ABS0172 HOW RELIABLE ARE THE ADRAR AND MAC KENNA INDICES IN DIAGNOSING OSTEOMALACIA INSIGHTS FROM A RETROSPECTIVE STUDY

Abstract

<h2>Abstract</h2><h3>Background:</h3> Osteomalacia is a rare metabolic bone disorder characterized by defective bone mineralization, resulting in increased bone fragility and diffuse musculoskeletal pain. It is commonly associated with vitamin D deficiency and abnormalities in calcium and phosphorus metabolism. Due to its nonspecific clinical presentation, diagnosing osteomalacia can be challenging. To improve diagnostic accuracy, indices such as the Adrar and Mac Kenna have been proposed as tools for confirming the diagnosis. <h3>Objectives:</h3> This study aimed to assess the clinical, biological, and radiological characteristics of osteomalacia and evaluate the diagnostic utility of the Adrar and Mac Kenna indices in confirming the diagnosis. <h3>Methods:</h3> We conducted a retrospective study of 45 patients hospitalized for osteomalacia between 2002 and 2022. We collected data on clinical symptoms (bone pain, muscle weakness, gait disturbances), biological parameters (serum calcium, phosphate, parathyroid hormone, 25-OH vitamin D, alkaline phosphatase, urinary calcium), and radiological findings (bone translucency, Looser-Milkmann lines, pathological fractures). We calculated the Adrar index (indicative of osteomalacia at scores ≥25) and the Mac Kenna index (indicative at scores ≥35) for all patients based on these parameters. We used chi-square tests for categorical variables and Pearson or Spearman correlations for continuous variables, with a significance level set at p<0.05. <h3>Results:</h3> The mean age of the patients was 46.4±16.79 years (range: 14–70), with a predominance of females (73%). Biologically, hypocalcemia was observed in 66.7% of patients, hypophosphatemia in 64.4%, and elevated alkaline phosphatase levels in 93.3%. Parathyroid hormone levels were elevated in 62.2% of patients, and 25-OH vitamin D deficiency was found in 84.5%. Radiologically, bone translucency was seen in 91% of patients, Looser-Milkmann lines in 40%, and bone deformities in 40%. Vitamin D deficiency was the most common etiology, accounting for 36% of cases. We identified significant correlations between clinical symptoms and biological parameters: bone pain correlated with urinary calcium (p=0.05), muscle weakness with serum calcium (p=0.04), and gait disturbances with phosphate (p=0.01), alkaline phosphatase (p=0.02), urinary calcium (p=0.01), and vitamin D levels (p=0.03). Fractures were significantly associated with low serum calcium (p=0.01), and bone deformities were strongly linked to low calcium levels (p=0.01). The Adrar and Mac Kenna indices showed high diagnostic reliability, with mean scores of 50.88±15.85 and 59.81±10.09, respectively. Both indices identified 97.8% of patients with scores consistent with osteomalacia. A strong concordance was observed between the two indices (p<10⁻³), confirming their utility as diagnostic tools independent of dietary calcium intake. <h3>Conclusion:</h3> This study emphasizes the importance of a comprehensive diagnostic approach to osteomalacia, incorporating clinical, biological, and radiological assessments. The Adrar and Mac Kenna indices proved to be reliable in confirming the diagnosis and facilitating early intervention. Targeted interventions based on these diagnostic tools could help prevent complications such as fractures and bone deformities. Further studies are needed to assess the long-term effectiveness of specific therapeutic strategies in managing osteomalacia. <h3>REFERENCES:</h3> <b>NIL</b>. <h3>Acknowledgements:</h3> <b>NIL</b>. <h3>Disclosure of Interests:</h3> <b>None declared</b>. © The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.