Concentrations of 27 commonly estimated serum constituents were measured in blood sampled from 20 apparently healthy volunteers at 0830, 1230, and 1630 hours on each of four days, at weekly intervals. Time-dependent statistically significant (p less than or equal to 0.01) variation was observed in 12 of the constituents. The 15 constituents that showed no statistically significant diurnal varia...
