title: Long-term bone loss in kidney transplant recipients: a cross-sectional and longitudinal study.
abstract: Organ transplantation is associated with an early bone loss that subsequently increases the risk of osteopenia and bone fractures. It is not known whether bone loss continues in long-term survivors, but persistent bone demineralization could further jeopardize an already diminished bone mass. To better define long-term bone status of kidney transplant recipients (KTR), we conducted cross-sectional and longitudinal evaluations of bone mineral density (BMD) in 70 KTR with a mean posttransplantation time of 8.1 years. BMD was determined by dual-energy X-ray absorptiometry and was repeated in 55 of the patients after a mean follow-up period of 22 +/- 5 months. Lumbar and femoral osteopenia, defined as a BMD lower than 2 standard deviations from mean value of sex- and age-matched controls, was present in 28.6% and 10.5% of patients, respectively. There was a significant negative correlation between cumulative prednisone dose and adjusted lumbar as well as femoral BMD (R = 0.45, P < 0.001 and R = 0.29, P < 0.05, respectively). Five patients had a vertebral BMD below a fracture threshold of 0.777 g/cm2. Vertebral fractures (VF) were found in four men and were associated with higher prednisone dosage (P < 0.05), larger cumulative prednisone dose (P < 0.05), and significantly lower BMD values. According to World Health Organization recent criteria for women, prevalences of lumbar and femoral osteopenia and lumbar and femoral osteoporosis in female patients reach 75%, 65%, 33%, and 10%, respectively. The longitudinal part of the study showed a persistent pathological lumbar demineralization process. Over the study period, BMD, expressed as a percentage of that of controls, decreased from 89 +/- 14% to 86 +/- 14% (P < 0.001). Annual change of bone mass was -1.7 +/- 2.8% per year. Accelerated vertebral bone loss (defined as a decrease of BMD, expressed as a percentage of that of controls, of more than 1% per year) was present in 56% of patients and was associated with higher prednisone dosage (P < 0.01). In conclusion, although VF are relatively infrequent in long-term survivors of renal transplantation, osteopenia is a frequent finding, and a substantial proportion of women present lumbar osteoporosis. An ongoing demineralization process of the spine is also demonstrated and probably contributes to long-term spinal osteoporosis incidence. Prednisone dosage remains the most constantly isolated risk factor.
authors.affiliation: Medical Research Council of Canada, Montréal, Québec, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Pichette
authors.forename: A
authors.initials: A
authors.lastname: Bonnardeaux
authors.forename: L
authors.initials: L
authors.lastname: Prudhomme
authors.forename: M
authors.initials: M
authors.lastname: Gagné
authors.forename: J
authors.initials: J
authors.lastname: Cardinal
authors.forename: D
authors.initials: D
authors.lastname: Ouimet
mesh_terms: D000328:Adult; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D005938:Glucocorticoids / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D016030:Kidney Transplantation; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011241:Prednisone / Q000008:administration & dosage / Q000009:adverse effects*; D015995:Prevalence; D012307:Risk Factors; D016103:Spinal Fractures / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D013997:Time Factors
chemical_list: D005938:Glucocorticoids; D011241:Prednisone