[Bone and metabolism]

Bone is now considered as a particular endocrine organ. Its endocrine function is not yet fully understood and has been the subject of several conferences at the European Society of Endocrinology Congress 2018. Bone regulates phosphate metabolism by secreting fibroblast growth factor 23; it also regulates glucose metabolism via osteocalcin and energy metabolism, thanks to lipocalin 2, a new hormone acting on the brain. In addition, the incidence of diabetes continues to grow, and its impact on bone has been demonstrated, with an increased risk of fractures regardless the type of diabetes. The mechanism of bone fragility in this disease is not fully known but it involves a decrease in bone turnover and bone demineralization. Recent findings on the role of bone on glucose and mineral metabolism could open therapeutic perspectives, especially for the treatment of diabetes or obesity.

[Update 2017 of the KDIGO guidelines on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). What are the real changes?]

Guidelines for the assessment, diagnosis and therapy of the alterations that characterize the CKD-MBD are an important support in the clinical practice of the nephrologist. Compared to the KDIGO guidelines published in 2009, the 2017 update made changes on some topics on which there was previously no strong evidence both in terms of diagnosis and therapy. The recommendations include the diagnosis of bone anomalies in CKD-MBD and the treatment of mineral metabolism abnormalities with particular regard to hyperphosphataemia, calcium levels, secondary hyperparathyroidism and anti-resorptive therapies. The Italian Study Group on Mineral Metabolism, in reviewing the 2017 recommendations, aimed to assess the weight of the evidence that led to this update. In fact, on some topics there has not been a substantial difference on the degree of evidence compared to the previous guidelines. The Italian Study Group emphasizes the points that may still reserve critical issues, including interpretation, and invites an evaluation that is articulated and personalized for each patient.

Asfotase alfa treatment for 1 year in a 16 year-old male with severe childhood hypophosphatasia

We describe the clinical outcome of asfotase alfa therapy in a 16-year-old boy with severe childhood hypophosphatasia (HPP), who began therapy at age 15 years. The patient was diagnosed with HPP at age 2 years when he presented with genu varum and premature loss of primary teeth. He had a history of multiple fractures requiring 16 orthopedic surgeries with rod and pin placement in his lower extremities. He had chronic skeletal pain and used cane to ambulate with great difficulty. His height Z score at age 15 years was - 5. He had severe scoliosis and deformity of both legs. Bone radiograph showed hypomineralization and characteristic "tongues" of radiolucency in the distal radius and ulna. His serum alkaline phosphatase level was stable, with elevated serum pyridoxal 5'-phosphate and urine phosphoethanolamine, consistent with HPP. He was started on asfotase alfa 2 mg/kg given subcutaneously thrice weekly. He had marked clinical improvement in mobility with no report of pain after 3 months of treatment. At 6 month, he walked without cane and participated in outdoor activities with peers. Bone radiograph at 6 months showed striking improvement in previous radiolucent areas. At 9 months, his annualized growth velocity was 9.5 cm/year, while growth velocity of arm span was 12 cm/year. However, at 12 months, he was noted to have worsening scoliosis from 60 degrees before therapy to 110 degrees, with a slight decrease in height, necessitating a spinal fusion surgery. In conclusion, treatment with asfotase alfa significantly improved physical function, pain, overall quality of life, and skeletal radiographic findings in this patient. Close monitoring for progression of scoliosis in adolescents with HPP treated with asfotase alfa is recommended.

TDF and quantitative ultrasound bone quality in African patients on second line ART, ANRS 12169 2LADY sub-study

BACKGROUND

Bone demineralization, which leads to osteoporosis and increased fracture risk, is a common metabolic disorder in HIV-infected individuals. In this study, we aimed to assess the change in bone quality using quantitative ultrasound (QUS) over 96 weeks of follow-up after initiation of second-line treatment, and to identify factors associated with change in bone quality.

