Background:Secondary causes of bone loss are sometimes overlooked in patients who are diagnosed as having osteoporosis. This is especially true if more than one risk factor for secondary osteoporosis is present, with clinicians focusing on the more common cause. Here we present a case of secondary osteoporosis caused by coeliac disease and multiple myeloma.Objectives:Secondary osteoporosis should be suspected in patients with very low bone mineral density and those with no obvious risk factors. Comprehensive examination and investigations must be done to look for all secondary causes because sometimes, as seen in our patient, you may find more than one.Methods:A 74 year old gentleman presented to the rheumatology clinic for assessment of osteoporosis. He had been recently diagnosed with coeliac disease. DXA scan showed a T score of -3.5 at the lumbar spine, -2.5 at the left hip and a low Z score of -2.9. He had not sustained any fractures in the past. There was no history of corticosteroid exposure and no parental history of hip fracture or osteoporosis. He drank up to 21 units of alcohol a week and was an ex-smoker. He was managing a gluten-free diet. His testosterone and vitamin D levels were normal. Serum electrophoresis, done as part of the osteoporosis workup, revealed a diagnosis of multiple myeloma. He then developed back pain and given his new diagnosis of myeloma, prompt investigations were carried out. A skeletal survey showed T7 fracture and a subsequent MRI scan showed impending cord compression, which were treated successfully with radiotherapy. He underwent chemotherapy and autologous stem cell transplantation for his myeloma.He recently had an OGD following one week post gluten rechallenge after an established gluten free diet. His biopsy shows no evidence of coeliac disease. Interestingly, the stem cell transplantation did not only treat our patient’s myeloma, but also his coeliac disease.Results:Z-score is a useful indicator of possible secondary osteoporosis. A score of −2.0 or less is below the expected range for age and should prompt careful scrutiny for an underlying cause.Coeliac disease is a gluten-sensitive enteropathy and a known cause for secondary osteoporosis. It likely causes bone loss by secondary hyperparathyroidism from vitamin D deficiency. Multiple myeloma is a disease of aging adults resulting in osteolytic and/or osteoporotic bone disease through increased bone resorption and decreased bone formation from pro-inflammatory cytokines. While coeliac disease patients are at increased risk of all malignancies, association with multiple myeloma is rare, but has been described.Conclusion:This case highlights the importance of evaluating for secondary causes for low bone mineral density and often, one may find more than one contributory factor. It also shows that a Z-score of −2.0 could help identify patients with a secondary cause for osteoporosis and those who would especially benefit from a thorough history and examination.