Hypothyroidism - Can you have it even if it doesn't show up in the initial blood test?

Know someone who has many of the symptoms of hypothyroidism, ie: dry, brittle cuticles/nails, joint pain, fatigue, sketchy memory here and there, trouble maintaining weight (though exercizes daily and has fairly healthy diet). Also has had onset of many food/and a few antibiotic allergies in the past couple of years, and sudden predisposition to either psoriosis or eczema in the winter (dry/CA) months. All seems to lead to a compromised immune system, but preliminary blood works does not indicate hypothyroid issues......Quite perplexed.

Yes, you can be hypothyroid and not have the blood test show it. Unfortunately, a blood test is the only form of diagnosis for hypothyroidism and it is not reliable. Sometimes it will take up to 10 years, after showing symptoms, before the blood work will show it and, for some, the blood work will never show it. I also have all the symptoms and it runs in my family...my doctor admits I have them...but without the blood test to back them up, he will not treat it. I told him I know the blood test may never show it and he admitted I was correct...but without documentation, does not feel right treating me for it.

I'd like to suggest one other thing. Find out if your friend's doctor ordered a cortisol level (another blood test). The symptoms of hypothyroidism and an elevated cortisol level can be quite similar in the beginning. When the symptoms are present, and the thyroid tests are normal, it is often worthwhile to check the cortisol level.