What is this common underdiagnosed disease?

Diet - lack of iron in the diet - (stated to be a more uncommon reason for deficiency)

Food/drinks that inhibit iron absorption are: phosphates (sodas), polyphenols (red wine, purple grape juice, coffee, tea, spices, some fruits, some vegetables), wheat bran, phytates (phytic acids found in legumes, grains and rice can decrease absorption by 50%), tannins (teas, coffees), manganese, cobalt, copper, cadmium (in cigarette smoke), calcium, legume protein (soybeans, lentils, black beans, mung beans, and split peas), lignin (fibrous tissued vegetables) and soy protein.

Vitamins and minerals needed for iron metabolism - Vitamin B12 - iron needs vitamin B12 to be effectively metabolised. Vitamin A helps to mobilize iron from its storage sites, so a deficiency of vitamin A limits the body’s ability to use stored iron. Copper is needed for normal iron metabolism.

Drugs - alcohol, acid blockers, antibiotics, anti-inflammatory drugs or anti-coagulant medications.

Malabsorption diseases like coeliac disease and ulcerative colitis

Chronic diseases such as rheumatoid arthritis, kidney disease, diabetes, cancer, inflammatory bowel disease, a family history of inherited anaemia, chronic infections such as tuberculosis or HIV

Hormone disorders – such as hypothyroidism

Blood loss – due to trauma, surgery, cancer, peptic ulcer, heavy menstruation, bowel cancer or frequent blood donations

Periods of rapid growth or high energy requirements – such as puberty or pregnancy

I think it's hypothyroidism. I have this disease and am now on meds for it, but after dealing with tons of medical issues for years it took my Dr. 10 years to diagnose me, now all is well. But I'm not a dr and not even in the medical field, but this seems to effect soooooo many people!

Cirrhosis of the liver

and..?