A low molecular weight substance obtained from serum which has luteinizing hormone like activity ("mini LH")

A low molecular weight substance of 1000-2000 daltons has been isolated in dialysates of normal human serum which, on testing in a radio-immunoassay, a radioligand receptorassay and an in-vitro bioassay exhibited LH activity comparable to the range of LH activity found in normal serum. The substance was heat labile. Its reactivity in a RIA suggests peptide nature. No "mini LH" activity could be derived from LH-free serum samples of hypophysectomized patients.