A 55-year-old man comes to the physician because of a one-month history of increased urination and thirst. Serum sodium is 147 mg/dL. Urine specific gravity is 1.003. A nomogram of the patient’s serum PTH and calcium levels is shown below.
Which of the following is the most likely mechanism for this patient’s findings as exhibited by the nomogram?
Diabetes insipidus
Diabetes mellitus
Osteomalacia
Metastatic malignancy
Paget disease
Primary hypoparathyroidism