METHODS AND FINDINGS

In a randomized trial (ANRS 12169), TDF and PI-naïve participants failing standard first-line treatment, from Burkina Faso, Cameroon, and Senegal were randomized to receive either TDF/FTC/LPVr, ABC/ddI/LPVr or TDF/FTC/DRVr. Their bone quality was assessed using calcaneal QUS at baseline and every 24 weeks until week 96. Stiffness index (SI) was used to measure bone quality. Out of 228 participants, 168 (74%) were women. At baseline, median age was 37 years (IQR: 33-46 years) and median T-CD4 count was 199 cells/μl (IQR: 113-319 cells/μl). The median duration of first-line antiretroviral treatment (ART) was 52 months (IQR: 36-72 months) and the median baseline SI was 101 (IQR: 87-116). In multivariable analysis, factors associated with baseline SI were sex (β = -10.8 [-18.1,-3.5] for women), age (β = -8.7 [-12.4,-5.1] per 10 years), body mass index (BMI) (β = +0.8 [0.1,1.5] per unit of BMI), and study site (β = +12.8 [6.5,19.1] for Cameroon). After 96 weeks of second-line therapy, a reduction of 7.1% in mean SI was observed, as compared with baseline. Factors associated with SI during the follow-up were similar to those found at baseline. Exposure to TDF was not associated with a greater loss of bone quality over time.

CONCLUSION

Bone quality decreased after second-line ART initiation in African patients independently of TDF exposure. Factors associated with bone quality include age, sex, baseline BMI, study site, and duration of follow-up.

Osteoporosis: A Future Public Health Problem for Israel? Medical and Legal Obligations

Starvation in early life can lead to premature metabolic syndrome and bone demineralization. Osteoporosis in the Jewish population may not yet be a recognized syndrome, but the harsh conditions to which Holocaust survivors were exposed may have increased the incidence of the condition. Immigrants and refugees who came to Israel from East Africa and Yemen - whether decades ago or more recently - may have been at increased risk of under-nutrition during pregnancy, affecting both the mother and consequently the offspring. This malnutrition may be further exacerbated by rapid overfeeding in the adopted developed country. This problem was also recognized at the turn of the 21st century in poor and underdeveloped countries and is becoming a global public health issue. In this review, the risks for premature metabolic syndrome and bone demineralization are enumerated and preventive measures outlined.

AAV8-mediated expression of N-acetylglucosamine-1-phosphate transferase attenuates bone loss in a mouse model of mucolipidosis II

Mucolipidoses II and III (ML II and ML III) are lysosomal disorders in which the mannose 6-phosphate recognition marker is absent from lysosomal hydrolases and other glycoproteins due to mutations in GNPTAB, which encodes two of three subunits of the heterohexameric enzyme, N-acetylglucosamine-1-phosphotransferase. Both disorders are caused by the same gene, but ML II represents the more severe phenotype. Bone manifestations of ML II include hip dysplasia, scoliosis, rickets and osteogenesis imperfecta. In this study, we sought to determine whether a recombinant adeno-associated viral vector (AAV2/8-GNPTAB) could confer high and prolonged gene expression of GNPTAB and thereby influence the pathology in the cartilage and bone tissue of a GNPTAB knock out (KO) mouse model. The results demonstrated significant increases in bone mineral density and content in AAV2/8-GNPTAB-treated as compared to non-treated KO mice. We also showed that IL-6 (interleukin-6) expression in articular cartilage was reduced in AAV2/8-GNPTAB treated ML II mice. Together, these data suggest that AAV-mediated expression of GNPTAB in ML II mice can attenuate bone loss via inhibition of IL-6 production. This study emphasizes the value of the MLII KO mouse to recapitulate the clinical manifestations of the disease and highlights its amenability to therapy.

