Clinical, biochemical, and radiological features of osteomalacia: evaluation of diagnostic approaches in a retrospective study of 33 cases
Osteomalacia is a generalized bone disorder characterized by defective bone mineralization. Definitive etiological diagnoses of osteomalacia remain challenging and are not fully standardized. We aim to describe clinical, biochemical, and radiographic features, elucidate the utility of various diagnosis methods, and propose a diagnostic strategy. A retrospective study involving 33 patients with osteomalacia over a 15-year period at our Rheumatology Department. The mean age was 50.6 years (range: 17-87 years), with a female predominance (sex-ratio=0.18). Clinical signs included bone pain (87.8%), gait disturbance (63.6%), motor deficit (54.5%), clinically apparent bone deformity (21.2%), fragility fracture (24.2%), and muscle pain (42.2%). Radiologically, diffuse bone demineralization was observed in 91% of patients. Other signs included Looser Milkman streaks (60.6%), bone deformities (39.5%), and bone fractures (55%). Low bone mineral density was observed in 85% of tested patients while 60% of them had densitometric osteoporosis. Main biochemical disorders included increased alkaline phosphatase levels (85%), hypocalcemia (88%), and hypophosphatemia (61%). Parathyroid hormone levels were elevated in 82% of cases, 25-hydroxyvitamin D level was reduced in all cases. All patients in our study fulfilled both the McKenna and the Adrar indexes for osteomalacia diagnosis. Both diagnostic indexes were significantly and positively correlated (r=0.56, p=0.01). Vitamin D-related osteomalacia was the predominant etiology, with vitamin D malabsorption observed in nine patients, seven of whom had celiac disease. Chronic kidney failure was observed in five cases. Osteomalacia was associated with renal phosphate leak in four cases. The presentation and etiologies of osteomalacia are diverse. Diagnosis relies on clinical, biochemical, and radiological findings and can be aided by diagnostic indexes such as McKenna's and Adrar's. Bone biopsy should be reserved for cases where the diagnosis is doubtful.