Hepatic osteodystrophy in chronic cholestasis: evidence for a multifactorial etiology

Osteosarcopenia in autoimmune cholestatic liver diseases: Causes, management, and challenges

Primary biliary cholangitis and primary sclerosing cholangitis (PSC) are the most common cholestatic liver diseases (CLD) in adults and are both characterized by an immune pathogenesis. While primary biliary cholangitis is a model autoimmune disease, with over 90% of patients presenting very specific autoantibodies against mitochondrial antigens, PSC is considered an immune mediated disease. Osteoporosis is the most common bone disease in CLD, resulting in frequent fractures and leading to significant morbidity. Further, sarcopenia is emerging as a frequent complication of chronic liver diseases with a significant prognostic impact and severe implications on the quality of life of patients. The mechanisms underlying osteoporosis and sarcopenia in CLD are still largely unknown and the association between these clinical conditions remains to be dissected. Although timely diagnosis, prevention, and management of osteosarcopenia are crucial to limit the consequences, there are no specific guidelines for management of osteoporosis and sarcopenia in patients with CLD. International guidelines recommend screening for bone disease at the time of diagnosis of CLD. However, the optimal monitoring strategies and treatments have not been defined yet and vary among centers. We herein aim to comprehensively outline the pathogenic mechanisms and clinical implications of osteosarcopenia in CLD, and to summarize expert recommendations for appropriate diagnostic and therapeutic approaches.

Multidisciplinary Management of Alagille Syndrome

Alagille syndrome (ALGS) is an autosomal dominant disorder characterized by involvement of various organ systems. It predominantly affects the liver, skeleton, heart, kidneys, eyes and major blood vessels. With myriads of presentations across different age groups, ALGS is usually suspected in infants presenting with high gamma glutamyl transpeptidase cholestasis and/or congenital heart disease. In children it may present with decompensated cirrhosis, intellectual disability or short stature, and in adults vascular events like stroke or ruptured berry aneurysm are more commonly noted. Liver transplantation (LT) is indicated in children with cholestasis progressing to cirrhosis with decompensation. Other indications for LT include intractable pruritus, recurrent fractures, hepatocellular carcinoma and disfiguring xanthomas. Due to an increased risk of renal impairment noted in ALGS, these patients would require optimized renal sparing immunosuppression in the post-transplant period. As the systemic manifestations of ALGS are protean and a wider spectrum is being increasingly elucidated, a multidisciplinary team needs to be involved in managing these patients. Moreover, many basic-science and clinical questions especially with regard to its presentation and management remain unanswered. The aim of this review is to provide updated insights into the management of the multi-system involvement of ALGS.

Bone Fractures in Children With Cholestatic Liver Disease May Mimic Those Seen in Child Abuse

ABSTRACT

Certain fractures in children are highly specific for child abuse. Metabolic bone disease frequently develops in patients with cholestatic liver disease (CLD); this can result in weakened bones and a predisposition to pathologic fractures. Fractures that occur in patients with rickets and osteopenia may mimic a bone response to inflicted injury, which in children raise the concern of child abuse. Here we report a series of 15 patients with CLD who developed pathologic fractures in the setting of metabolic bone disease. During initial evaluation, the caretakers of 5 of these 15 patients were reported to child protective services and investigated for child abuse. Pediatricians should be aware that children with CLD have an increased incidence of pathologic fractures, even after the cholestasis has resolved.