Bone demineralisation in a large cohort of Wilson disease patients

AIMS AND BACKGROUND

We compared the bone mineral density (BMD) of adult Wilson disease (WD) patients (n = 148), with an age- and gender-matched healthy control population (n = 148). Within the WD cohort, correlations of BMD with WD disease parameters, lab results, type of treatment and known osteoporosis risk factors were analysed.

METHODS

Hip and lumbar spine absolute BMD and T-score were measured by dual-energy X-ray absorptiometry. Osteoporosis and osteopenia were defined as a T-score ≤ -2.5, and between -1 and -2.5, respectively.

RESULTS

There were significantly more subjects with abnormal T-scores in the WD population (58.8%) than in the control population (45.3%) (χ(2) = 6.65, df = 2, p = 0.036), as there were 50.0% osteopenic and 8.8% osteoporotic WD patients, vs. 41.2% and 4.1%, respectively, in the controls. Especially L2-L4 spine BMD measurements (BMD and T-scores) differed significantly between the WD population and matched controls. L2-L4 spine BMD for WD patients was on average 0.054 g/cm(2) (5.1%) lower than in matched normal controls (0.995 ± 0.156 vs 1.050 ± 0.135; p = 0.002). We found no significant correlation between BMD values and any of the WD disease parameters (e.g. the severity of liver disease), lab results, type of treatment or known osteoporosis risk factors. Duration of D-penicillamine treatment was negatively correlated with femoral BMD value, but in a clinically irrelevant manner, compared to age and gender. Importantly, BMD remained significantly lower in WD patients (n = 89) vs. controls after excluding WD patients with cirrhosis (p = 0.009).

CONCLUSIONS

Our study suggests that WD is intrinsically associated with bone demineralisation.

Pulsed focused ultrasound treatment of muscle mitigates paralysis-induced bone loss in the adjacent bone: a study in a mouse model

Bone loss can result from bed rest, space flight, spinal cord injury or age-related hormonal changes. Current bone loss mitigation techniques include pharmaceutical interventions, exercise, pulsed ultrasound targeted to bone and whole body vibration. In this study, we attempted to mitigate paralysis-induced bone loss by applying focused ultrasound to the midbelly of a paralyzed muscle. We employed a mouse model of disuse that uses onabotulinumtoxinA-induced paralysis, which causes rapid bone loss in 5 d. A focused 2 MHz transducer applied pulsed exposures with pulse repetition frequency mimicking that of motor neuron firing during walking (80 Hz), standing (20 Hz), or the standard pulsed ultrasound frequency used in fracture healing (1 kHz). Exposures were applied daily to calf muscle for 4 consecutive d. Trabecular bone changes were characterized using micro-computed tomography. Our results indicated that application of certain focused pulsed ultrasound parameters was able to mitigate some of the paralysis-induced bone loss.

Cortical bone mechanical properties are altered in an animal model of progressive chronic kidney disease

Chronic kidney disease (CKD), which leads tocortical bone loss and increasedporosity,increases therisk of fracture. Animal models have confirmed that these changes compromise whole bone mechanical properties. Estimates from whole bone testing suggest that material properties are negatively affected, though tissue-level assessmentshavenot been conducted. Therefore, the goal of the present study was to examine changes in cortical bone at different length scales using a rat model with theprogressive development of CKD. At 30 weeks of age (∼75% reduction in kidney function), skeletally mature male Cy/+ rats were compared to their normal littermates. Cortical bone material propertieswere assessed with reference point indentation (RPI), atomic force microscopy (AFM), Raman spectroscopy,and high performance liquid chromatography (HPLC). Bones from animals with CKD had higher (+18%) indentation distance increase and first cycle energy dissipation (+8%) as measured by RPI.AFM indentation revealed a broader distribution of elastic modulus values in CKD animals witha greater proportion of both higher and lower modulus values compared to normal controls. Yet, tissue composition, collagen morphology, and collagen cross-linking fail to account for these differences. Though the specific skeletal tissue alterations responsible for these mechanical differences remain unclear, these results indicate that cortical bone material properties are altered in these animals and may contribute to the increased fracture risk associated with CKD.

