A 40-year-old female visited our hospital because of malaise. She had no history of early loss of primary teeth nor family history of skeletal dysplasia. Laboratory examination showed low serum alkaline phosphatase levels of 18 U/L. In addition, hypozincemia was also observed, but alkaline phosphatase level did not increase after zinc replacement. Mediators, including calcium and phosphorus metabolism, were within normal range. X-ray examination showed no evidence of osteomalacia, but mineral bone density was slightly decreased compared with the young adult mean. Urine phosphoethanolamine level was increased, and we then suspected hypophosphatasia. Genetic tests detected ALPL gene heterozygous missense mutation (c.529G>A p.Ala177Thr and c.670A>G p.Lys224Glu) and adult-onset hypophosphatasia was finally diagnosed. It is important to evaluate alkaline phosphatase levels in the screening of patients with non-specific symptoms.

Very-late-onset schizophrenia-like psychosis (VLOSLP) is a condition in which psychotic symptoms emerge after the age of 60 years. Given its heterogeneous nature, VLOSLP remains a diagnostic and therapeutic dilemma. Here, we report a case of a 68-year-old patient with psychosis refractory to antipsychotics who was successfully treated with mirtazapine monotherapy. This case suggests that mirtazapine monotherapy may be effective for the treatment of patients with antipsychotic-refractory VLOSLP.