Tissue Characterization by Low-Frequency Acoustic Waves Generated by a Single High-Frequency Focused Ultrasound Beam

The mechanical properties of biological tissues are fingerprints of certain pathologic processes. Ultrasound systems have been used as a non-invasive technique to both induce kilohertz-frequency mechanical vibrations and detect waves resulting from interactions with biological structures. However, existing methodologies to produce kilohertz-frequency mechanical vibrations using ultrasound require the use of variable-frequency, dual-frequency and high-power systems. Here, we propose and demonstrate the use of bursts of megahertz- frequency acoustic radiation to observe kilohertz-frequency mechanical responses in biological tissues. Femoral bones were obtained from 10 healthy mice and 10 mice in which osteoporosis had been induced. The bones' porosity, trabecular number, trabecular spacing, connectivity and connectivity density were determined using micro-computed tomography (μCT). The samples were irradiated with short, focused acoustic radiation pulses (f = 3.1 MHz, t = 15 μs), and the low-frequency acoustic response (1-100 kHz) was acquired using a dedicated hydrophone. A strong correlation between the spectral maps of the acquired signals and the μCT data was found. In a subsequent evaluation, soft tissue stiffness measurements were performed with a gel wax-based tissue-mimicking phantom containing three spherical inclusions of the same type of gel but different densities and Young's moduli, yet with approximately the same echogenicity. Conventional B-mode ultrasound was unable to image the inclusions, while the novel technique proposed here showed good image contrast.

Ex vivo vibro-acoustography characterization of osteoporosis in an experimental mice model

Background

Osteoporosis is a highly prevalent multifactorial osteometabolic disease, classically diagnosed, in vivo, by dual energy X-ray absorptiometry (DXA). This study evaluated osteoporosis, ex vivo, using vibro-acoustography (VA), an elastographic technique based on ultrasound radiation force.

Methods

Three groups of mice femurs were used: (I) control group (CG), (II) osteoporosis group (OG) and (III) treated osteoporosis group (TOG), in which the animals received pamidronate, an antiresorptive drug. Evaluation was performed in an acoustic tank, using two high frequency focused beams produced by a confocal ultrasonic transducer. A hydrophone registered the low frequency acoustic response (AR) of bone samples. We used micro-computed tomography (microCT) as the reference standard and evaluated the correlation between VA and microCT parameters.

Results

The spectral analyses of the ARs with estimated area under the curve (AUC) values (mean; st. dev.) were, respectively, 1.29e^-07 and 9.32e^-08 for the CG, 3.25e^-08 and 2.16e^-08 for the OG, and 1.50e^-07 and 8.37e^-08 for the TOG. VA differentiated the experimental groups (P<0.01) and the results were reproducible [interclass correlation coefficient (ICC): 0.43 (95% CI: 0.15-0.71)]. There was also a statistically significant association between VA and microCT connectivity (Conn.) (r=0.80; P<0.01) and connectivity density (Conn. D) (r=0.76; P<0.01).

Conclusions

These results encourage further studies aimed at evaluating the potential use of VA for the diagnosis of osteoporosis as a relatively low-cost and radiation-free alternative to DXA.

A review of long-term outcome and quality of life of patients after Kasai operation surviving with native livers

Biliary atresia (BA) is a rare neonatal cholestatic disease which leads to progressive obliterative cholangiopathy, resulting in biliary obstruction and jaundice. The standard surgical treatment is hepatoportoenterostomy (Kasai operation). Although approximately 50% of the affected infants would require liver transplantation within the first 2 years of life, the other 50% of the patients can live for years with their native liver, despite the progression of cirrhosis and chronic liver disease. Many of these patients will be affected by long-term complications such as repeated cholangitis, portal hypertension, variceal bleeding, growth problems, biochemical abnormalities, and hepatic osteodystrophy. These morbidities impose a huge impact on the quality of life of the patients and their families. Herein, we performed a comprehensive review on the clinical status and quality of life of long-term survivors of biliary atresia with their native livers, to facilitate meticulous longitudinal follow-up of these patients, and alert caregivers the probable complications to be aware of.

Hepatic Osteodystrophy: The Mechanism of Bone Loss in Hepatocellular Disease and the Effects of Pamidronate Treatment

OBJECTIVES:

The present study was designed to evaluate the bone phenotypes and mechanisms involved in bone disorders associated with hepatic osteodystrophy. Hepatocellular disease was induced by carbon tetrachloride (CCl4). In addition, the effects of disodium pamidronate on bone tissue were evaluated.