A study to evaluate the cause of bone demineralization in gynecological cancer survivors

BACKGROUND

An association between treatment for gynecological cancers and risk of osteoporosis has never been formally evaluated. Women treated for these cancers are now living longer than ever before, and prevention of treatment-induced morbidities is important. We aimed to distinguish, in gynecological cancer survivors, whether cancer therapy has additional detrimental effects on bone health above those attributable to hormone withdrawal.

METHODS

We performed a retrospective cross-sectional analysis of dual energy x-ray absorptiometry (DEXA) scan results from 105 women; 64 had undergone bilateral salpingo-oophorectomy (BSO) followed by chemotherapy or radiotherapy for gynecological malignancies, and 41 age-matched women had undergone BSO for benign etiologies. All were premenopausal prior to surgery.

RESULTS

The median age at DEXA scan for the cancer group was 42 years, and 66% had received hormonal replacement therapy (HRT) following their cancer treatment. For the benign group, the median age was 40 years, and 87% had received HRT. Thirty-nine percent of cancer survivors had abnormal DEXA scan results compared to 15% of the control group, with the majority demonstrating osteopenia. The mean lumbar spine and femoral neck bone mineral densities (BMDs) were significantly lower in cancer patients. A history of gynecological cancer treatment was associated with significantly lower BMD in a multivariate logistic regression.

CONCLUSIONS

Women treated for gynecological malignancies with surgery and adjuvant chemotherapy have significantly lower BMDs than age-matched women who have undergone oophorectomy for noncancer indications. Prospective evaluation of BMD in gynecological cancer patients is recommended to facilitate interventions that will reduce the risk of subsequent fragility fractures.

[Mid-term effectiveness of total hip arthroplasty with collum femoris preserving prosthesis]

OBJECTIVE

To discuss the clinical application of total hip arthroplasty (THA) with collum femoris preserving (CFP) prosthesis and to analyze the mid-term effectiveness.

METHODS

Between January 2004 and February 2007, 45 patients (48 hips) underwent THA with CFP prosthesis. There were 29 males (31 hips) and 16 females (17 hips) with an average age of 48.8 years (range, 38-60 years), including 20 left hips, 22 right hips, and 3 bilateral hips. The causes of hip replacement were osteoarthritis (20 cases), avascular necrosis of femoral head (13 cases), dysplasia (4 cases), rheumatoid arthritis (3 cases), posttraumatic osteoarthritis (2 cases), ankylosing spondylitis (2 cases), and Perths disease (1 case). The average disease duration was 6.1 years (range, 2-13 years). Harris scores, visual analogue scale (VAS) score, and the hip range of motion (ROM) were recorded at pre- and post-operation. The X-ray films were taken at pre- and post-operation to observe the position, loosening of the prosthesis, and ectopic ossification. The gait of patients were also evaluated during follow-up. Short-form 36 health survey scale (SF-36) was used to evaluate the life quality of patients.

RESULTS

All 45 patients were followed up 5-8 years with an average of 6.4 years. All the incisions healed by first intention. No infection, hip dislocation, nerve injury, or deep vein thrombosis occurred. Six cleavage fractures (13.3%) of the lateral femoral diaphysis at the distal prosthesis occurred during operation, which healed at 8 months postoperatively without any treatment. Mild ectopic ossification occurred in 4 patients (8.9%) who had no discomfort. Five patients (11.1%) had bone mineral density loss in the region of the proximal femur. The survival rates of the cups and stems were all 100% at last follow-up. The results of Harris score, VAS score, and ROM of the hip joint at 1 year postoperatively and last follow-up were significantly better than preoperative ones (P < 0.05). No significant difference was found in VAS score and ROM of the hip joint between at 1 year postoperatively and at last follow-up (P > 0.05) except the Harris score (P < 0.05). According to Harris functional assessment at last follow-up, the results were excellent in 31 hips, good in 11 hips, and fair in 6 hips with an excellent and good rate of 87.5%. The physiological role, body pain, and total health scores were significantly lower than the reference value of urban men from Sichuan province (P < 0.05), but no significant difference was found in the other scores of the SF-36 when compared with the reference value (P > 0.05).

