2014). Pragmatic factors that complicate collection of these samples in preterm infants include very limited hair (Stalder et al, 2017) and nail growth and saliva sample collection itself may be noxious due to limited volume (Maas et al, 2014;Mitchell et al, 2012).…”