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Abstract: SA-PO317

Bone Disease Related to Severe Vitamin D Deficiency in an Adult

Session Information

Category: Bone and Mineral Metabolism

  • 502 Bone and Mineral Metabolism: Clinical

Authors

  • Singh, Amandeep, University of Kentucky College of Medicine, Lexington, Kentucky, United States
  • Rao, Madhumathi, University of Kentucky College of Medicine, Lexington, Kentucky, United States
  • Cassidy, Carter, University of Kentucky Medical Center, Lexington, Kentucky, United States
  • Malluche, Hartmut H., University of Kentucky College of Medicine, Lexington, Kentucky, United States
Introduction

Severe vitamin D deficiency (VDD) as a cause of bone disease is seen very rarely. While VDD can cause osteomalacia, associated secondary hyperparathyroidism (HPT) can also produce significant histopathological changes in the bone.

Case Description

A 60-year-old post-menopausal Caucasian woman, was admitted with a left subtrochanteric femur fracture in 2021, following a ground-level fall and underwent ORIF. She has had prior vertebral fractures, stage 3A CKD, and 30 pack year smoking history. Laboratory data revealed vitamin D (VD) <6.5 ng/ml, iPTH 492 pg/ml, calcium 7.9 mg/dl, ALP 602 U/l and BSAP >120 ug/l. Albumin, phosphorus, creatinine, and eGFR were 4.2 g/l, 2.9 mg/dl, 1.0 mg/dl, and 50ml/min, respectively. Imaging indicated diffuse sclerosis of the spine. Whole-body bone scintigraphy showed diffuse increased uptake throughout the skeleton in a "super scan" pattern. Forearm bone density showed a T-score of -2.6. Undecalcified bone biopsy of the iliac crest with double tetracycline labeling revealed a mixed pattern with high turnover, low mineralization and increased bone volume with areas of woven bone, with diffuse single labels on fluorescent microscopy (image). Malabsorption workup was inconclusive. Aggressive vitamin D replacement over a year, resulted in progressive normalization of VD, iPTH and BSAP levels, and improvement in radiological sclerosis.

Discussion

This patient presented with severe VDD in the setting of multiple fractures, with severe secondary HPT, bony sclerosis and renal osteodystrophy. The severity of HPT was out of proportion to her CKD and caused by VDD. Aggressive treatment with vitamin D resulted in marked reversal of bone abnormalities. With a fourth of the US population estimated to have VDD (<20ng/mL), it is important to consider VDD as a treatable secondary cause of and contributor to bone disease and fracture.

(Left) Femur fracture with varus angulation, increased sclerosis of the spine. (Center) Undecalcified bone biopsy (Masson-Goldner trichrome, 20x) showing mixed osteodystrophy with unmineralized osteoid, osteoblasts and multinucleate osteoclasts. (Right) Fluorescent microscopy (2.5x) showing isolated single labels with diffuse tetracycline deposition.