Endocrine Abstracts

A 57 year old Caucasian woman complained of severe back pain and arthralgia of large joints. Her arthralgia gradually got worse and she also noticed proximal muscle weakness. Blood tests showed normal CRP but elevated alkaline phosphatase of 521 iu/l with normal Gamma GT. Phosphate was low at 0.75 mmol/l with normal corrected calcium of 2.6 mmol/l. A DEXA scan suggested osteoporosis (Spine T −2.5). Isotope bone scan revealed increased activity in the right tibia and plain films confirmed multiple lytic lesions within her tibia as well as mid femur raising the suspicion of primary bone neoplasm or metastases.

CT scans of chest and abdomen as well as mammogram was normal. Bone biopsies showed intertrabecular fibrosis resorption and adjacent fibrosis in cores of thickened cortical bone. Renal function was normal but parathyroid hormone (PTH) was elevated at 1012 pg/ml and low vitamin D (25OHD 9.0 ng/ml). Anti endomysial antibodies were positive and small bowel biopsy confirmed coeliac disease. A diagnosis of osteomalacia due to gluten enteropathy and brown tumours due to secondary hyperparathyroidism was made. She was given dietary advice as well as Calcium & vitamin D supplements. Subsequently her parathyroid levels remained consistently elevated but now with persistently elevated serum calcium of 3.45 mmol/l. A large left lower parathyroid adenoma was then identified and resected. Post parathyroidectomy her calcium, phosphate, alkaline phosphatase and PTH are within normal limits. Repeat DEXA suggests improvement in osteoporosis (T score −0.3).

In this case the osteomalacia possibly masked the severe primary (or tertiary) hyperparathyroidism. Interpretation of total plasma-calcium is likely to be unreliable unless the 25-hydroxyvitamin-D levels can be shown or assumed to be normal.