Renal osteopathy (renal osteodystrophy) is a collective name for the skeletal changes within the complex disorder of phosphocalcium metabolism that occur in chronic kidney disease. Today it is classified among the three components of CKD-MBD (bone and mineral disorder in chronic kidney disease). The clinical picture is very multifaceted due to the fact that individual factors apply to each patient at a given time in different intensity. Manifestations include osteopenia, osteomalacia, secondary hyperparathyroidism and growth retardation.
Pathogenesis[edit | edit source]
Skeletal changes are caused in renal failure by three mechanisms:
Tubular Dysfunction[edit | edit source]
Low pH due to renal acidosis unbinds calcium and phosphorus ions from the hydroxyapatite structure. This results in demineralization of the bone matrix and osteomalacia.
Generalized renal failure[edit | edit source]
It leads to a decrease in phosphate excretion due to insufficient renal elimination, thus creating chronic hyperphosphatemia. Hyperphosphatemia stimulates the parathyroid glands, which contributes to secondary hyperparathyroidism.
Decreased production of enzymes and growth factors[edit | edit source]
The kidneys secrete an enzyme (1-hydroxylase) that converts vitamin D into an active form and also secrete the protein BMP-7. A decrease in active vitamin D3 (calcitriolu) leads to hypocalcemia and contributes to secondary hyperparathyroidism. Calcitriol deficiency increases the secretion of parathyroid hormone (PTH), which activates 1-hydroxylase, thereby adjusting the level of calcitriol in the blood, but hyperparathyroidism occurs. However, with progressive failure, this compensatory mechanism is insufficient and hypocalcemia occurs. BMP-7 produced by renal tubular cells induces osteoblast proliferation and differentiation. Its reduced production thus leads to osteopenia.
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References[edit | edit source]
- KUMAR, [edited by] Vinay – KUMAR, Vinay – PERKINS, Jon C. Aster ; with illustrations by James A. Robbins and Cotran pathological basis of disease. 9. edition. Philadelphia : Elsevier Saunders, c2015. ISBN 9781455726134.
- VIKRANT, Sanjay – PARASHAR, Anupam. Prevalence and severity of disordered mineral metabolism in patients with chronic kidney disease: A study from a tertiary care hospital in India. Indian J Endocrinol Metab [online]. 2016 Jul-Aug, vol. 20, no. 4, p. 460-7, Available from <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4911834/?tool=pubmed>. ISSN 2230-9500 (print), 2230-8210.