The amount of a NADH dehydrogenase [ubiquinone] iron-sulfur protein 4, mitochondrial when measured in blood serum. The trait is Ontology of Biological Attributes term OBA_2042546 (level of NADH dehydrogenase [ubiquinone] iron-sulfur protein 4, mitochondrial in blood serum). Also known as: blood serum NADH dehydrogenase [ubiquinone] iron-sulfur protein 4, mitochondrial amount.