Effects of competitive physical activity on serum irisin levels and bone turnover markers

Background Irisin, a myokine, is a polypeptide derived from the cleavage of the extracellular domain of fibronectin domain-containing protein 5, a receptor that is present on different tissues (skeletal muscle, pericardium, myocardium, and brain), whose functions are not yet fully defined. Purpose The main aim of our study was to evaluate the effect of competitive physical activity on serum irisin levels and bone turnover markers. Methods Fifteen male footballers and an equal number of subjects of the same age and gender, but with a predominantly sedentary lifestyle, had their serum levels of irisin and bone turnover markers measured. Bone mineral status was evaluated in both groups by quantitative bone ultrasound of the calcaneus. In addition, only in footballers, biochemical analyses were repeated after 3 months. Results We did not observe significant differences in the serum levels of calcium, phosphorus, and parathyroid hormone between the two groups. The footballers had significantly higher quantitative bone ultrasound, 25-OH vitamin D, and creatinine values than the controls. There were also no significant differences in the bone alkaline phosphatase, carboxy-terminal telopeptide of type I collagen, osteoprotegerin, sclerostin or Dkk-1 values, while the irisin levels (+ 89%, p < 0.001) and RANKL were significantly higher in the footballers compared to those in the controls. Conclusion Our study shows that footballers have significantly higher serum irisin values than the general population. Irisin could be the "trait d’union" between bone health and physical activity.

Osteolipoma in the Forearm

A case of left distal forearm and wrist osteolipoma in a 56 year old female is reported. The patient presented with a 3 year history of nontender left wrist mass. Radiographs demonstrated a lobulated mass of mixed low density and calcifications, not adjacent to and with no connection to underlying bone. Ultrasound showed a spheroid hyperechoic lesion with internal heterogeneity and rim of calcifications. Magnetic resonance imaging revealed a lesion with predominantly fat characteristics on T1 weighted and T2 weighted sequences, with rim of peripheral calcification and specks of internal calcification. Histological examination after excision of the mass showed the lesion to be an osteolipoma. Osteolipoma is a rare variant of lipoma with osseous metaplasia and should be considered in the differential of a fat containing mass with ossification.