METHODS:

The study included 4 groups of 15 mice: a) C = mice subjected to vehicle injections; b) C+P = mice subjected to vehicle and pamidronate injections; c) CCl4+V = mice subjected to CCl4 and vehicle injections; and d) CCl4+P = mice subjected to CCl4 and pamidronate injections. CCl4 or vehicle was administered for 8 weeks, while pamidronate or vehicle was injected at the end of the fourth week. Bone histomorphometry and biomechanical analysis were performed in tibiae, while femora were used for micro-computed tomography and gene expression.

RESULTS:

CCl4 mice exhibited decreased bone volume/trabecular volume and trabecular numbers, as well as increased trabecular separation, as determined by bone histomorphometry and micro-computed tomography, but these changes were not detected in the group treated with pamidronate. CCl4 mice showed increased numbers of osteoclasts and resorption surface. High serum levels of receptor activator of nuclear factor-κB ligand and the increased expression of tartrate-resistant acid phosphatase in the bones of CCl4 mice supported the enhancement of bone resorption in these mice.

CONCLUSION:

Taken together, these results suggest that bone resorption is the main mechanism of bone loss in chronic hepatocellular disease in mice.

Multiple Looser zones of osteomalacia in Byler disease with associated vitamin D deficiency, phosphaturia, and elevated FGF23

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Byler disease is rare and stress fractures in this population are infrequently reported in literature.

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It is important to be aware of this complication of the disease because stress fractures can be a source of significant morbidity.

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Surveillance for osteomalacia and osteoporosis and treatment is advocated to prevent Looser zones and stress fractures in patients with Byler disease.

Introduction

Byler disease (progressive familial intrahepatic cholestasis) is associated metabolic bone disease as a consequence of chronic malabsorption.

Case presentation

A 33-year-old man with decompensated liver disease secondary to Byler disease was referred to the orthopaedic department with progressive pain over this right proximal tibia. On examination, he had an antalgic gait. Tenderness was localised to the proximal tibia just distal to the tibial tubercle and bilateral foot swelling. Radiographs showed multiple stress fractures characteristic of Looser zones at various stages of healing in both tibia, metatarsals (third, fourth, and fifth on the right side, and second and fourth on the left) and left femur. Bone mineral density was extremely low. Subsequent investigations were consistent with severe osteomalacia due to a combination of vitamin D deficiency and phosphaturia with elevated fibroblast factor 23 (FGF23). A good clinical response was achieved following supplementation with calcium 1000 mg and vitamin D 20 μg daily.

Discussion

Stress fractures are often associated with delay in diagnosis. Our patient presented to the orthopaedic service with multiple Looser zones that had not been previously detected. As expected, there was biochemical evidence of vitamin D deficiency. An unexpected finding was phosphaturia that was associated with marked elevation in FGF23, which has never been reported previously.

Conclusion

Byler disease may result in Looser zones of osteomalacia due to chronic malabsorption. Renal phosphorus wasting as a consequence of unexplained marked elevation in FGF23 is thought to have contributed to the onset of osteomalacia.

Medical status of 219 children with biliary atresia surviving long-term with their native livers: results from a North American multicenter consortium

OBJECTIVES

To examine the medical status of children with biliary atresia (BA) with their native livers after hepato- portoenterostomy (HPE) surgery.

STUDY DESIGN

The Childhood Liver Disease Research and Education Network database was utilized to examine subjects with BA living with their native livers 5 or more years after HPE and to describe the prevalence of subjects with BA with an "ideal" outcome, defined as no clinical evidence of chronic liver disease, normal liver biochemical indices (aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transpeptidase, platelet count, total bilirubin, international normalized ratio, and albumin), and normal health-related quality of life 5 or more years after HPE.

