Leydig Cell Function in Men with Gonadotrophin-Producing Testicular Tumors1

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Abstract
Seven men with gonadotrophin-producing testicular tumors were found to have normal plasma testosterone concentrations in spite of 10 to 50,000 times normal gonadotrophin production. In all 7 patients plasma testosterone was suppressed by 40 mg fluoxymesterone daily for 3 days, although plasma HCG concentrations remained unchanged. These data suggest that Leydig cell function was maintained by pituitary LH and that the patients were unresponsive to their Own tumor gonadotrophin. Tumor gonadotrophin from one patient was shown to stimulate testosterone production in another man, and was thus considered biologically active. No evidence for circulating gonadotrophin antibodies was found. When the patients were challenged with HCG and tumor gonadotrophin there was no increase in plasma testosterone, although 2 patients exhibited minimal increase in testosterone when given massive doses of tumor gonadotrophin. It is unclear how men with gonadotrophinproducing tumors have normal plasma testosterone levels which are suppressed by exogenous androgen, and yet are unresponsive to administered gonadotrophins. Estrogen production rates and excretion were 5- to 10-fold elevated in 2 patients studied, but could be entirely accounted for by tumor metabolism of circulating C19O2 steroids, notably dehydroepiandrosterone sulfate.

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