Case 42

1. Presented by Robert Kruse, MD, PhD and prepared by Lori Sokoll, PhD

Clinical Vignette

An elderly female presents with an unexpected hCG positive result at hospital admission. The patient has a past medical history of end-stage renal disease (ESRD) on dialysis, hypertension, secondary hyperparathyroidism, hypercalcemia, who now presents with left hip pain. Imaging reveals a femoral neck fracture. Of note, she also has a family history of osteoporosis and a smoking history.

At the time of her admission, her serum hCG (human chorionic gonadotropin) level was unexpectedly positive on a routine screen for female patients. Urine hCG testing was not performed since the patient is anuric secondary to ESRD. Creatinine was 4.5 mg/dL on the date of admission. The clinician initially paged the pathology resident in the chemistry lab asking if this hCG result could be a false positive. Upon quantification, the patient's serum hCG concentration was determined to be 177.4 mIU/mL.

Which of the following is the most likely source of this patient's positive hCG test?