Free T4, free T3 and free reverse T3 in dialysates of serum. The influence of electrolytes and pH with special reference to the physiological range.
The influence of electrolyte composition and pH of buffer on free T4, free rT3, and free T3 concentrations in serum dialysates has been evaluated, using an equilibrium dialysis method with subsequent direct radioimmunoassay estimations of the dialysate. Cl-, HCO3- and H+ were found to be the important ions which at concentrations similar to those occurring in vivo decreased the protein binding of all three hormones in serum, T3 being much less sensitive to these changes than T4 and rT3. The possible influence of pathological concentrations of electrolytes in serum on estimated free thyroid hormone concentrations is discussed. Because the effect of in vivo changes in serum Cl-, HCO3- and H+ on free thyroid hormone concentrations to a certain extent tend to counteract each other, it is concluded that electrolyte and pH disturbances only to a minor extent can affect measurements on free T4, free rT3 and free T3 concentrations in serum obtained by an equilibrium dialysis method.
D001769:Blood; D002021:Buffers; D004573:Electrolytes / Q000097:blood / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011863:Radioimmunoassay; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*; D014285:Triiodothyronine, Reverse / Q000097:blood*
D002021:Buffers; D004573:Electrolytes; D014284:Triiodothyronine; D014285:Triiodothyronine, Reverse; D013974:Thyroxine