RESULTS

Children with BA (n = 219; 43% male) with median age 9.7 years were studied. Median age at HPE was 56 (range 7-125) days. Median age- and sex-adjusted height and weight z-scores at 5-year follow-up were 0.487 (IQR -0.27 to 1.02) and 0.00 (IQR -0.74 to 0.70), respectively. During the 12 preceding months, cholangitis and bone fractures occurred in 17% and 5.5%, respectively. Health-related quality of life was reported normal by 53% of patients. However, only 1.8% met the study definition of "ideal" outcome. Individual tests of liver synthetic function (total bilirubin, albumin, and international normalized ratio) were normal in 75%, 85%, and 73% of the study cohort.

CONCLUSION

Cholangitis and fractures in long-term survivors underscore the importance of ongoing medical surveillance. Over 98% of this North American cohort of subjects with BA living with native livers 5 or more years after HPE have clinical or biochemical evidence of chronic liver disease.

Bone metabolism in cholestatic children before and after living-related liver transplantation--a long-term prospective study

Bone disorders are common in children with end-stage liver diseases, especially those associated with cholestasis. Abnormal hepatocyte function, disordered vitamin D metabolism and calcium-phosphorous homeostasis, malnutrition, and immunosuppressive treatment are potential risk factors of bone tissue pathology before and after transplantation. The aim of the study was to analyze the long-term effect of successful living-related liver transplantation (LRLTx) on skeletal status and bone metabolism in cholestatic children. Eighteen cholestatic children (1.4±0.5yr old; 12 females [F]/6 males [M]) qualified for LRLTx were analyzed; 16 (5F/11M) of them participated in long-term observation (V4). Serum levels of osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP), cross-linked telopeptide of type 1 collagen (CTx), insulin-like growth factor I (IGF-I), IGF-I binding protein 3 (IGFBP-3), parathyroid hormone (PTH), 25-hydroxyvitamin D (25(OH)D), and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) were assayed before (V0) and 6mo (V1), 12mo (V2), 18mo (V3), and 4.4yr (V4) after LRLTx. Total body bone mineral content (TBBMC) and total body bone mineral density (TBBMD) were measured by dual-energy X-ray absorptiometry (DXA) at the same pattern. Before LRLTx, the OC, P1NP, CTx, IGF-I, and IGFBP-3 levels as well as TBBMC and TBBMD were decreased compared with age-matched control group. The mean serum levels of 25(OH)D and 1,25(OH)(2)D were within reference ranges from V0 to V4. After LRLTx, the OC, P1NP, CTx, IGF-I, and IGFBP-3 as well as TBBMC and TBBMD reached the age-matched reference values. At V4, the level of P1NP decreased below and the PTH increased above the reference range that coincided with reduced Z-scores of both TBBMC (-1.11±1.24) and TBBMD (-1.00±1.19). P1NP and CTx, both measured at V3, correlated with IGF-I at V2 (R=0.86, p=0.014 and R=0.78, p=0.021, respectively) and PTH at V3 for P1NP and V1 for CTx (R=0.64, p=0.048 and R=0.54, p=0.038, respectively). The TBBMC changes between V0 and V4 correlated with IGF-I (R=0.68, p=0.015) and 1,25(OH)(2)D (R=0.54, p=0.025), both assayed at V1. The change of TBBMC Z-scores between V0 and V4 correlated with P1NP at V1 (R=0.69, p=0.002). The TBBMD changes between V0 and V4 correlated with CTx at V1 (R=0.54, p=0.027) and P1NP change between V0 and V1 (R=0.51, p=0.038). In short-term observation, successful LRLTx led to bone metabolism normalization triggered by probable anabolic action of IGF-I and PTH and manifested by TBBMC and TBBMD increases. In long-term horizon, moderately impaired DXA assessed bone status coincided with disturbances in bone metabolism. Bone metabolism markers, especially P1NP and CTx, appeared to be good predictors of changes in bone status evaluated by DXA.

