['Growth hormone (GH) circulating levels are highly dependent not only on GH secretion rate from the pituitary, but also on the hormone distribution in the compartments of the body and elimination phenomena. In adult GH-deficient patients these factors become critical nowadays, especially when recombinant human GH (rhGH) is available for replacement therapy. In the present study, we assess the influence of both distribution and elimination phenomena on GH pharmacokinetics in adult GH-deficient patients.', 'We used a four-step methodology following a compartmental approach after an intravenous bolus of recombinant GH in adult GH-deficient patients.', 'We found that GH kinetics are clearly explained by a bi-exponential, two-compartmental model in GH-deficient patients, similarly than in normal or diabetic subjects, as previously shown. We have also observed a marked delay in the whole GH elimination process in GH-deficient patients compared to normal adult subjects, as revealed by metabolic clearance ratio (MCR), elimination constant from central compartment (k(10)), and mean resident time in the body (MRT). Interestingly, such a delay appear to be caused by deep changes in the distribution phase (Mtt(1)- mean transit time-1; T(1/2alpha)- GH half-life at distribution phase), while the elimination phenomenon remains unaltered.'] Are growth hormone distribution kinetics markedly reduced in adults with growth hormone deficiency?