Endocrine Abstracts

Background: Hypophosphatemic osteomalacia (HPO)is an uncommon metabolic disease. We describe a case of HPO, where radiological findings of the looser zone (pseudo fractures) were confused with an actual fracture and were scheduled for orthopaedic intervention. Extensive biochemical and radiological investigations followed by an endocrinology review enabled the diagnosis of HPO and prevented surgical intervention.

Case history: A 60-year-old gentleman presented to primary care with extensive bony pains and resultant poor mobility. Endocrine, rheumatology, and orthopaedics teams extensively investigated him. He was found to have multiple fractures in various, and a DEXA scan reported osteoporosis of the hips. An initial pelvis X-ray was reported as bilateral neck of femur fractures (NOF), although clinically, he did not have NOF. Therefore, the Orthopaedic team requested a CT scan of the hip for further clarity before surgery. The CT was reported as Subacute left femoral neck and right femoral shaft. Fracture appearances are in keeping with atypical femoral fractures, and metabolic/pathological causes should be explored, particularly bisphosphonate-related femoral fractures. The patient was re-admitted for elective surgery, for which he drove to the ED and mobilised to the ward. Further endocrine input and biochemical evaluations were requested to review the metabolic aspect, as his calcium and phosphate levels were low. Reviewing all previous investigations, an endocrine team concluded that this is a case of hypophosphatemia osteomalacia (HPO) and resultant pseudo fracture (Loosers zones). Investigations Ad. Calcium 2.11, PTH 13, Vitamin D 108 Renal and Thyroid function Normal ALP 440, Phosphate (0.35-0.7), Bone turnover markers-P1 NP 88 and CTX (raised), 24 Hour Urine Calcium – Normal Magnesium 0.91, Albumin 42 Protein electrophoresis, PSA and CK normal. Coeliac screen negative MRI left lower leg-Linear non-continuous fracture of the Tibia. MRI spine -Disc bulge CT-TAP-Healing Rib fracture Bone scan-extensive and symmetrical uptake (Not typical of Paget’s disease) Treatment Treated with sando Phosphate, active Vitamin D3(calcitriol), and oral calcium. Conclusions Treatment with phosphate and calcium supplements improved his bony pain and mobility. Further radiological evidence of bone healing was noted. Diagnosing HPO remains challenging to Endocrinologists and physicians due to its low prevalence and nonspecific manifestations. Blood tests for electrolytes, particularly serum phosphate and bone mineral density (BMD), are a primary clue for diagnosis. Fracture lines in osteomalacia are very common and can be confused with actual fractures. They may consist of pseudo fractures (Characteristic of HO), actual fractures, or insufficiency fractures.