Endocrine and bone metabolic complications in chronic liver disease and after liver transplantation in children

With improved survival of orthotopic liver transplantation (OLT) in children, prevention and treatment of pre- and posttransplant complications have become a major focus of care. End-stage liver failure can cause endocrine complications such as growth failure and hepatic osteodystrophy, and, like other chronic illnesses, also pubertal delay, relative adrenal insufficiency, and the sick euthyroid syndrome. Drug-induced diabetes mellitus post-OLT affects approximately 10% of children. Growth failure is found in 60% of children assessed for OLT. Despite optimisation of nutrition, rarely can further stunting of growth before OLT be prevented. Catch-up growth is usually observed after steroid weaning from 18 months post-OLT. Whether growth hormone treatment would benefit the 20% of children who fail to catch up in height requires testing in randomised controlled trials. Hepatic osteodystrophy in children comprises vitamin D deficiency rickets, low bone mass, and fractures caused by malnutrition and malabsorption. Vitamin D deficiency requires aggressive treatment with ergocalciferol (D2) or cholecalciferol (D3). The active vitamin D metabolites alphacalcidol or calcitriol increase gut calcium absorption but do not replace vitamin D stores. Prevalence of fractures is increased both before OLT (10%-28% of children) and after OLT (12%-38%). Most fractures are vertebral, are associated with low spine bone mineral density, and frequently occur asymptomatically, but they may also cause chronic pain. Fracture prediction in these children is limited. OLT in children is also associated with a greater risk of developing avascular bone necrosis (4%) and scoliosis (13%-38%). This article reviews the literature on endocrine and skeletal complications of liver disease and presents preventive screening recommendations and therapeutic strategies.

Vitamin D deficiency and a CYP27B1-1260 promoter polymorphism are associated with chronic hepatitis C and poor response to interferon-alfa based therapy

BACKGROUND & AIMS

Vitamin D is an important immune modulator and preliminary data indicated an association between vitamin D deficiency and sustained virologic response (SVR) rates in hepatitis C virus (HCV) genotype 1 patients. We, therefore, performed a comprehensive analysis on the impact of vitamin D serum levels and of genetic polymorphisms with functional relevance within the vitamin D cascade on chronic hepatitis C and its treatment.

METHODS

Vitamin D serum levels, genetic polymorphisms within the vitamin D receptor and 1α-hydroxylase were determined in a cohort of 468 HCV genotype 1, 2, and 3 infected patients who were treated with interferon-alfa based regimens.

RESULTS

Chronic hepatitis C was associated with a high incidence of severe vitamin D deficiency compared to controls (25(OH)D(3)<10 ng/ml in 25% versus 12%, p<0.00001). 25(OH)D(3) deficiency correlated with SVR in HCV genotype 2 and 3 patients (50% and 81% SVR for patients with and without severe vitamin D deficiency, respectively, p<0.0001). In addition, the CYP27B1-1260 promoter polymorphism rs10877012 had substantial impact on 1,25-dihydroxyvitamin D serum levels (72, 61, and 60 pmol/ml for rs10877012 AA, AC, and CC, respectively, p=0.04) and on SVR rates in HCV genotype 1, 2, and 3 infected patients (77% and 65% versus 42% for rs10877012 AA, AC, and CC, respectively, p=0.02).

CONCLUSIONS

Chronic hepatitis C virus infection is associated with vitamin D deficiency. Reduced 25-hydroxyvitamin D levels and CYP27B1-1260 promoter polymorphism leading to reduced 1,25-dihydroxyvitamin D levels are associated with failure to achieve SVR in HCV genotype 1, 2, and 3 infected patients.

Compound Pollen Protein Nutrient Increases Serum Albumin in Cirrhotic Rats

Background

Malnutrition, especially protein-calorie malnutrition, is common in patients with liver cirrhosis. When in the status of malnutrition, the complications increase, liver function deteriorates, and the prognosis of patients with liver cirrhosis worsens. Hence, nutritional support and treatment is essential in patients with liver cirrhosis. Previous studies suggested that compound nutrition based on pollen can improve liver function, and can be a basic nutrient for patients with liver cirrhosis. However, the nutritional support based on pollen for malnutrition of cirrhotic patients needs to be further evaluated. In this study, we investigated the nutritional support of Noveliver, a new compound pollen protein nutrient, in the cirrhotic rats induced by carbon tetrachloride (CCl₄).

