No abstract

THE original observations that the placenta produces a gonadotrophic hormone which is excreted in the urine (Hirose, 1920;Aschheim and Zondek, 1927) were soon followed by identification of a similar hormone in the urine and blood of patients with hydatidiform mole and choriocarcinoma (Zondek, 1929(Zondek, , 1942 Hamburger, 1944). These conditions were sometimes found to be associated with higher excretion rates of human chorionic gonadotrophin (HCG) than were usually found in normal pregnancy but it is now recognised that in choriocarcinoma high values simply reflect extensive disease and in many instances the excretion rates of HCG are comparable to, or lower than those of normal pregnancy.The problem of distinguishing hydatidiform mole and choriocarcinoma from normal pregnancy led Ehrhardt (1931) to examine the spinal fluid for gonadotrophic activity by the Aschheim-Zondek test. He obtained positive responses with CSF from 2 patients with hydatidiform mole but no response with the CSF of normal pregnant women. Zondek (1937Zondek ( , 1942, Mathieu (1939) and Vesell and Goldman (1941) confirmed these findings on small groups of patients with inole, choriocarcinoma and normal pregnancy. On their evidence a positive pregnancy test on spinal fluid acquired a reputation as a means for distinguishing choriocarcinoma from normal pregnancy. McCormick (1954) studied patients with hydatidiform mole and also infused HCG into a nephrectomised dog. He concluded that the ratio of blood and spinal fluid concentrations was about 187: 1 and that HCG did not appear in the CSF until a high threshold value (excretion of 250,000 i.u. HCG/day in the urine) was exceeded. Tashima et al., (1965) also concluded that HCG did not appear in the CSF until a high threshold value was exceeded unless the patient had brain metastases from choriocarcinoma.Radioimmunoassay provides a more sensitive method for the quantitation of gonadotrophic hormones than the bioassay methods previously used. By radioimmunoassay it has been found that the concentration of HCG in the CSF of patients with trophoblastic tumours is directly proportional to the concentration in the plasma (Bagshawe, Orr, and Rushworth, 1968). In the present paper we compare the concentration of HCG in the CSF of patients with choriocarcinoma which has metastasised to the central nervous system (CNS) with the values found in patients who had no evidence of such metastases. MATERIALS AND METHODSDetails of the method, sensitivity and specificity of the radioimmunoassay have been described by Bagshawe (1965, 1967) and by Bagshawe, Wilde and Orr (1966). The method estimates both HCG and luteinising hormone (LH) and requires approximately 1 ml. of the sample fluid. Total CSF protein was estimated by a turbidimetric method using sulphosalicylic acid.