This study is designed as a follow up study to that performed in 2005.

In the Baseline study (2005) extensive clinical whole body metabolic phenotyping was combined with in depth molecular and cellular biology analyses aimed at investigating the adipose tissue morphology as well as metabolic and inflammatory phenotypes in the adult GHD patients. Results published in (Ukropec et al., 2008)

In this study identical endpoints will be investigated with the same methodology and within the same population; in order to seek relevant answers to questions on how the 6-yrs of rhGH therapy affects the

• whole body insulin sensitivity
• energy expenditure
• body fat distribution
• hepatic and skeletal muscle lipid content;

as well as how it influences the adipose tissue

• endocrine,
• metabolic &
• inflammatory phenotypes.

The strength of the planned study lies in the extensive whole body and adipose tissue phenotyping before and after the 6-year rhGH replacement therapy, that allows to determine the long-term effects of rhGH replacement therapy in GHD adults.

Envisaged weakness is the limited size of the population; GHD adults (n=20); controls [age BMI and gender matched] (n=20). This, however, reflects [is limited by] the complexity of the study protocol as well as the stringency of the inclusion criteria.

The clinical data obtained by methods of - integrated physiology would provide an excellent interpretation background for molecular-genetic studies at the tissue (adipose tissue) and cellular (adipocytes) level. Integration of the two could bring a new quality in the investigators understanding of metabolic derangements present in GHD, and will allow extending the investigators knowledge on the mechanisms of the long-term rhGH-therapy-induced improvement on body composition, metabolic health and the cardiovascular risk.

Inclusion Criteria:

We will follow inclusion-exclusion criteria which are very much like those used in the pilot study performed in 2005.

• Briefly, duration of the GHD prior to entering the study should last for at least 3 years prior rhGH treatment starts. Age of individuals eligible to enter should be 20-50 years old. All patients and healthy control volunteers will provide the witnessed written informed consent before entry into the study.
• It has to be noted that differences in the etiology of GHD might influence several of the outcomes we plan to measure. Presence or absence of possible bias should therefore be excluded for each specific outcome prior further statistical data analysis. Individuals with different degree of pituitary deficiency will therefore be eligible to enter the study.
• Complex information on the adequacy of the hormone replacement therapy will be based on the serum levels of growth hormone, insulin-like growth factor 1, free thyroid hormone, testosterone/estradiol, urinary free cortisol FT4, and morning cortisol. Examination and laboratory testing relevant to this study will be performed within 6 months of entering the study. The 24-hour urinary free cortisol will only be determined in individuals hospitalized in a period of two month prior to the study entry.

Exclusion Criteria:

• None of the patients should receive lipid lowering treatment. Patients with malignant disease, diabetes mellitus, existing vascular disease and uncontrolled hypertension are not eligible to enter this study.

Twenty growth hormone deficient adults, receiving supplementation with rhGH for 5 years (extensively examined in 2005-2006, prior to the start of rhGH therapy) and 20 age-, gender- and BMI- matched controls will enter the study. Both, GHD patients and controls will undergo an extensive clinical protocol, identical to that performed in 2005 (Ukropec et al., 2008a).

The possibility of drop-out of patients needs to be taken into consideration. Possible lowering of the numbers of participants due to drop-out of individuals tested in the Baseline Study will be resolved by either (i) using biological material obtained in the Baseline Study which was originally not subjected to an extensive molecular genetic testing due to the limited capacity and high cost of these analyses and/or by (ii) recruiting necessary amount of new patients with history of 5 years rhGH therapy (initial examination is missing).