There are a ton of reasons why hair can thin and fall out. Thyroid and anemia issues can be two HUGE culprits. As can stress, a diet without enough protein, etc. Typically with alopecia you will see circular spots of thinning or missing hair. Stress, anemia, and thyroid issues tend to make the hair thin out all over. When did you have your last child? I have seen hair fall out in my clients for up to two years after giving birth (myself icluded). Actually up to 150 to 200 hairs a day is normal (about a small palm full) is normal. It's when you have more than this, or you notice patches of missing hair, or noticeably thinning hair (scalp is beginning to show) that is of concern. Keep in mind that when we shed our hair normally it is at a point of being 5 to 7 years old, and that we do not put in a full head of hair all at once when we are born(it takes 3-5 years) to put ina full head of hair from birth), and that we have thousands upon thousands of hairs on our head to begin with :) Also, do you feel well in general, or are there other things going on? I had a client who for years her hair was so thin around the temples that all we could do was cut a heavy bang to "disguise" it. Awhile back I noticed her hair seemed thicker at the scalp, she thought I was nuts, then she began to notice it too...well it came out that she had been to her doctor about six months prior for some heallth issues, and had diagnosed her as being anemic...put her on iron pills, and hair began to grow back. Now don't get me wrong, she never had, and never will have a glorious head of hair, but it was no longer so thin that we left without options. I had been very ill, without really knowing what was wrong with me until this summer, and my hair was dry, and brittle, and just breaking off at the root. Now I am feeling better, and my hair is bouncing back. I'd say that if it has been under a year since you had your last child, and you are feeling relatively well maybe ask your OBGYN, if it has been over year, feeling under the weather, etc. I'd see your primary care physician, and have some blood work done. More than likely it is as simple as needing a nutritional supplement, if it isn't you find out what is going on, and move on from there.