D-THYROXINE REDUCES LIPOPROTEIN(A) SERUM CONCENTRATION IN DIALYSIS PATIENTS

Uremia raises lipoprotein(a) (Lp(a)) serum concentration and the risk of arteriosclerosis in dialysis patients. The treatment of high Lp(a) levels is not satisfactory today. The decrease of Lp(a) in hypothyroid patients on L-T4 therapy raised the question of whether dextro-thyrox ine (D-thyroxine) reduces not only serum cholesterol, but also Lp(a) s erum concentration. In a single-blind placebo-controlled study, the in fluence of D-thyroxine therapy on Lp(a) serum concentration was evalua ted in 30 hemodialysis patients with elevated Lp(a) serum levels. Lp(a ) was quantified in parallel by two methods, i.e., rocket immunoelectr ophoresis and nephelometry, and apo(a) isoforms were determined by a s ensitive immunoblotting technique. Regardless of the apo(a) isoforms, 6 mg/d D-thyroxine reduced elevated Lp(a) levels significantly by 27 /- 13% in 20 dialysis patients (P < 0.001) compared with 10 control su bjects (-9.9 +/- 8.4%). In parallel, D-thyroxine therapy significantly lowered total cholesterol (P < 0.001), LDL cholesterol (P < 0.001), a nd LDL cholesterol/HDL cholesterol ratio (P < 0.01); raised T4 and T3 serum levels; and suppressed thyroid-stimulating hormone secretion wit hout causing clinical symptoms of hyperthyroidism in any bf the patien ts. D-Thyroxine reduces elevated serum Lp(a) concentration in dialysis patients. The effect in nondialysis patients can be expected but rema ins to be proven.