This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
Increased Ca, decreased PO^ Diagnosis is- 
Select and explain. 
A. Primary' hyperparathyroidism, B. Secondary hyperparathyroidism due to Vit D deficiency, C. Malignancy, D. Osteoporosis
A: Primary' hyperparathyroidism
Answer: A: Primary' hyperparathyroidism 
Explanation: Ans. is 'a' i.e., Primary hyperparathyroidism Differential diagnosis of various conditions based on Key test results Serum CaSerum phosphrousAlkaline phosphrousPTHo Osteomalacia (Rickets) (Vit. D)||||o Primary hyperparathyroidism bone diseaseT|T|o Bone disease in renal failure with secondary hyperparathyroidismN||||o Lytic bone neoplasmsN/|N/|N/|No OsteoporosisNNNNo Paget's diseaseNN|N