CONCLUSION

THA with CFP prosthesis is a good option for the young patient with complete collum femoris and without osteoporosis, and can achieve good mid-term effectiveness.

Vitamin D, parathyroid hormone, and bone mineral density status in kidney transplant recipients

INTRODUCTION

Bone disease and bone fractures are common among kidney transplant recipients. The aim of this study was to investigate the prevalence of vitamin D deficiency, hyperparathyroidism, and osteoporosis kidney transplant patients.

MATERIALS AND METHODS

A total of 113 kidney transplant recipients (58 women and 55 men) were selected consecutively from the transplant clinic between January and April 2010. A serum sample from each patient was analyzed for creatinine, calcium, phosphorus, 25-hydroxyvitamin D, and intact parathyroid hormone levels. Bone mineral density was measured by the dual energy x-ray absorptiometry method and classified according to the classification of the World Health Organization. Risk factors of bone mineral density outcomes were evaluated in univariable and multivariable analyses.

RESULTS

Forty-five percent of the patients had vitamin D deficiency and 76.2% had hyperparathyroidism. There was a significant correlation between vitamin D deficiency and high serum parathyroid hormone (P = .04) and serum creatinine levels (P = .001). However, there were no significant associations of serum calcium and phosphorus with vitamin D or parathyroid hormone levels. The osteoporosis and osteopenia were reported in 12.4% and 52.2% of the recipients in the lumbar spine and 45.1% and 36.3% of the patients in the femoral neck, respectively. Multivariable analyses showed that there were significant correlations between patients' age and body mass index and femoral neck osteoporosis. Risk factors for lumbar spine osteoporosis were end-stage renal disease duration, serum calcium, and body mass index.

CONCLUSIONS

Vitamin D deficiency, hyperparathyroidism, and osteoporosis are very common in our kidney transplant recipients. Early diagnosis and treatment of these abnormalities should be included in the posttransplant follow-up of patients in order to prevent severe bone diseases and bone fractures.

Bone density and cortical structure after pediatric renal transplantation

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area. At baseline, compared with reference participants, renal transplant recipients had significantly lower mean section modulus and muscle area; trabecular BMD was significantly greater than reference participants only in transplant recipients younger than 13 years. After transplantation, trabecular BMD decreased significantly in association with greater glucocorticoid exposure. Cortical BMD increased significantly in association with greater glucocorticoid exposure and greater decreases in parathyroid hormone levels. Muscle and fat area both increased significantly, but section modulus did not improve. At 12 months, transplantation associated with significantly lower section modulus and greater fat area compared with reference participants. Muscle area and cortical BMD did not differ significantly between transplant recipients and reference participants. Trabecular BMD was no longer significantly elevated in younger recipients and was low in older recipients. Pediatric renal transplant associated with persistent deficits in section modulus, despite recovery of muscle, and low trabecular BMD in older recipients. Future studies should determine the implications of these data on fracture risk and identify strategies to improve bone density and structure.

[Hepatic osteodystrophy in patients with liver cirrhosis]

The article presents research data of BMD in 106 patients with liver cirrhosis. The core group of examined patients presented with LC patients the etiology of alcohol--37.7% and primary biliary cirrhosis--35.8%. In 68.9% of patients with established deficits of bone mineral density, by 24.6%--at the level of osteoporosis. Was detected influence of the etiology of the disease on the frequency of osteopenia and osteoporosis containment. Was made analysis of dependence of the frequency of osteopenia, and/or osteoporosis of population risk factors, duration of disease, grade of liver failure on the Child-Pugh. A comparative assessment of the effectiveness treatment of disorders of BMD active metabolite of vitamin D3--alpha caltsidol and drugs from the group of bisphosphonates.

