QNS is a clinical laboratory abbreviation for Quantity Not Sufficient. This indicates that either 1.) There is not enough specimen for the lab tests ordered to be performed. 2.) In the case of Vacutainers or other tubes with pre-added anticoagulant, the amount of blood invacuated into the tube at the time of phlebotomy was insufficient to attain t... Found on http://en.wikipedia.org/wiki/QNS