A 44-year-old male presents to his primary care physician with complaints of fatigue, muscle weakness, cramps, and increased urination over the past several weeks. His past medical history is significant only for hypertension, for which he was started on hydrochlorothiazide (HCTZ) 4 weeks ago. Vital signs at today's visit are as follows: T 37.2, HR 88, BP 129/80, RR 14, and SpO2 99%. Physical examination does not reveal any abnormal findings. Serologic studies are significant for a serum potassium level of 2.1 mEq/L (normal range 3.5-5.0 mEq/L). Lab-work from his last visit showed a basic metabolic panel and complete blood count results to all be within normal limits. Which of the following underlying diseases most likely contributed to the development of this patient's presenting condition?