title: Calcium deficiency-induced secondary hyperparathyroidism and osteopenia are rapidly reversible with calcium supplementation in growing rabbit pups.
abstract: The reversibility of osteopenia secondary to isolated Ca deficiency (CaDef) is still not clear. We studied the effect of severe CaDef on Ca homeostasis and bone accrual in a 'hypercalcaemic' animal, the rabbit, during the post-weaning period and its reversibility on Ca supplementation. Male Belgian 5-week-old rabbit pups were fed CaDef diet (0.026 % Ca) for 10 weeks. As compared with those fed with a normal chow diet (0.45 % Ca), CaDef pups developed significant hypocalcaemia (P < 0.05), hypocalciuria (urinary Ca 76 (SEM 12) v. 17 (SEM 1) mg/l; P < 0.005), hypophosphataemia (serum inorganic P 100 (SEM 6) v. 65 (SEM 4) mg/l; P < 0.005), secondary hyperparathyroidism (SHPT) (serum intact parathyroid hormone human equivalent 18.2 (SEM 1.4) v. 125.0 (SEM 4.5) pg/ml; P < 0.001) and elevated serum calcitriol levels (34.0 (SEM 3.9) v. 91.0 (SEM 1.0) pg/ml; P < 0.005). Elevated urinary C-terminal telopeptide of class I collagen (P < 0.005) and total serum alkaline phosphatase (P < 0.005) suggested increased bone turnover. There was a significantly lower gain in bone mineral density (BMD) and bone mineral content (BMC) in the whole body and lumbar spine in vivo, and various sub-regions of the femur and tibia in vitro. Supplementation of adequate Ca (0.45 % Ca) after 15 weeks on the normal diet resulted in rapid catch-up growth, and resolution of SHPT. Rapid gain in various BMD and BMC parameters continued at 30 weeks of age, and both were comparable with those in rabbits on a normal diet. We conclude that Ca deficiency-induced SHPT and poor bone accrual in growing rabbit pups are rapidly reversible with Ca supplementation. The present study indicates that early intervention may be a more appropriate window period for human nutritional corrective measures.
authors.affiliation: Department of Medical Endocrinology, Centre for Endocrine Sciences, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Meenal
authors.initials: M
authors.lastname: Mehrotra
authors.forename: Sushil K
authors.initials: SK
authors.lastname: Gupta
authors.forename: Krishan
authors.initials: K
authors.lastname: Kumar
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Awasthi
authors.forename: Manoj
authors.initials: M
authors.lastname: Dubey
authors.forename: Chandra M
authors.initials: CM
authors.lastname: Pandey
authors.forename: Madan M
authors.initials: MM
authors.lastname: Godbole
mesh_terms: D000469:Alkaline Phosphatase / Q000652:urine; D000818:Animals; D015519:Bone Density / Q000187:drug effects / Q000502:physiology; D001851:Bone Diseases, Metabolic / Q000178:diet therapy* / Q000209:etiology; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood / Q000172:deficiency*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D003094:Collagen / Q000652:urine; D024042:Collagen Type I; D019587:Dietary Supplements; D006962:Hyperparathyroidism, Secondary / Q000178:diet therapy / Q000209:etiology*; D006996:Hypocalcemia / Q000178:diet therapy / Q000209:etiology; D017674:Hypophosphatemia / Q000178:diet therapy / Q000209:etiology; D008297:Male; D010455:Peptides / Q000652:urine; D011817:Rabbits; D011897:Random Allocation; D015430:Weight Gain / Q000187:drug effects / Q000502:physiology
chemical_list: D002136:Calcium, Dietary; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen; D000469:Alkaline Phosphatase; D002117:Calcitriol; D002118:Calcium