Methods

The cirrhotic rats induced by CCl₄ were treated with Noveliver in different doses, and treated with a regular compound pollen nutrient, untreated cirrhotic rats and normal rats were used as controls. Serum albumin were measured before and after the nutritional treatment in each group. At the same time, liver function, cytokines and pathological changes were also determined.

Results

In the second week of nutritional treatment, the levels of serum albumin in normal control group, low dose noveliver group, high dose noveliver group, compound protein pollen group and spontaneous recovery group were 35.67 ± 1.42, 33.07 ± 1.27, 32.27 ± 1.50, 30.53 ± 0.25, 24.53 ± 3.56 (g/L), respectively, the differences among the groups were significant (F = 14.007, P = 0.000); The levels of serum albumin in low dose Noveliver group, high dose Noveliver group and the compound protein pollen group were higher than that in the spontaneous recovery group (P = 0.000, 0.001, 0.003, respectively). In the second week of nutritional treatment, the serum levels of HGF in normal control group, low dose Noveliver group, high dose Noveliver group, compound protein pollen group and spontaneous recovery group were 101.55 ± 0.87, 94.62 ± 8.80, 98.94 ± 3.68, 78.77 ± 21.79, 39.52 ± 14.03 (pg/ml), respectively, the differences among the groups were significant (F = 11.12, P = 0.002); the levels of HGF in low dose Noveliver group, high dose Noveliver group and the compound protein pollen group were higher than that in spontaneous recovery group (P = 0.001, 0.000, 0.005). Histological results showed that the fibrosis in spontaneous recovery group was severer than those in low dose Noveliver group, high dose Noveliver group and compound protein pollen group.

Conclusions

Our data show that the both the Noveliver and the compound pollen protein nutrient increase the serum albumin and ameliorate malnutrition in cirrhotic rats; the recovery of serum albumin might be related to the hepatic damage repair and liver regeneration.

Low vitamin D serum level is related to severe fibrosis and low responsiveness to interferon-based therapy in genotype 1 chronic hepatitis C

25-Hydroxyvitamin D (25[OH]D) can potentially interfere with inflammatory response and fibrogenesis. Its role in disease progression in chronic hepatitis C (CHC) and its relation with histological and sustained virological response (SVR) to therapy are unknown. One hundred ninety-seven patients with biopsy-proven genotype 1 (G1) CHC and 49 healthy subjects matched by age and sex were consecutively evaluated. One hundred sixty-seven patients underwent antiviral therapy with pegylated interferon plus ribavirin. The 25(OH)D serum levels were measured by high-pressure liquid chromatography. Tissue expression of cytochrome (CY) P27A1 and CYP2R1, liver 25-hydroxylating enzymes, were assessed by immunochemistry in 34 patients with CHC, and in eight controls. The 25(OH)D serum levels were significantly lower in CHC than in controls (25.07 +/- 9.92 microg/L versus 43.06 +/- 10.19; P < 0.001). Lower levels of 25(OH)D were independently linked to female sex (P = 0.007) and necroinflammation (P = 0.04) by linear regression analysis. CYP27A1, but not CYP2R1, was directly related to 25(OH)D levels (P = 0.01), and inversely to necroinflammation (P = 0.01). Low 25(OH)D (odds ratio [OR], 0.942; 95% confidence interval [CI], 0.893-0.994) and cholesterol (OR, 0.981; 95%CI, 0.969-0.992) levels, older age (OR, 1.043; 95%CI, 1.002-1.085), high ferritin (OR, 1.003; 95%CI, 1.001-1.005), and necroinflammation (OR, 2.235; 95%CI, 1.014-4.929) were independently associated with severe fibrosis (F3-F4) by multivariate logistic analysis. Seventy patients (41%) achieved SVR. By multivariate analysis, hepatic steatosis (OR, 0.971; 95%CI, 0.944-0.999), lower cholesterol (OR, 1.009; 95% CI, 1.000-1.018), and 25(OH)D levels (OR, 1.039; 95%CI, 1.002-1.077) were independently associated with no SVR.

