A 65-year-old woman is brought to the emergency department due to progressive lethargy and generalized weakness. She has also had loss of appetite, constipation, muscle weakness, and increased thirst and urination. The patient's medical history is unremarkable. She takes no prescription medications. The patient does not use tobacco, alcohol, or illicit drugs. On physical examination, she is stuporous and has dry mucous membranes. Laboratory testing shows serum calcium of 14.0 mg/dL and normal serum glucose and urinalysis. Imaging studies reveal an 8-cm right lung mass with enlarged mediastinal lymph nodes but no focal bony lesions. Serum levels of which of the following substances are most likely to be elevated in this patient?

Question

A 65-year-old woman is brought to the emergency department due to progressive lethargy and generalized weakness. She has also had loss of appetite, constipation, muscle weakness, and increased thirst and urination. The patient's medical history is unremarkable. She takes no prescription medications. The patient does not use tobacco, alcohol, or illicit drugs. On physical examination, she is stuporous and has dry mucous membranes. Laboratory testing shows serum calcium of 14.0 mg/dL and normal serum glucose and urinalysis.  Imaging studies reveal an 8-cm right lung mass with enlarged mediastinal lymph nodes but no focal bony lesions.  Serum levels of which of the following substances are most likely to be elevated in this patient?

Quizplus · Accepted Answer

Eductional Objective: Serum calcium >13 mg/dL is suggestive of an underlying malignancy.  Secretion of parathyroid hormone-related protein (PTHrP), which closely resembles parathyroid hormone at the bioactive amino-terminal region, is a frequent cause of malignancy-related hypercalcemia and is commonly seen with squamous cell carcinomas (eg, lung, neck).

A 65-Year-Old Woman Is Brought to the Emergency Department Due