Quantification of sphingomyelin (d18:1/25:0, d19:0/24:1, d20:1/23:0, d19:1/24:0) in a sample. The trait is Experimental Factor Ontology term EFO_0803578 (sphingomyelin (d18:1/25:0, d19:0/24:1, d20:1/23:0, d19:1/24:0) measurement).