This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Secondary hyperparathyroidism is seen in all EXCEPT: 
Select and explain. 
A. Chronic renal failure, B. Vitamin D deficiency, C. Medullary carcinoid syndrome, D. Adenoma
D: Adenoma
Answer: D: Adenoma 
Explanation: Adenoma REF: Harrison's 17' ed p. 2388 Causes of secondary hyperparathyroidism Chronic renal failure Malabsorption syndrome Vitamin D deficiency Medullary carcinoma thyroid