Adult hypophosphatasia and a low level of red blood cell thiamine pyrophosphate.

OBJECTIVE:To report the first adult case of hypophosphatasia and absence of intestinal alkaline phosphatase (ALP) isoenzymes associated with a low level of red blood cell thiamine pyrophosphate. METHODS:We describe the clinical manifestation and laboratory findings in our patient and discuss underlying factors that potentially contribute to her condition. RESULTS:A 33-year-old Vietnamese-American female was referred for a long history of low levels of serum ALP and absence of intestinal ALP isoenzyme. She had a normal level of urinary phosphoethanolamine and a high level of plasma pyridoxal-5p-phosphate. She was found to have a low level of red blood cell thiamine pyrophosphate. CONCLUSION:Our adult case of hypophosphatasia presented with an absence of intestinal ALP isoenzyme that might result in decreasing the absorption of thiamine in the intestinal tract. Therefore, the thiamine level should be considered in hypophosphatasia with absence of intestinal ALP isoenzyme.