Reduced capillary permeability and capillary density in the skin of GH-deficient adults: improvement after 12 months GH replacement

OBJECTIVE Several lines of evidence suggest that the GH-IGF-1 axis affects capillary permeability and angiogenesis. We evaluated skin capillary permeability and capillary density in GH-deficient adults, before and after GH replacement therapy. PATIENTS Seven normotensive, nondiabetic GH-deficient adults (two women) were matched with 14 control subjects. MEASUREMENTS Large-window videodensitometry with sodium fluorescein was performed in all subjects. Capillary permeability was expressed as the average relative light intensity over the first 7 min after the appearance of fluorescein in the skin capillaries; l(av)(7). Skin capillary density was determined by counting the visualized capillaries and was expressed as n/mm(2). The GH-deficient patients were restudied after 12 months of GH replacement therapy (2 U/day). RESULTS Both capillary permeability and capillary density were lower in untreated GH-deficient patients than in control subjects (median, interquartile range): I-av(7) in GH-deficient patients 47.1 (45.1-52-2)% vs. 57.5 (50.5-64.8)% in controls, P <0.05; capillary density in GH-deficient patients 18 (12-24)/mm(2) vs. 32 (26-36)/mm(2) in controls, P <0.05. GH treatment normalized plasma IGF-1 from 4.3 (1.0-13.4) to 22.2 (19.8-48.2) nmol/l (P <0.05). Furthermore, both capillary permeability [I-av(7) 53.1 (48.8-58-4)%, P <0.05] and capillary density [26 (17-34)/mm(2), P <0.05] increased to a level that was not different from that in control subjects. CONCLUSIONS The present study demonstrates that the growth hormone deficiency syndrome is associated with microvascular alterations, which are responsive to growth hormone replacement therapy.