Bone Deterioration After Kidney Transplantation Assessed by DXA and HR-pQCT (DXACT)
Prospective Imaging-based Assessment of Skeletal Deterioration After Kidney Transplantation Using DXA and HR-pQCT (DXACT Study)
The goal of this observational study is to learn how bone health changes during the first year after kidney transplantation in adults receiving their first kidney transplant.
The main questions it aims to answer are:
- How many patients show a clinically relevant decline in bone density or bone structure within 12 months after transplantation?
- Does a standard bone density scan (DXA) detect these changes as well as a high-resolution scan of bone structure (HR-pQCT)?
Participants will:
- Have a DXA scan of the lower spine, hip and forearm and an HR-pQCT scan of the forearm and lower leg shortly after transplantation and again after 12 months. Participants followed up in Innsbruck may also have these scans after 6 months.
- Give blood and urine samples at the same visits, taken together with routine blood tests whenever possible, for bone and mineral markers and storage in a biobank.
The study does not change any treatment. All treatment decisions remain with the patients' physicians.
Descripción general del estudio
Estado
Condiciones
Intervención / Tratamiento
Descripción detallada
Bone mineral density declines rapidly during the first 6-12 months after kidney transplantation, driven by glucocorticoid exposure, persistent chronic kidney disease-mineral and bone disorder (CKD-MBD) and changes in bone turnover. This period coincides with the highest fracture risk. DXA-scans provide areal bone mineral density only and cannot distinguish cortical from trabecular bone or assess microarchitecture, so it may underestimate early cortical deterioration. HR-pQCT measures volumetric bone mineral density, cortical and trabecular microarchitecture and, by finite element analysis, estimated bone strength.
DXACT is an investigator-initiated, prospective, single-centre observational cohort study at the Medical University of Innsbruck. Baseline clinical and laboratory assessment is performed 7 +/- 2 days and imaging 10 +/- 7 days after transplantation; assessments are repeated at 12 months, with an optional 6-month visit for participants followed locally. HR-pQCT is performed at the distal radius and distal tibia of the dominant side (contralateral side if a vascular access or implant is present); DXA at the lumbar spine (L1-L4), hip and distal radius (33%).
Clinically relevant skeletal deterioration is defined as a change exceeding the least significant change (LSC = 2.77 x precision CV) of the respective modality and parameter. Laboratory assessments include parathyroid hormone, 25-hydroxy- and 1,25-dihydroxyvitamin D, calcium, phosphate, P1NP, bone-specific alkaline phosphatase, TRAP5b, CTX, osteocalcin and osteoprotegerin. EDTA plasma and urine are stored in a pseudonymised biobank at -80 °C.
Analyses are primarily descriptive and exploratory. Planned analyses include agreement and discordance between DXA- and HR-pQCT-based classification, associations of imaging changes with biochemical markers and clinical factors (age, sex, dialysis vintage, cumulative glucocorticoid dose, rejection, graft function), and comparison by graft function at 12 months. Incident fragility fractures beyond 12 months may be retrieved from routine clinical records without further participant contact.
Tipo de estudio
Inscripción (Estimado)
Contactos y Ubicaciones
Estudio Contacto
- Nombre: Clemens Untersulzner, MD
- Número de teléfono: +43 50504 84848
- Correo electrónico: clemens.untersulzner@i-med.ac.at
Copia de seguridad de contactos de estudio
- Nombre: Andreas Kronbichler, MD, PhD
- Número de teléfono: +43 50504 25855
- Correo electrónico: andreas.kronbichler@i-med.ac.at
Ubicaciones de estudio
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Tyrol
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Innsbruck, Tyrol, Austria, 6020
- Reclutamiento
- Medical University of Innsbruck, Department of Internal Medicine IV, Nephrology and Hypertension
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Contacto:
- Clemens Untersulzner, MD
- Número de teléfono: +43 50504 84848
- Correo electrónico: clemens.untersulzner@i-med.ac.at
-
Contacto:
- Andreas Kronbichler, MD, PhD
- Número de teléfono: +43 50504 25855
- Correo electrónico: andreas.kronbichler@i-med.ac.at
-
Investigador principal:
- Andreas Kronbichler, MD, PhD
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Sub-Investigador:
- Clemens Untersulzner, MD
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Criterios de participación
Criterio de elegibilidad
Edades elegibles para estudiar
Acepta Voluntarios Saludables
Géneros elegibles para el estudio
Método de muestreo
Población de estudio
Adult recipients of a first kidney transplant (living or deceased donor) treated at the Medical University of Innsbruck, Austria, who are approached by the study team within 10 days after transplantation.
