Normalization of low-density lipoprotein levels and disappearance of xanthomas during pregnancy in a woman with heterozygous familial hypercholesterolemia.

Serum lipids and lipoproteins were studied prior to conception, during pregnancy, and after delivery in a woman heterozygous for familial hypercholesterolemia. Prior to conception, serum and low-density lipoprotein (LDL) cholesterol levels were 613 and 528 mg/dL, respectively. At 37-week gestation, serum and LDL cholesterols decreased to the normal levels, 226 and 90 mg/dL, respectively. At two-week postpartum serum and LDL cholesterols returned to the preconception levels, 547 and 427 mg/dL, respectively. At delivery her cutaneous xanthomas almost disappeared. The patient was challenged by ethinyl estradiol of 120 micrograms/d for two months, as a result serum cholesterol decreased from 565 to 385 mg/dL, and LDL cholesterol fell from 460 to 208 mg/dL. During her second pregnancy, serum and LDL cholesterol decreased again significantly. Thus, this case, which showed dramatic reductions of serum and LDL cholesterol levels, may be considered a new variant of heterozygous familial hypercholesterolemia, and the reductions were probably brought about by the action of estrogens, which are known to increase LDL degradation through LDL receptors.