Pediatr Nephrol (2008) 23:195–207 Answers 1. a (10–65 pg/ml) 2. b (initiate calcium-free phosphate binder) 3. b (after correction of acidosis, anemia and secondary hyperparathyroidism) 4. b (nutritional assessment and phosphate restriction) 5. b (height 50% for age) 6. c (switching to non-calcium phosphate binder) 7. a (serum PTH 900 pg/ml) 8. c (add sevelamer) 9. b (lanthanum carbonate) 207