serum sterol level blood phytosterol level serum phytosterol level 2014-01-23T17:11:15Z CMO:0002052 The amount of one or more phytosterols in a specified sample of serum, the clear liquid that separates from blood after it has clotted completely, i.e. blood plasma from which fibrinogen has been removed. Phytosterols, which encompass both plant sterols and stanols, comprise a large group of steroid compounds similar to cholesterol which occur in plants and vary only in carbon side chains and/or presence or absence of a double bond. clinical_measurement_ontology jsmith