This is a wonderful and increasingly relevant question as it is not uncommon for someone to have a low alkaline phosphatase and be told it is not important since alkaline phosphatase is only important if it is elevated. Causes for this abnormality include protein deficiency, Wilson’s disease,...

Just a minor correction in that hypophosphatasia can result in osteomalacia/rickets and not osteoporosis. It is the profound skeletal hypomineralization that leads to osteomalacia with a disproportionate loss of bone mineral relative to the bone matrix. In osteoporosis, on the other hand, there is a...

Thanks, @Paul J. DeMarco for a well-thought-out, thorough answer. Note that these patients with hypophosphatasia exist and we need to catch them before they get so many fractures and severe secondary osteoarthritis. I have one patient who unfortunately already had many fractures and degenerative jo...

Very helpful in hypophosphatemia workup.

Metatarsal, so-called "stress fractures", or real ones as well as any prior fractures in a young person and persistent low ALP as mentioned above should raise concerns for HPP. The patients we see are adults for the most part as an adult rheumatologist myself. You have to enquire about childhood MSK...