History and Physical Exam

History

48-year-old woman with a past history of mental illness presents with a new onset of bizarre psychotic behavior. She had been well for the past two years

Physical Exam

She was 5'5" tall and weighed 138 lb. Her heart rate was 80 and her blood pressure was 130/75. The physical exam was otherwise normal except that she was confused as to the current location, the date, and the year.

Initial Laboratory Tests

Routine hematology and chemistry tests were normal except: 
                       Patient         Reference
Calcium (S)          13.8 mg/dl       8.4 - 10.1
Phosphorus (S)        2.8 mg/dl        2.5 - 4.5
Chloride/Phos ratio    38 : 1            <29 : 1

Questions

  1. How would you interpret the patient's presentation?
  2. What would be the next step in your workup?