This clinical trial is focused on studying the effects of a medication called hydrocortisone in patients who have been diagnosed with Giant Cell Arteritis (GCA) or Polymyalgia Rheumatica (PMR). These are conditions that cause inflammation in the body, leading to symptoms like pain and stiffness. The study is particularly interested in patients who have stopped taking a type of medication called glucocorticoids, which are often used to treat these conditions. After stopping glucocorticoids, some patients may experience symptoms of adrenal insufficiency, a condition where the body does not produce enough of certain hormones.

The purpose of this study is to compare the effects of hydrocortisone with a placebo in managing these symptoms. Hydrocortisone is a medication that can help replace the hormones that the adrenal glands are not producing enough of. The study will last for 16 weeks, during which participants will receive either hydrocortisone or a placebo. The study is designed to be double-blinded, meaning neither the participants nor the researchers will know who is receiving the actual medication or the placebo, to ensure unbiased results.

Throughout the study, participants will be monitored for symptoms of adrenal insufficiency, as well as other health indicators such as fatigue, blood pressure, and muscle strength. The goal is to provide evidence-based guidance for managing adrenal insufficiency in patients who have stopped glucocorticoid treatment, addressing an important need for many patients with GCA or PMR. This study aims to improve the quality of life for these patients by finding effective ways to manage their symptoms after glucocorticoid treatment has ended.