So, basically, withholding information is not the same thing as lying, but depending on the situation, you will have to decide whether it is better to withhold the information or not.
HCH may refer to: Hampton Court House, an independent school in Surrey, UK. Hexachlorocyclohexane, a group of chemical compounds. Holmes Chapel railway station (National Rail station code), in Cheshire, England.
The MCH is a calculated value derived from the measurement of hemoglobin and the red cell count. (The hemoglobin value is the amount of hemoglobin in a volume of blood while the red cell count is the number of red blood cells in a volume of blood.) It is a standard part of the complete blood count.