Low bone density is not always bisphosphonate deficiency

Low bone density is not a one-size-fits-all disorder. We need to carefully consider the diagnostic and therapeutic options before assuming that low bone density is osteoporosis.

Severe bone demineralisation is associated with higher mortality in children with cystic fibrosis

Decreased bone mineral density (BMD) is an emerging problem for clinicians who care for children with Cystic fibrosis (CF). The aim of this study was to determine prevalence and assess risk factors for reduced BMD in our adolescent population with CF. All bone densitometry scans (n=99) performed on children (n=79) with a mean age 13.6 (10-19.2) years over a 7 year period (2000-2007) were reviewed. Patient records were reviewed for correlating clinical data. Low BMD is frequently present in adults and children with variable reports (36-66%). In our study, BMD expressed as z score of L2-L4 spine was reduced in a total of 50% children with a preponderance of males. Bone demineralization was strongly associated with increasing age (p=0.03), diminished lung function (p=0.027), reduced body mass index (p=0.001) and treatment with oral corticosteroids (p=0.02).

Bone demineralization in adult thalassaemic patients: contribution of GH and IGF-I at different skeletal sites

BACKGROUND AND OBJECTIVE

GH and IGF-I exert an important role in the control of bone formation, as shown by decreased bone mineral density and increased fracture risk in adult hypopituitary patients untreated for GH deficiency (GHD). Different degrees of bone demineralization are frequently reported in patients affected by beta-thalassaemia. Considering the high prevalence of GHD recently observed by our group among adult thalassaemic patients, we elected to study the possible role of GH-IGF-I abnormalities in the pathogenesis of the osteopenia/osteoporosis of this disease.

DESIGN

Sixty-four adult thalassaemic patients (49 with thalassaemia major and 15 with thalassaemia intermedia, 23 men and 41 women, aged 31.4 +/- 6.8 years) were studied.

METHODS

Bone mineral density was assessed by dual energy X-ray absorptiometry at lumbar spine in 62 patients and at proximal femur in 58. All patients underwent GHRH (1 microg/kg as an i.v. bolus) plus arginine (0.5 g/kg as a 30-min i.v. infusion) testing. Severe GHD was defined by GH peaks < 9 microg/l, whereas partial GHD was defined by GH peaks ranging from 9 to 16.5 microg/l. Blood samples for IGF-I measurement were collected.

RESULTS

Lumbar osteoporosis and osteopenia were demonstrated in 46/62 (74.1%) and 14/62 (22.5%) patients, respectively. Femoral osteoporosis and osteopenia were documented in 22/58 (37.9%) and 32/58 (55.1%) patients, respectively. Severe GHD was demonstrated in 16/64 patients (25%), while 11 additional patients (17.1%) displayed partial GHD. IGF-I standard deviation score (SDS) was low, that is, below -1.88, in the majority (54.6%) of patients. Lumbar T-score values were not correlated with either GH peaks or IGF-I SDS values. Femoral T-score values were positively correlated with GH peaks (r = 0.38, P < 0.005) and IGF-I SDS values (r = 0.39, P < 0.005). Multiple regression analysis pointed to both GH peak and IGF-I SDS as predictors of femoral T-score. Furthermore, mean femoral T-score was significantly lower in patients with severe GHD than in those with normal GH secretion (-2.94 +/- 0.25 vs.-2.15 +/- 0.12, P < 0.01).

CONCLUSION

This study, while confirming the high prevalence of both osteopenia/osteoporosis and somatotropin-somatomedin deficiency in adult thalassaemic patients, indicates that defective GH secretion and diminished serum IGF-I levels may contribute to femoral demineralization in these patients. Further studies are worth carrying out to evaluate the efficacy of biosynthetic GH administration on bone abnormalities of GH-deficient thalassaemic adults.

