Clearance of 25-hydroxyvitamin D in Cystic Fibrosis

Exclusion Criteria

• •Primary hyperparathyroidism
• •Gastric bypass
• •Tuberculosis or sarcoidosis
• •Current pregnancy
• •Child-Pugh Class B or C cirrhosis (i.e. cirrhosis with ascites, hepatic encephalopathy, bilirubin \>=2 mg/dL, serum albumin \<=3.5 g/dL, or PT \>= 4 seconds)
• •History of kidney transplantation or end stage renal disease treated with dialysis
• •Use of vitamin D3 or vitamin D2 supplements exceeding a mean daily dose of 400 IU, within 3 months (wash-out allowed)
• •Use of 1,25(OH)2D3 or an analogue, calcimimetics, or medications known to induce CYP24A1 within 4 weeks (wash-out allowed)
• •Serum calcium \> 10.1 mg/dL
• •Hemoglobin \< 9 g/dL