We will examine a cohort of growth hormone deficient adults starting growth hormone (GH) replacement. The purpose of this study is to determine whether GH replacement reduces the fat content of the liver.

To compare the results we will include growth hormone deficient patients who do not start GH replacement as controls.

Adults with untreated growth hormone deficiency (GHD), a condition mostly due to pituitary disease, often show metabolic features similar to those described in the 'metabolic syndrome'. Growth hormone (GH) replacement has been shown to reverse many of these unfavorable changes, with a particular evident reduction of visceral fat. In recent years, a strong correlation between fat accumulation in the liver and features of the metabolic syndrome (particularly visceral fat) has been identified, and 'fatty liver' is now being referred as the hepatic feature of the 'metabolic syndrome'. The effect of GH replacement on liver fat, however, has never been systematically studied.

We will assess 15 patients with GHD before and 6 months after starting GH replacement. We will also assess 15 control patients with GHD but who don't go on GH replacement for various reasons.

Liver fat will be assessed using MR spectroscopy. Changes in liver fat will be correlated to changes in insulin sensitivity and changes in various inflammatory markers.

Inclusion Criteria:

• 20-70 years of age
• Growth hormone deficiency, with (cohort 1) or without (cohort 2) planned growth hormone (GH) replacement
• clinically stable

Exclusion Criteria:

• known hepatic disease
• Acromegaly
• Diabetes mellitus
• growth hormone replacement within the last 12 months
• cushing's disease, if not cured for at least 12 months
• any contraindication to MR studies as set out in the MR safety questionnaire

Patients will be recruited from the endocrine clinics of Imperial College Healthcare NHS Trust.