The center of analytic interest in both normal and pathologic metabolism, as The Journal has frequently stated, is shifting from the urine to the blood. A decade ago the withdrawal of a few cubic centimeters of blood from the vein of a human patient for purely diagnostic purposes was a somewhat formidable and certainly a decidedly uncommon procedure; today the collection of blood samples in man is a routine practice. Pathology, bacteriology and physiologic chemistry all have benefited by the accumulating data derived from such technical analyses of the blood. Information has been obtained of unquestioned importance in the domains of therapy and prognosis as well as diagnosis. It is no longer bewildering to an up-to-date physician to discuss the content of sugar, or uric acid, or nonprotein nitrogen in the blood, any more than it was either to consider comparable statistics about the urine a few years ago or to take guidance from a blood count or hemoglobin estimation.
The Lipoids (“Fats”) of Human Blood. JAMA. 2016;316(6):669. doi:10.1001/jama.2015.17097