Increase in Lumbar Spine Bone Mineral Content in Patients on Long-Term Parenteral Nutrition Without Vitamin D Supplementation

Abstract

Background: We had previously shown that short-term withdrawal of vitamin D in patients with metabolic bone disease complicating home parenteral nutrition (HPN) corrected osteomalacia. We therefore conducted a prospective study of the effect of long term withdrawal of vitamin D in patients on home parenteral nutrition. Methods: Baseline measurements of bone mineral content, serum levels of calcium, phosphorus, parathormone, 25-OH and 1,25 (OH)₂ D; urinary calcium; and bone mineral density were measured. Then all parenteral vitamin D was withdrawn and the above parameters were followed for a mean of 4.5 years. Results: Lumbar spine bone mineral content (LSBMC) was 0.79 ± 0.06 g/cm² at the start of the study, well below the reference value, 1.16 ± 0.13 g/cm². Parathyroid hormone (PTH) (0.48 ± 0.24 pmol/L) and 1,25-(OH)₂D levels (22.8 ± 7.9 pmol/L) were low and 25-hydroxyvitaniin D levels were normal (33.3 ± 5.5 nmol/L) before removing vitandn D from the HPN solutions. After withdrawal of vitamin D for 4.5 ± 0.2 years LSBMC increased from 0.79 ± 0.06 to 0.93 0.07 g/cm2 (p < 0.005). Calcium phosphorus, magnesium and 25-hydroxyvitamin D did not change significantly, 1,25(OH)2D, and PTH levels became normal after withdrawal of vitamin D. Conclusions: In selected patients with depressed PTH levels, long-term withdrawal of vitamin D during HPN increases LSBMC and levels of PTH and 1,25(OH)2D. There is no reduction of the mean level of 25-hydroxyvitamin D. (Journal of Parenteral and Enteral Nutrition 19:431-436, 1995)