Osteomalacia revisited : a report on 28 cases

Area of Science:

• Endocrinology
• Bone Metabolism
• Clinical Medicine

Background:

• Osteomalacia (OM) is a bone disorder characterized by impaired mineralization.
• Understanding the diverse causes and clinical presentations of OM is crucial for effective management.
• Previous studies have highlighted various etiologies, but comparative analyses of distinct OM subtypes are less common.

Purpose of the Study:

• To analyze the clinical manifestations and frequent causes of osteomalacia in a cohort of 28 patients over a 20-year period.
• To differentiate between vitamin D deficiency osteomalacia (VD-OM) and hypophosphatemic osteomalacia (HypoP-OM) based on clinical and biochemical parameters.
• To identify discriminatory laboratory findings for each type of osteomalacia.

Main Methods:

• Retrospective analysis of 28 patients diagnosed with osteomalacia.
• Diagnosis confirmed by bone biopsy and/or Bingham and Fitzpatrick criteria.
• Classification into VD-OM, HypoP-OM, and OM-associated hypophosphatasia based on etiology.
• Clinical symptoms, bone mineral density, and biochemical markers (serum calcium, phosphate, total alkaline phosphatase, vitamin D, PTH, FGF23, calciuria, phosphaturia) were assessed.

Main Results:

• The study identified similar frequencies of VD-OM (13 patients) and HypoP-OM (14 patients).
• Common causes included deficient sun exposure and celiac disease for VD-OM, and hereditary forms for HypoP-OM.
• Clinical manifestations frequently included polyarthralgias (89%) and fractures (75%).
• VD-OM patients exhibited higher total AP and PTH, but lower vitamin D, calcium, and bone mass compared to HypoP-OM patients.
• HypoP-OM patients showed lower serum phosphate and higher phosphaturia.
• Urinary calcium < 50 mg/dl and serum phosphate < 2.3 mg/dl were highly discriminatory for VD-OM and HypoP-OM, respectively.

Conclusions:

• Hypophosphatemic OM and vitamin D deficiency OM occurred with similar frequencies in this cohort.
• Elevated total alkaline phosphatase and decreased serum phosphate were the most common laboratory abnormalities.
• Distinct urinary calcium and serum phosphate levels can help differentiate between VD-OM and HypoP-OM.
• Osteomalacia patients frequently present with low bone density and fractures, necessitating thorough diagnostic evaluation.