Cholesterol, hormones, salt, glucose can all be measured from blood. is it possible to measure level of hydration via blood? 2 c if i have enough h2o

Hydration level: When your body is "dry", the concentration of chemicals and cells get higher. Each volume of blood has more concentrated numbers of red cells and white cells. The concentration of electrolytes ( sodium, chloride, potassiums...) all get higher. The acidity of the body fluids can change drastically depending on the degree of dehydratation. Death can occur when chemicals get too much out of range...

Inferred: Sate of hydration can be inferred from blood levels of protein, hemoglobin, sodium etc, by comparing with earlier levels. Measurement of serum osmolality provides an independent measure of the solute content of blood.