Hair as a Novel Long Term Biological Indicator for Assessing the Human Na and K Nutritional Status

How much sodium (Na) and potassium (K) should be in the human diet so that it would not be accompained with cardiovascular events is a perenial epidemiology challenge. Urinary Na and K are the standard short term biological indicators of Na and K dietary exposure. In this study we have assessed Na and K population status from frequency distribution properties of their concentration in the hair as a long term biological indicator. The study was conducted according to the Basic Principles of the Declaration of Helsinki. Na and K were analyzed in 1072 hair samples of healthy adult subjects (733 [female]and 339 [male]) with ICP MS and ICP EMS, respectively. The median values (µg•g ‐1 ) were Na ([female]254 and [male]371) and K ([female]74.3 and [male]143), respectively; the log transformed data were analyzed with the method of median derivatives (Thyroid 2014;24:1018‐1026). The observed sigmoid curves had a linear range: Na ([female] 55,6 ‐ 1307, [male] 84.0 – 1450), K ([female] 18.9 – 467, [male] 25.8 – 1079). This linear and adequate segment of hair saturation with Na and K is itself an exponential 3‐compartment Michaelis‐Menton kinetic model, where the respective sparse, true, and ample adequate Na and K hair deposition may be identified. We propose that the human true adequate Na and/or K hair concentrations should be: Na ([female] 420 – 563, [male] 790 ‐ 975), K ([female] 142 – 283, [male] 286 ‐ 588).This is the first personalized human Na and K assessment based on the results of their intermediary metabolic response.