Vitamin D is widely recognized as a hormone that is important for calcium homeostasis and maintenance of skeletal health. Vitamin D also plays a role in the function of the immune system (1-4). In vitro data have shown that 1,25-dihydroxyvitamin D (1,25[OH] 2 D) inhibits T cell proliferation and decreases the production of Th1 cytokines interleukin-2, interferon-␥, and tumor necrosis factor ␣ (5). Further, in vivo studies suggest that 1,25(OH) 2 D supplementation prevents the initiation and progression of inflammatory arthritis (collagen-induced arthritis) in rodents and prevents experimental autoimmune encephalomyelitis (a murine model used to determine the efficacy of drugs for the treatment of multiple sclerosis) (6,7).Additional evidence of an immunomodulating role of vitamin D in rheumatoid arthritis (RA) includes the localization of vitamin D receptors to macrophages, chondrocytes, and synoviocytes in tissues, such as rheu-

MRI scanning in patients with rheumatological conditions often shows bone marrow oedema, which can be secondary to inflammatory, degenerative, infective or malignant conditions but can also be primary. The latter condition is of uncertain aetiology and it is also uncertain whether it represents a stage in the progression to osteonecrosis in some patients. Patients with primary bone marrow oedema usually have lower limb pain, commonly the hip, knee, ankle or feet. The diagnosis is one of exclusion with the presence of typical MRI findings. Treatment is usually conservative and includes analgesics and staying off the affected limb. The natural history is that of gradual resolution of symptoms over a number of months. Evidence for medical treatment is limited, but open-label studies suggest bisphosphonates may help in the resolution of pain and improve radiological findings. Surgical decompression is usually used as a last resort.

The National Osteoporosis Society (NOS) published its document, Vitamin D and Bone Health: A Practical Clinical Guideline for Patient Management, in 2013 as a practical clinical guideline on the management of vitamin D deficiency in adult patients with, or at risk of developing, bone disease. There has been no clear consensus in the UK on vitamin D deficiency its assessment and treatment, and clinical practice is inconsistent. This guideline is aimed at clinicians, including doctors, nurses and dieticians. It recommends the measurement of serum 25 (OH) vitamin D (25OHD) to estimate vitamin D status in the following clinical scenarios: bone diseases that may be improved with vitamin D treatment; bone diseases, prior to specific treatment where correcting vitamin D deficiency is appropriate; musculoskeletal symptoms that could be attributed to vitamin D deficiency. The guideline also states that routine vitamin D testing is unnecessary where vitamin D supplementation with an oral antiresorptive treatment is already planned and sets the following serum 25OHD thresholds: <30 nmol/l is deficient; 30-50 nmol/l may be inadequate in some people; >50 nmol/l is sufficient for almost the whole population. For treatment, oral vitamin D3 is recommended with fixed loading doses of oral vitamin D3 followed by regular maintenance therapy when rapid correction of vitamin D deficiency is required, although loading doses are not necessary where correction of deficiency is less urgent or when co-prescribing with an oral antiresorptive agent. For monitoring, serum calcium (adjusted for albumin) should be checked 1 month after completing a loading regimen, or after starting vitamin D supplementation, in case primary hyperparathyroidism has been unmasked. However, routine monitoring of serum 25OHD is generally unnecessary but may be appropriate in patients with symptomatic vitamin D deficiency or malabsorption and where poor compliance with medication is suspected. The guideline focuses on bone health as, although there are numerous putative effects of vitamin D on immunity modulation, cancer prevention and the risks of cardiovascular disease and multiple sclerosis, there remains considerable debate about the evaluation of extraskeletal factors and optimal vitamin D status in these circumstances.

Osteoporosis is known to occur in patients with kidney transplants, but limited information is available about the prevalence and causes of this complication. We asked all 330 patients with kidney transplants in our unit to participate in this study of whom 165 (50%) agreed to do so. The characteristics of the participating patients were similar to the remaining 165 nonparticipants. Seventy of 165 (42%) of the participants were women of whom 40 were postmenopausal in contrast to the men of whom only one was hypogonadal. Bone mineral density (BMD) was significantly reduced at the radius (Z score, ؊1.5) and femoral neck (Z score, ؊0.7), but the lumbar spine was normal. BMD was lower in women than men at all skeletal sites. Osteoporosis was found in 10 -44% and osteopenia was found in 35-50% of women depending on the site. BMD was related inversely to time since transplantation and cumulative prednisolone dose. Twenty-seven of the 165 (16%) patients had either vertebral deformities or a history of a low trauma fracture after transplantation. This fracture group consisted of 10/27 (37%) men and 17/27 (63%) women, of whom 14 were postmenopausal. Fracture patients tended to be older and have a longer duration of renal failure, dialysis, transplantation, greater cumulative steroid dose, and higher bone resorption markers than the nonfracture group. No differences were found for cumulative doses of cyclosporin or tacrolimus. Logistic regression showed that only duration of dialysis and time since transplantation significantly increased fracture risk, with odds ratio (OR) for each year of dialysis or transplantation being 1.21 (CI, 1.00 -1.48) and 1.14 (CI, 1.05-1.23), respectively. These data show that low bone density and fractures are common in patients with kidney transplant and are determined by both pre-and posttransplant variables. Fracture risk was greatest in women, particularly if they were postmenopausal and we recommend that this subgroup is targeted for assessment and treatment.