Descripción
Inclusion Criteria:
- Age 18 years or older at the time of kidney transplantation
- First kidney transplantation (living or deceased donor)
- Ability and willingness to provide written informed consent
- Enrolment possible within 10 days after kidney transplantation
- Clinical stability sufficient to undergo imaging procedures
Exclusion Criteria:
- Previous kidney transplantation
- Prior or ongoing treatment with antiresorptive or osteoanabolic therapies (e.g. bisphosphonates, denosumab, teriparatide) at the time of transplantation
- Conditions precluding reliable bone imaging, including metal implants at the measurement sites
- Contraindications to HR-pQCT or DXA
- Inability to undergo imaging due to physical or technical limitations
- Known metabolic bone diseases unrelated to chronic kidney disease-mineral and bone disorder (CKD-MBD)
- Any condition that, in the opinion of the investigator, would interfere with study participation, data quality or protocol adherence
Plan de estudios
¿Cómo está diseñado el estudio?
Detalles de diseño
- Modelos observacionales: COHORT
- Perspectivas temporales: PROSPECTIVE
Cohortes e Intervenciones
Grupo / Cohorte |
Intervención / Tratamiento |
|---|---|
|
Kidney transplant recipients
Adults (18 years or older) who received a first kidney transplant (living or deceased donor) at the Medical University of Innsbruck and are enrolled within 10 days after transplantation. |
Dual-energy X-ray absorptiometry of the lumbar spine (L1-L4), hip and distal radius (33%) and high-resolution peripheral quantitative computed tomography of the distal radius and distal tibia, performed at baseline (10 +/- 7 days after kidney transplantation) and at 12 months, with an optional 6-month visit. Imaging is used for research only; no treatment is assigned.
Otros nombres:
Blood and urine samples at each study visit, taken together with routine blood draws, for markers of bone and mineral metabolism and storage in a biobank. |
¿Qué mide el estudio?
Medidas de resultado primarias
Medida de resultado |
Medida Descripción |
Periodo de tiempo |
|---|---|---|
|
Proportion of Participants With Clinically Relevant Skeletal Deterioration on HR-pQCT
Periodo de tiempo: Baseline (10 +/- 7 days after transplantation) to 12 months
|
Deterioration exceeding the least significant change (LSC = 2.77 x precision CV) in at least one of cortical thickness, cortical porosity or finite element-derived failure load at the distal radius or distal tibia. |
Baseline (10 +/- 7 days after transplantation) to 12 months
|
|
Proportion of Participants With Clinically Relevant Skeletal Deterioration on DXA
Periodo de tiempo: Baseline (10 +/- 7 days after transplantation) to 12 months
|
Decrease in areal bone mineral density exceeding the site-specific least significant change at the lumbar spine (L1-L4), hip or distal radius (33%). |
Baseline (10 +/- 7 days after transplantation) to 12 months
|
Medidas de resultado secundarias
Medida de resultado |
Medida Descripción |
Periodo de tiempo |
|---|---|---|
|
Change in Cortical Thickness
Periodo de tiempo: Baseline to 12 months
|
Absolute (mm) and relative (%) change in cortical thickness at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Cortical Porosity
Periodo de tiempo: Baseline to 12 months
|
Absolute (percentage points) and relative change in cortical porosity at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Total Volumetric BMD
Periodo de tiempo: Baseline to 12 months
|
Absolute (mg HA/cm³) and relative (%) change in total volumetric bone mineral density at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Cortical Volumetric BMD
Periodo de tiempo: Baseline to 12 months
|
Absolute (mg HA/cm³) and relative (%) change in cortical volumetric bone mineral density at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Trabecular Volumetric BMD
Periodo de tiempo: Baseline to 12 months
|
Absolute (mg HA/cm³) and relative (%) change in trabecular volumetric bone mineral density at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Trabecular Number
Periodo de tiempo: Baseline to 12 months
|
Absolute (1/mm) and relative (%) change in trabecular number at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Trabecular Thickness
Periodo de tiempo: Baseline to 12 months
|
Absolute (mm) and relative (%) change in trabecular thickness at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Trabecular Separation
Periodo de tiempo: Baseline to 12 months
|
Absolute (mm) and relative (%) change in trabecular separation at the distal radius and distal tibia measured by HR-pQCT. |
Baseline to 12 months
|
|
Change in Biochemical Markers of Bone and Mineral Metabolism
Periodo de tiempo: Baseline to 12 months
|
Change in parathyroid hormone, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, calcium, phosphate, P1NP, bone-specific alkaline phosphatase, TRAP5b, CTX, osteocalcin and osteoprotegerin |
Baseline to 12 months
|
|
Change in Estimated Bone Strength (Failure Load)
Periodo de tiempo: Baseline to 12 months
|
