Unexplained weight gain and very low serum cortisol

@aa12, I'm sorry you feel so anxious about your weight gain and low cortisol level. It's important for your Endocrinologist to first determine what is causing your cortisol level to be low and which type of Adrenal insufficiency you have as that answer determines the treatment. With a very low cortisol level, you will need to be placed on a steroid and the dose will be regulated by the symptoms you report during your initial trial period. Replacement of the missing cortisol will help keep your body systems stable and finding the right dose for you is the key. Plus there are several types of replacement steroids, and the 3 most common are: Hydrocortisone which is closest to the body's natural production, but is a short acting medication meaning you have to take smaller doses of it divided up during the day to keep it in your system, Prednisone which has a longer lasting effect but still needs to be taken in divided doses and Dexamethasone which is the most potent steroid and is taken as a single dose and lasts roughly 24 hours depending on your metabolism. When our cortisol levels are severely deficient, it impacts weight gain because it affects our metabolism process and often reduces our activity level because now we are lacking in energy as well. Once you and your Endocrinologist discover which of your other hormones have been affected by the damage to either your adrenal glands themselves called Primary Adrenal Insufficiency (PAI) or Addison's disease or to the Pituitary gland called Secondary adrenal insufficiency (SAI) or to your Hypothalamus called Tertiary Adrenal Insufficiency (TAI), those hormones can be replaced with medication therapy and eventually, if you have no other severely incapacitating comorbidities, your body systems and functions will become better regulated. I have Secondary adrenal insufficiency (SAI) caused by being on an extended high dose steroid trial over 3 years ago to determine if my pancreatitis was an autoimmune type. Last year, in 2023, I realized that while always feeling a little chilly, I was unable to regulate my body temperature and could stand in a hot shower and be shivering and was sleeping under 6 blankets year round in Texas! A genetic test from Amazon confirmed that I had a low basal metabolic rate and I went in search of answers. After 4 doctors, I found my Endocrinologist and he started, as insurance dictates, with the Thyroid hormones which, like yours, were all normal including the thyroid scan. When we tested my cortisol and did the ACTH Stimulation Test, we discovered the cause. I also had a brain scan to rule out TAI. Long story short, your hormones are deficient and need replacement and this will help with your weight gain issue. I'm happy to help if you have additional questions. Sending you a big hug today!