FGF23 is regulated at the transcriptional and posttranscriptional levels by several bone mineral factors, including phosphate (via glycerol-3-phosphate and lysophosphatidic acid) (9, 10), calcium, vitamin D, and parathyroid hormone (PTH) (11), and nonmineral factors like anemia, inflammation, and metabolism (12). The gene discussed is PTH; the disease is anemia.