THYMULIN, ZINC AND INSULIN-LIKE GROWTH-FACTOR-I (IGF-I) ACTIVITY BEFORE AND DURING RECOMBINANT GROWTH-HORMONE (REC-GH) THERAPY IN CHILDREN AND ADULTS WITH GH DEFICIENCY

Plasma thymulin (active and total) levels, IGF-I and zinc concentratio ns were evaluated in 9 children and in 8 adults with GH deficiency (GH D) before and after 3-6 months of recombinant-GH treatment. Before the rapy, GH deficient children had lower plasma active thymulin levels (1 .0+/-0.3 log(-2)), not due to a peripheral defect in zinc saturation s ince plasma zinc levels were within the normal range, and total thymul in levels (1.3+/-0.3 log(-2)) than in the agematched control group. GH therapy significantly increased active thymulin (3rd month: 3.0+/-0.2 log(-2), 6th month: 4.0+/-0.2 log(-2)), total thymulin (3rd month: 3. 3+/-0.3 log(-2), 6th month: 4.3+/-0.2 log(-2)) and IGF-I levels (3rd m onth: 283.3+/-7.2 mu g/L, 6th month: 411.2+/-44.2 mu g/L, vs basal: 14 4.3+/-11.5 mu g/L); at the 6th month of therapy, thymulin levels (acti ve and total) were comparable to those found in controls. A positive c orrelation existed between zinc and plasma IGF-I levels (r=0.66, p<0.0 5). In adults with GHD, plasma active (1.9+/-0.3 log(-2)) and total th ymulin levels (3.9+/-0.1 log(-2)), significantly lower (p<0.01 and 0.0 5, respectively) than in controls before treatment, increased after GH therapy (active thymulin, 3rd month: 3.0+/-0.2 log(-2), 6th month: 4. 4+/-0.3 log(-2); total thymulin, 3rd month: 3.9+/-0.3 log(-2), 6th mon th: 4.71+/-0.2 log(-2)), being at 6th month of therapy no more differe nt from the values recorded in the age-matched control group. In concl usion, children and adults with GHD have a marked impairment of the th ymic endocrine activity, which can be restored by six months of GH tre atment. The effects of GH on thymic functions may be mediated by IGF-I , through the modulation of zinc turnover, suggesting the possible exi stence of an interplay among GH, zinc, IGF-I and thymulin both in chil dren and adults with GHD. (C) 1996, Editrice Kurtis