NEUROPHYSINS AS MARKERS OF VASOPRESSIN AND OXYTOCIN RELEASE - A STUDY IN CARCINOMA OF THE LUNG

Vasopressin-neurophysin (hN(p)I), oxytocin-neurophysin (hN(p)II) and blood osmolality were assayed before any treatment in basal conditions in 35 patients suffering from lung carcinoma (20 oat cell, 6 undifferentiated and 9 well-differentiated epidermoid cell carcinomas). Plasma vasopressin (antidiuretic hormone, ADH) was also assayed in 7 of the 20 patients suffering from oat cell carcinoma. We found a close correlation (r = 0.98) between plasma ADH and hN(p)I levels in the 7 patients. Further, hN(p)I was elevated in 13 out of 20 oat cell carcinoma patients and in none of the epidermoid-cell carcinoma group; however, searching for an abnormality of ADH secretion as reflected by a detectable plasma hN(p)I level together with subnormal plasma osmolality revealed 2 additional positive results in the oat cell carcinoma group, and 2 out of the 6 in the undifferentiated-cell carcinoma group. hN(p)II was increased together with an increase in hN(p)I in 6 oat cell carcinoma patients; it was specifically increased without hN(p)I increment in 2 additional oat cell carcinoma patients and in 2 patients of the undifferentiated-cell carcinoma group (different from the 2 positive for the hN(p)I-osmolality ratio). hN(p)I and hN(p)II were normal in the majority of undifferentiated and all of the differentiated epidermoid-cell carcinoma group. Hence, our results show that simultaneous measurements of hN(p)I, hN(p)II, and blood osmolality could detect abnormalities in 17 out of 20 oat cell carcinoma patients, in 4 of the 9 undifferentiated-cell carcinoma patients, but in none of the differentiated epidermoid-cell carcinoma patients, suggesting that the neurophysin assay can be used for the early detection of oat cell- and possibly other neuroendocrine-derived carcinomas.