Vitamin D metabolism and osteomalacia in cystic fibrosis

Gastroenterology. 1985 Mar;88(3):808-13. doi: 10.1016/0016-5085(85)90156-8.

Abstract

A 25-yr-old black man with cystic fibrosis and cirrhosis developed symptoms of osteomalacia and hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and low circulating 25-hydroxyvitamin D (25-OHD). Serum 1,25-dihydroxyvitamin D (1,25-[OH]2D) was within the normal range. Iliac crest bone biopsy confirmed the diagnosis of osteomalacia. Oral administration of 50,000 IU of vitamin D2 failed to relieve symptoms or raise serum 25-OHD levels to normal. Intramuscular vitamin D2, 10,000 IU every 8-12 week, improved symptoms, raised serum 25-OHD to normal, and increased circulating 1,25-[OH]2D to values five times normal. Over the next 10 mo circulating 1,25-[OH]2D remained elevated despite normalization of serum calcium, phosphorus, and parathyroid hormone. Repeat bone biopsy 1 yr after parenteral vitamin D showed healing of the osteomalacia. Malabsorption of vitamin D appears secondary to profound steatorrhea due to pancreatic insufficiency and secondary biliary cirrhosis. Although extensive hepatocellular disease was present, hepatic conversion of vitamin D to 25-OHD was intact. Both high and low circulating 1,25-[OH]2D levels during active osteomalacia have been reported; initially, the level was in the normal range and higher values in this patient occurred with repletion of 25-OHD substrate. This study shows that symptomatic osteomalacia may be a major manifestation of cystic fibrosis in those patients surviving into adulthood. Measurements of serum 25-OHD in cystic fibrosis patients may identify those who should receive supplemental vitamin D.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Bone and Bones / pathology
  • Calcium / metabolism
  • Cystic Fibrosis / drug therapy
  • Cystic Fibrosis / metabolism*
  • Ergocalciferols / therapeutic use
  • Humans
  • Hydroxycholecalciferols / blood
  • Hyperparathyroidism, Secondary / metabolism
  • Hypocalcemia / metabolism
  • Liver / metabolism
  • Liver Cirrhosis / metabolism
  • Magnesium / metabolism
  • Malabsorption Syndromes / metabolism
  • Male
  • Osteomalacia / drug therapy
  • Osteomalacia / metabolism*
  • Parathyroid Hormone / blood
  • Phosphorus / blood
  • Serum Albumin / analysis
  • Vitamin D / metabolism*

Substances

  • Ergocalciferols
  • Hydroxycholecalciferols
  • Parathyroid Hormone
  • Serum Albumin
  • Vitamin D
  • Phosphorus
  • Magnesium
  • Calcium