Altered metabolism of folates and lipids in hyperthyroid and hypothyroid rats.

Effect of excess folate on the metabolism of folate and plasma lipids in thyroid stressed animals was studied. Administration of excess dietary folate to hyperthyroid rats did not affect the decreased in vivo histidine oxidation in these animals, but it increased the hepatic tetrahydrofolate content. Hypothyroid rats had higher plasma total cholesterol (TC), high density lipoprotein cholesterol (HDLC) and trigylcerides (TG) with no change in post heparin lipolytic activity (PHLA). In hyperthyroidism both TC and HDLC were decreased in plasma and PHLA levels were elevated. On administration of excess dietary folate to hyperthyroid rats HDLC levels were not altered but PHLA and TC levels became near normal, while TG levels remained elevated.