A 46-year-old woman presented for anterior cervical discectomy and fusion of C5/C6 and C6/C7 vertebrae to treat a cervical myelopathy. She had a history of anxiety disorders, epilepsy, and mild intellectual impairment. She denied any recent sexual activity, but was 2 weeks late for her menstrual cycle. A serum point-of-care human chorionic gonadotropin (hCG) test was interpreted as positive but a urine point-of-care hCG test was interpreted as negative and a quantitative serum hCG was <2 IU/L (reference interval 0–5 IU/L).



  1. ​What are potential causes of the discrepant hCG test results?
  2. What tests can be done to investigate the discrepancy?​ ​
  3. ​Why did the patient have a low ionized calcium concentration despite a typical total serum calcium concentration and a low albumin concentration?​

What Is Your Guess? Read the article by Dina N. Greene, et al., here​ ​for the answers.