Endocrine Abstracts

Adult growth hormone deficiency (GHD), a condition characterized by increased oxidative stress (OS), is related to augmented cardiovascular, metabolic and oncological risk. Thymidine-glycol (ThyG) (5, 6-dihydro-5, 6-dihydroxy-2’-deoxythymidine) is a marker of DNA oxidation produced when thymidine is damaged by hydroxyl radicals. It is considered a specific marker since it is not incorporated in RNA; while 8-OH-deoxyguanosine, a well-known marker of oxidative damage, is rapidly excised from DNA and excreted in the urine, ThyG remains in tissues, thus representing an appropriate marker for oxidative tissue DNA damage. A case–control observational study has been performed to evaluate DNA oxidative damage analysing the production of ThyG in lymphocytes and its correlation with plasma antioxidant levels, evaluated as Total Antioxidant Capacity (TAC). GHD was diagnosed using GHRH 50 µg iv + arginine 0.5 g/kg test, with peak GH response <9 µg/l when BMI was <30 kg/m² or <4 µg/l when BMI was >30 kg/m². 16 patients, 9 males and 7 females, were classified as total GHD group; 11 patients, 5 males and 6 females, with GH peak between 9 and 16 ng/ml were considered as partial GHD group. Finally, 12 subjects, 7 males and 5 females, with GH peak > 16 ng/ml were included as control group. Age in total GHD group ranged from 37 to 70 years, in partial GHD group from 24 to 70 years and from 23 to 70 years in control group. Median ± interquartile BMI were 27.14 ± 2.85 kg/m², 26.23 ± 8.36 kg/m² and 22.51 ± 1.26 kg/m² in total GHD, partial GHD and control respectively. ThyG, TAC and IGF-1 have been determined respectively in lymphocytes, plasma and serum samples. ThyG levels were examined and interpreted with an optical microscope by three readers independently, who gave, respectively, a score from 1 to 5; the mean of the three evaluations was considered for each sample. When considering ThyG, we found a significant difference between total vs partial GHD and controls (mean ± s.e.m. 2.25 ± 0.4; 3.21 ± 0.47; 3.64 ± 0.49, respectively). Unexpectedly ThyG was lower in total GHD. The last datum was accompanied with a significant increase in plasmatic TAC, which was higher in total GHD vs the other two groups (70.00 ± 3.14; 47.14 ±€5.65, 43.75 ± 1.83 s, respectively). Our results showed that in adult GHD, the production of antioxidant species, in response to increased oxidative stress, could exert a protective effect on ThyG formation, and consequently on DNA intracellular damages.