CSF and serum hCG in patients without gestational and neoplastic hCG-secretion.

BACKGROUND: The measurement of human chorionic gonadotropin (hCG) in cerebrospinal fluid (CSF) is important for the diagnosis of intracranial or intraspinal trophoblastic tumours. The current study was performed to establish reference values for hCG in CSF and to explore the relationship of CSF hCG and serum hCG in patients who are not pregnant or do not have trophoblastic tumours. MATERIAL AND METHODS: CSF samples were obtained from 369 inpatients admitted because of various neurological diseases, excluding pregnancy, trophoblastic tumours and other malignant tumours. In 271 of the 369 patients, paired samples of CSF and serum were obtained. Both CSF hCG and serum hCG were measured. The 97.5th percentile and maximum value of CSF hCG were obtained. The CSF hCG and serum hCG concentrations in each of the 271 paired samples were compared. RESULTS: The 97.5th percentile and maximum value of CSF hCG concentration for overall participants were 1.00 and 5.00 IU/L, respectively. The CSF hCG concentration was found to be higher than the simultaneous serum hCG concentration in 81.9% (222/271) of the participants. CONCLUSIONS: The reference value determined in this study of CSF hCG in men is significantly lower than that usually used in clinical practice. A CSF hCG concentration higher than the simultaneous serum hCG concentration but lower than the upper reference limit does not necessarily suggest abnormal intrathecal hCG-secretion.