Concentrations of CSF proteins as a measure of blood brain barrier function and synthesis of IgG within the CNS in 'normal' subjects from the age of 6 months to 30 years.

Concentrations of proteins in cerebrospinal fluid (CSF) and serum have been studied in 105 'normal' subjects divided into age groups 0.5-5, 6-15, 16-20, and 21-30 years in order to obtain reference values for information concerning blood brain barrier damage and synthesis of immunoglobulins within the central nervous system (CNS). CSF/serum albumin ratio is superior to CSF total protein as a test of the blood brain barrier function. The IgG synthesis rate per 24 hours and IgG index [CSF/serum IgG ratio]: [CSF/serum albumin ratio] reflect the presence of IgG synthesis within the CNS. The variables reflecting the blood brain barrier function increased with age, the upper values of the CSF/serum albumin ratio being 4.0, 4.9, 6.7 and 6.5 for the mentioned age groups respectively. The upper values for the CSF IgG index remained rather constant in relation to age at 0.62, 0.68, 0.64, and 0.63 respectively. An index value of less than 0.70 and an IgG synthesis of less than 10 mg/24 hours seem to be appropriate upper values as references. Only about 1--2 ml of CSF and 0.5 ml serum are required for the analyses including cell counting and determinations of IgA and IgM index values as well as of glucose and lactate.