Absolute and relative change in finite element-derived failure load (N) at the distal radius and distal tibia. |
Baseline to 12 months
|
|
Change in Areal Bone Mineral Density
Periodo de tiempo: Baseline to 12 months
|
Absolute and relative change in areal BMD (g/cm2) at the lumbar spine (L1-L4), total hip, femoral neck and distal radius (33%) measured by DXA. |
Baseline to 12 months
|
|
Skeletal Changes by Graft Function
Periodo de tiempo: 12 months
|
Comparison of HR-pQCT and DXA changes between participants with eGFR >= 60 and < 60 mL/min/1.73 m2 (CKD-EPI 2021) at 12 months. |
12 months
|
Otras medidas de resultado
Medida de resultado |
Medida Descripción |
Periodo de tiempo |
|---|---|---|
|
Discordance Between DXA and HR-pQCT Classification
Periodo de tiempo: 12 months
|
Proportion of participants classified differently by DXA and HR-pQCT, in particular stable DXA with deterioration on HR-pQCT. |
12 months
|
|
Association of Dialysis Vintage With Skeletal Deterioration
Periodo de tiempo: Baseline to 12 months
|
Pre-transplant dialysis duration (continuous; pre-emptive, < 12, >= 12 months) as predictor of imaging-derived skeletal changes. |
Baseline to 12 months
|
|
Incident Fragility Fractures
Periodo de tiempo: Up to 5 years after transplantation
|
Fragility fractures retrieved from routine clinical records without participant contact. |
Up to 5 years after transplantation
|
Colaboradores e Investigadores
Patrocinador
Investigadores
- Investigador principal: Andreas Kronbichler, MD, PhD, Medical University Innsbruck
Publicaciones y enlaces útiles
Publicaciones Generales
- Jorgensen HS, Behets G, Bammens B, Claes K, Meijers B, Naesens M, Sprangers B, Kuypers DRJ, Cavalier E, D'Haese P, Evenepoel P. Natural History of Bone Disease following Kidney Transplantation. J Am Soc Nephrol. 2022 Mar;33(3):638-652. doi: 10.1681/ASN.2021081081. Epub 2022 Jan 19.
- Evenepoel P, Claes K, Meijers B, Laurent MR, Bammens B, Naesens M, Sprangers B, Pottel H, Cavalier E, Kuypers D. Bone mineral density, bone turnover markers, and incident fractures in de novo kidney transplant recipients. Kidney Int. 2019 Jun;95(6):1461-1470. doi: 10.1016/j.kint.2018.12.024. Epub 2019 Mar 4.
- Untersulzner C, Pirklbauer M, Evenepoel P, Zoller H, Kronbichler A. Bone Mineral Density Loss After Kidney Transplantation: Metabolic Determinants, Diagnostic Approaches, and Preventive Strategies. Kidney Int Rep. 2026 Jun 30;11(9):106685. doi: 10.1016/j.ekir.2026.106685. eCollection 2026 Sep.
Fechas de registro del estudio
Fechas importantes del estudio
Inicio del estudio (Actual)
Finalización primaria (Estimado)
Finalización del estudio (Estimado)
Fechas de registro del estudio
Enviado por primera vez
Primero enviado que cumplió con los criterios de control de calidad
Publicado por primera vez (Actual)
Actualizaciones de registros de estudio
Última actualización publicada (Actual)
Última actualización enviada que cumplió con los criterios de control de calidad
Última verificación
Más información
Términos relacionados con este estudio
Palabras clave
Términos MeSH relevantes adicionales
- Enfermedades urogenitales
- Enfermedades del sistema endocrino
- Enfermedades musculoesqueléticas
- Procesos Patológicos
- Trastornos Nutricionales
- Enfermedades urogenitales masculinas
- Enfermedades Renales
- Enfermedades urológicas
- Enfermedades urogenitales femeninas
- Enfermedades urogenitales femeninas y complicaciones del embarazo
- Enfermedad crónica
- Atributos de la enfermedad
- Enfermedades metabólicas
- Enfermedades de las paratiroides
- Avitaminosis
- Enfermedades por deficiencia
- Desnutrición
- Raquitismo
- Trastornos del metabolismo del calcio
- Deficiencia de vitamina D
- Hiperparatiroidismo Secundario
- Hiperparatiroidismo
- Condiciones Patológicas, Signos y Síntomas
- Enfermedades Nutricionales y Metabólicas
- Osteoporosis
- Enfermedades óseas
- Enfermedades Óseas Metabólicas
- Enfermedad renal crónica: trastorno mineral y óseo
- Técnicas de investigación
- Manejo de muestras
- Técnicas de laboratorio clínico
- Técnicas y procedimientos de diagnóstico
- Diagnóstico
- Puntas
- Procedimientos quirúrgicos, operativo
- Imágenes de diagnóstico
- Técnicas de química, analítica
- Radiografía
- Densitometría
- Fotometría
- Absorptiometría, fotón
- Recolección de muestras de sangre
Otros números de identificación del estudio
- DXACT-003
- 1140/2026 (Otro identificador: Ethics Committee of the Medical University of Innsbruck)
Plan de datos de participantes individuales (IPD)
¿Planea compartir datos de participantes individuales (IPD)?
Descripción del plan IPD
Individual participant data will not be shared publicly, as participant consent does not cover transfer to third parties. De-identified data may be made available by the study lead upon reasonable request, subject to approval by the ethics committee and data protection regulations.
Información sobre medicamentos y dispositivos, documentos del estudio
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Estudia un producto de dispositivo regulado por la FDA de EE. UU.
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