I have a myriad of reasons for my fatigue, shortness of breath, lack of motivation, headaches, lack of concentration, feeling very cold in my feet/hands, etc. (I have hypothyroidism, PCOS, fibromyalgia, asthma, migraines, & adult ADD -- I'm actually taking meds for each of these conditions too). However, I've been feeling a sharp intensity in the above symptoms, which is why I went to my GP. Long story short, I have yet another reason contributing to the above symptoms: iron deficiency. My TSH (thyroid levels) were fine, but my ferritin levels are at 21 ug/L. How low is this? Would this explain the above symptoms?
Of course, as soon as I muster enough energy, I'll walk to the nearest pharmacy and get iron supplements. However, I'm wondering... How long does it take for iron supplements to impact my health at all? Will I notice improvements immediately? Or is it more of a gradual thing that takes weeks before noticing more energy and focused concentration, etc? (Don't worry, I'll be taking it long-term... I'm just wondering if I'll see improvements fairly quickly as I have my Oral Exams -Grad School- in 6 days, and want my brain to be in tip-top shape).