Serum and thyroid tissue lipids in patients with thyroid tumors in euthyroidism.

Plasma lipids of 24 euthyroid subjects with thyroid adenoma and non-toxic primary differentiated thyroid carcinoma (papillary and follicular types) were assessed and compared with a similar investigation conducted on 20 normal subjects. A parallel study with thyroid tumor tissues examined the lipid changes which occurred in the same group of patients. These were compared with the picture seen in 5 normal thyroids. The investigations examined the changes in total lipids; total, free and esterified cholesterol; total phospholipids; lecithin; cephalin and sphingomyelin; triglycerides and free fatty acids in both serum and thyroid tissue. Compared with normal subjects, the serum lipids were almost identical except for the concentration of free fatty acids which showed significantly lower values in the group with neoplastic changes. Tissue analysis of the cancerous thyroid however revealed a marked rise in virtually all lipid fractions but the cholesterol seemed to dominate the picture. The differential studies of total phospholipids for thyroid tissue membrane lipids further revealed a significant increase in the lecithin and sphingomyelin components of total phospholipids as well as the esterified cholesterol fraction in thyroid carcinoma. The changes in thyrophospholipids were more marked in females normal thyroids than males. An attempt has been made through evaluation of the results derived from differential lipid studies to elucidate the role of some of the various fractions determined and the possible effect of the changes described on thyroid hormone metabolism.