title: Increased bone turnover is associated with protein and energy metabolism in adolescents with sickle cell anemia.
abstract: Contribution of bone turnover to the hypercatabolic state observed in sickle cell anemia is unknown. We examined the association between markers of bone turnover and basal rates of whole body protein turnover and energy expenditure in 28 adolescents with homozygous sickle cell anemia (HbSS) and in 26 matched controls with normal phenotype (HbAA). Whole body protein breakdown and synthesis were measured using a stable isotope of [15N]glycine, resting energy expenditure was measured by whole room indirect calorimetry, and the rate of pyridinoline cross-link (PYD) excretion in urine and fasting serum levels of the type I procollagen carboxy-terminal propeptide (PICP) were measured with commercial kits. Urinary PYD and serum PICP were significantly elevated in HbSS patients. The increase in procollagen synthesis, indicated by high levels of PICP, was significantly correlated with increased whole body protein synthesis. The increase in type I collagen degradation, indicated by high PYD excretion, was significantly correlated with increased protein breakdown. We conclude that increased rates of bone turnover contribute to the increased rates of protein turnover and energy expenditure observed in adolescents with homozygous sickle cell anemia.
authors.affiliation: Center for Nutrition and Department of Family Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Buchowski
authors.forename: F A
authors.initials: FA
authors.lastname: de la Fuente
authors.forename: P J
authors.initials: PJ
authors.lastname: Flakoll
authors.forename: K Y
authors.initials: KY
authors.lastname: Chen
authors.forename: E A
authors.initials: EA
authors.lastname: Turner
mesh_terms: D000293:Adolescent; D000755:Anemia, Sickle Cell / Q000503:physiopathology*; D015415:Biomarkers / Q000032:analysis; D016723:Bone Remodeling; D002153:Calorimetry, Indirect; D003094:Collagen / Q000378:metabolism / Q000652:urine; D024042:Collagen Type I; D004734:Energy Metabolism; D005260:Female; D005998:Glycine / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008297:Male; D009587:Nitrogen Isotopes; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides / Q000652:urine; D011347:Procollagen / Q000096:biosynthesis / Q000097:blood; D011506:Proteins / Q000378:metabolism*; D012044:Regression Analysis
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D009587:Nitrogen Isotopes; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; D011506:Proteins; C052929:collagen type I trimeric cross-linked peptide; C042813:procollagen type I carboxy terminal peptide; D003094:Collagen; D005998:Glycine