TRANS-BLOOD-BRAIN-BARRIER ALBUMIN LEAKAGE AND COMPARISONS OF INTRATHECAL IGG SYNTHESIS CALCULATIONS IN MULTIPLE-SCLEROSIS PATIENTS

We compared four equations for estimating intrathecal IgG synthesis (T ibbling and Link IgG index (T/L), Schuller and Sagar (S/S), Reiber and Felgenhauer (R/F), and Tourtellotte (T) equations) using data from ch ronic progressive MS patients. For normal albumin leakage (AL) (< 75 m g/day - intact BBB), T (r = 0.15) and R/F (r = 0. 10) showed comparabl e positive correlations with trans-BBB AL, T/L (r = - 0. 10) was negat ive and S/S was uncorrelated (r = 0.05). For abnormal AL (greater-than -or-equal-to 75 mg/day), the R/F (r = - 0.24), S/S (r = - 0.37) and th e T/L (r = - 0.22) equations overcorrected, whereas the T (r = 0.07) e quation values did not correlate with AL. The albumin index and trans- BBB albumin leakage rate formulae gave essentially identical estimates of BBB leakage (r = 0.99, P = 0.0001). We conclude that in chronic pr ogressive MS patients the R/F, T/L and S/S formulae overcompensate for large abnormal T-BBB albumin leakage rates. The T formula corrected b est for IgG transudate at high AL rate values in MS.