METHOD-DEPENDENT INCREASE IN LIPOPROTEIN(A) IN INSULIN-DEPENDENT DIABETES-MELLITUS DURING PREGNANCY

The current prevalent view is that plasma lipoprotein(a) [Lp(a)] conce ntrations are under strong genetic control. Most dietary and drug inte rventions seem to have little or no effect on plasma Lp(a) levels. How ever, evidence for a possible regulatory role of hormones is accumulat ing, for instance, fluctuations of Lp(a) levels during pregnancy have been reported. Also, in insulin-dependent diabetes mellitus (IDDM) pat ients, elevated Lp(a) levels have been reported. In the present longit udinal study, plasma lipid concentrations, including Lp(a), were deter mined in IDDM women before pregnancy, during pregnancy, and 3 months p ostpartum. In our study population, Lp(a) concentration was not signif icantly correlated with either hemoglobin A(1c) (HbA(1c)) levels or ap olipoprotein(a) [apo(a)] phenotype. Changes in other lipid parameters observed during pregnancy in our IDDM population were similar to those reported during normal pregnancy. Lp(a) concentrations were quantifie d using two different immunochemical methods that possess different se nsitivities and specificities: an immunoradiometric assay (IRMA) using two different anti-apo(a) antibodies, and an enzyme-linked immunosorb ent assay (ELISA) using an anti-apo(a) and an anti-apo B antibody. Med ian prepregnancy Lp(a) concentrations were 118 mg/L (range, 15 to 672) as determined with the IRMA and 107 mg/L (range, 21 to 451) as determ ined with the ELISA. Women with IDDM showed, in general, no significan t change in Lp(a) concentration during pregnancy when it was assayed w ith the IRMA, although a tendency to increased values was observed. Wh en Lp(a) concentrations were determined with the ELISA, a strong and s ignificant increase in Lp(a) from weeks 17 to 24 of pregnancy onward w as found. The latter results confirm the prevalent view that during pr egnancy Lp(a) levels are increased. However, the present results and t hose of others on Lp(a) in normal pregnancy strongly emphasize the imp ortance of method selection when determining Lp(a) concentrations. Cop yright (C) 1995 by W.B. Saunders Company