Fractionation Studies on Plasma of Normals and Patients with Laron Dwarfism and Hypopituitary Gigantism

The molecular size of immunoreactive human growth hormone (IR-HGH) in serum and the relationship of IR-HGH to sulfation factor (SF) require further investigation. Sera obtained from normal volunteers, patients with Laron-type dwarfism, and hypopituitary patients with gigantism were fractionated on large columns of Sephadex. The IR-HGH in normal serum was found in a molecular size range similar to extracted pituitary HGH (epHGH), as well as in a larger and a smaller molecular size. Laron dwarf plasma had a similar molecular size IR-HGH distribution when compared with normal serum. Sera from hypopituitary patients with gigantism showed an increased relative amount of small IR-HGH compared with normal serum. SF activity was recovered in normal serum but not in other sera fractions. SF activity appeared mainly in the molecular size range less than 17 000 and another peak was noted in the molecular size area greater than 55 000.This study further supports the existence of IR-HGH in a large and a small molecular size in normal serum. IR-HGH in Laron dwarf serum appears similar in molecular size to normal serum IR-HGH. The relative increase in small IR-HGH in hypopituitary patients with gigantism requires further investigation. SF activity appears in a molecular size different from epHGH in normal serum, the main peak being in a smaller molecular size area, with a lesser peak in a larger size area.