Normal total and ionized Ca and high PTH at first visit. 25(OH)D ≥ 20 ng/ml (patients with low vitamin D were treated, and PTH had to be elevated after retest at 3 mo). Excluded cases with renal insufficiency, Ca malabsorption, hypercalciuria, medications (PPI, thiazides, lithium). Here, PTH is linked to Renal insufficiency.