A 58-year-old female presents with muscle weakness and fatigue. Blood tests show high calcium levels and a slightly decreased creatinine clearance. What are the potential diagnoses and next steps?
Hypercalcemia and impaired kidney function, along with the symptoms of muscle weakness and fatigue, could suggest primary hyperparathyroidism or a malignancy, as both can result in elevated calcium levels. Another possibility is sarcoidosis, which can cause increased calcium absorption. The next steps should be parathyroid hormone (PTH) measurement, vitamin D levels, a thorough medication review, and imaging to rule out malignancy.