SERUM INSULIN-LIKE-GROWTH-FACTOR-II IN 44 PATIENTS WITH NON-ISLET CELL TUMOR HYPOGLYCEMIA

Serum insulin-like growth factor II (IGF-II) was characterized by radi oimmunoassay and Western immunoblot in 44 patients with non-islet cell tumor hypoglycemia (NICTH). 31 of 44 patients with NICTH had big IGF- II in sera. When the presence of IGF-II in tumors from 20 patients was investigated, IGF-II in tumors was detected in 18 patients and these patients had big IGF-II in sera. In two patients whose tumors did not contain IGF-II, big IGF-II in sera was not detected. In six patients w ith IGF-II in tumors, hypoglycemia disappeared and the big IGF-II decr eased after successful removal of the tumors. These data indicate that the big IGF-II could be related to hypoglycemia, and that the increas ed serum big IGF-II suggests IGF-II-producing NICTH. Serum IGF-II leve ls in 31 patients with big IGF-II were greater than those in 13 patien ts without it (Mean +/- SEM: 723 +/- 54 vs. 326 +/- 31 ng/ml), but the elevated IGF-II levels were found in only 13 patients. Serum IGF-I le vels were low in all patients with NICTH. In the 13 patients without b ig IGF-II, serum IGF-II levels were lower than those in the patients w ith big IGF-II, and serum IGF-I levels were also low. Serum IGF-II/IGF -I ratios in the patients with big IGF-II were elevated and greater th an those in the patients without big IGF-II (35.0 +/- 2.2 vs. 11.5 +/- 2.4). The present data indicate that IGF-II-producing tumors are not rare in NICTH, and serum big IGF-II and IGF-II/IGF-I ratio are useful for screening patients with IGF-II-producing NICTH.