Heterogeneity of adult hypophosphatasia. Report of severe and mild cases
R. S. Weinstein and M. P. Whyte
Two cases of women with adult hypophosphatasia illustrate the clinical
spectrum and potential difficulties in the diagnosis of this condition.
Both patients had subnormal serum alkaline phosphatase activity, absence of
leukocyte alkaline phosphatase, increased amounts of urinary
phosphoethanolamine, and normal levels of immunoreactive calcitonin and
parathyroid hormone. In undecalcified bone biopsy specimens, the number of
osteoblasts and the tetracycline-labeled calcification front were similar
in the two patients, although the percentage of unmineralized bone matrix
and the extent of osteoid-covered bone surface were different. Twenty years
of bone pain, severe skeletal deformities, and a generalized increase of
osteoid in one patient contrasted with an 18-month history of bone pain and
patchy osteoid in the other. These cases suggest that adult
hypophosphatasia is a heterogeneous disorder and may be more common than
previously realized.
