Application of the human chorionic gonadotropin immunoassay in cerebrospinal fluid for the diagnostic work-up of neurohypophyseal germinomas
Víctor Luis González-Sánchez1, Oscar Moreno-Pérez1, Pedro Sánchez Pellicer2, Ruth Sánchez-Ortiga1, Monserrat Mauri Dot2, Elena Gastaldo Simeón3, Ignacio Aranda López4 & Antonio Miguel Picó Alfonso1
Context: The determination of human chorionic gonadotropin (hCG) in cerebrospinal fluid (CSF) is useful for the differential diagnosis of suprasellar lesions. However, the concentrations that prove diagnostic for neurohypophyseal germinoma have not been well defined. In addition, the immunoassays used for such determination are the same as those applied in serum, and few studies have been performed regarding the validation of such techniques in CSF.
Objective: The present study aims to apply the hCG+β immunoassay from Roche Diagnostics for determining hCG in CSF, in the diagnosis of neurohypophyseal germinomas in children and young adults.
Design and patients: Validation of the immunoassay has been established calculating the functional sensitivity and reference values for hCG in CSF in 35 subjects in the absence of pregnancy, trophoblastic disease or tumor pathology. For the clinical application study, three patients diagnosed with neurohypophyseal germinoma have been reviewed.
Results: The functional sensitivity obtained was 0.4 mIU/ml. The reference values for hCG in CSF ranged from undetectable values to 0.7 mIU/ml. The hCG concentrations in CSF in the three studied patients with confirmed diagnosis of germinoma by pathological sample or complete response to treatment, were 21.1, 32.6 and 23 mIU/ml, respectively.
Conclusions: The hCG+β immunoassay from Roche Diagnostics is useful in the diagnosis of neurohypophyseal germinomas. Acording to our results, CSF-hCG levels that exceed the established reference interval (undetectable values to 0.7 mIU/ml), in children and young adults with suprasellar lesions and hypophyseal stalk thickening, is highly suspicious of germinoma.