[Fractures and chronic renal insufficiency]

Chronic renal insufficiency (CRI) causes important modifications in the metabolism of phosphorus and calcium, to which frequently resulting in serious disorders of the skeleton, including demineralization, reduction of the bone resistance and a higher risk of fractures. Renal osteodystrophy is the term used to describe these disorders; they are generally heterogeneous and are classified according to the state of bone turnover into secondary hyperparathyroidism, adynamic bone, and osteomalacia. The incidence of hip fractures in the patients with CRI is higher than in the general population. Hip fractures are an important cause of morbidity and mortality. The evaluation of the fracture risk in the patients with different degrees of CRI is problematic, in particular because of the difficulty in identifying fractures, especially vertebral ones. The instrumental index that best expresses the fracture risk in the general population is bone mineral density (BMD); however, the relationship between low BMD and CRI is disputed. Bone disorders in patients with CRI have in fact a multifactorial pathogenesis and low BMD is not the only risk factor for fractures. Besides densitometric evaluation, also that vertebral morphometric evaluation would be desirable in patients with CRI. The fracture risk increases progressively with the severity of chronic renal disease and it is especially high in patients with renal insufficiency in more advanced-stages CRI (creatinine clearance<15-20 mL/min). However, not only in patients with severe CRI undergoing dialysis, but also in those with milder renal disease is the risk of bone fractures high.

[Anorexia nervosa and its consequences on bone: a therapeutic challenge]

It has been estimated that osteoporosis is present in 20 to 50% of women with anorexia nervosa, with an increased fracture risk particularly at non vertebral sites. Thus, bone loss is a major clinical concern in anorexia nervosa patients, justifying systematic evaluation. However, evidence-based therapeutic options are limited.

Assessment of bone and mineral metabolism in inflammatory bowel disease: case series and review

OBJECTIVE

To determine the prevalence of low bone mass, fractures, and vitamin D deficiency and the levels of biochemical markers of mineral metabolism in patients with inflammatory bowel disease (IBD).

METHODS

Our retrospective study consisted of 30 patients with Crohn's disease (CD) and 18 patients with ulcerative colitis (UC). Dual-energy x-ray absorptiometry was performed to determine bone mineral density at the lumbar spine and hip. Serum calcium, phosphorus, parathyroid hormone, 25-hydroxyvitamin D (25-OHD), and 1,25-dihydroxyvitamin D, urinary N-telopeptide cross-linked collagen type I, and 24-hour urinary calcium levels were evaluated.

RESULTS

On the basis of Z-score definitions of low bone mass in the IBD group as a whole, 13 patients (27%) had low bone mass at the lumbar spine. Similarly, at the femoral neck, 13 patients (27%) had low bone mass. There was a higher prevalence of low bone mass in the UC group than in the CD group, consistent with a high prevalence of fractures in that group. Of all patients with IBD, 65% had a history of fractures, of which 23% were atraumatic. Deficiency of 25-OHD was high, with a prevalence of 55% in patients with UC and 83% in patients with CD. Secondary hyperparathyroidism, defined as a parathyroid hormone level >55 pg/mL in conjunction with a low or normal serum calcium and a low 25-OHD level, was present in 50% of patients with CD and only 7% of patients with UC.

CONCLUSION

Metabolic bone disease and fractures are common in IBD. The mean bone mineral density of the spine or femoral neck did not differ significantly between patients with CD and those with UC. Patients with UC had a higher prevalence of low bone mass, as defined by a Z-score of less than -2, than did patients with CD, consistent with a high prevalence of fractures in the UC group. In contrast, hyperparathyroidism attributable to vitamin D deficiency was more prevalent in patients with CD than in those with UC. This finding suggests a different etiologic mechanism of low bone mass in patients with CD.