CONCLUSION

G1 CHC patients had low 25(OH)D serum levels, possibly because of reduced CYP27A1 expression. Low vitamin D is linked to severe fibrosis and low SVR on interferon (IFN)-based therapy.

Evaluation and management of end-stage liver disease in children

End-stage liver disease in children presents a challenging array of medical and psychosocial problems for the health care delivery team. Many of these problems are similar to those encountered by caregivers of adults with end-stage liver disease, such as the development of complications of cirrhosis, including ascites, spontaneous bacterial peritonitis, and esophageal variceal hemorrhage. However, the natural history of disease progression in children and their responses to medical therapy can differ significantly from that of their adult counterparts. Children with end-stage liver disease are especially vulnerable to nutritional compromise; if not effectively managed, this can seriously impact long-term outcomes and survival both before and after liver transplantation. Moreover, close attention must be given to vaccination status and the clinical setting at which health care is delivered to optimize outcomes and the delivery of high-quality pediatric health care. In this review, we address important components of the evaluation and management of children with chronic end-stage liver disease.

Vitamin D status in gastrointestinal and liver disease

PURPOSE OF REVIEW

The purpose of this review is to report on the vitamin D status and its relationship with bone health in individuals with gastrointestinal and liver disorders. In addition, recommendations regarding replacement and maintenance of optimal vitamin D stores, as well as the state of knowledge regarding its effect on the disease through its actions on the immune system, will be reviewed.

RECENT FINDINGS

The scientific community has revised upward the serum levels of vitamin D considered optimal, and doses of vitamin D much larger than those currently recommended may be needed to maintain these levels, especially in individuals with gastrointestinal and liver disorders. The relationship between vitamin D and bone health in this population is controversial. The role of vitamin D in the regulation of the immune system continues to be elucidated.

SUMMARY

Hypovitaminosis D is prevalent among individuals with gastrointestinal and liver disease. Although replacement and supplementation guidelines have not been well defined, practitioners should aim for a serum 25-hydroxyvitamin D level of at least 32 ng/ml. The contribution of vitamin D to the bone health of these individuals and its role in altering disease course through its actions on the immune system remain to be elucidated.

Impairment of bone mass development in children with chronic cholestatic liver disease

OBJECTIVE

To analyse aspects of mineral metabolism, bone mineral density (BMD), bone remodelling activity and serum IGF-1 levels in children with chronic cholestatic disease (CCLD).

PATIENTS AND MEASUREMENTS

A total of 13 children with chronic cholestatic liver disease (CCLD; mean age 7.2 +/- 4.8 years) and 22 control subjects (mean age 7.6 +/- 4.5 years) were studied. Serum osteocalcin, bone alkaline phosphatase (BAP), 25-hydroxyvitamin D, PTH and IGF-1 levels and urinary deoxypyridinoline were determined. BMD was measured by dual-energy X-ray absorptiometry in the lumbar spine, total hip and whole body. Lumbar spine areal BMD was converted mathematically to apparent volumetric BMD (aBMD) and corrected for the bone age of the patient.

RESULTS

Z-score of lumbar spine BMD was lower in CCLD patients than in controls and the difference was maintained when BMD was expressed as aBMD (control = 0.107 +/- 0.02 vs. CCLD = 0.092 +/- 0.02 g/cm(3), P < 0.05) and after conversion for bone age. All participants showed normal 25-hydroxyvitamin D levels, with no significant differences in serum levels of 25-hydroxyvitamin D and PTH between groups. IGF-1 levels were significantly lower in the CCLD group (control = 19.6 +/- 16.8 vs. CCLD = 6.4 +/- 7.6 nmol/l, P < 0.05) and a positive correlation was observed between whole body BMD and IGF-1 in this group.

CONCLUSIONS

These results indicate that CCLD limits bone mass gain in children. A reduction in hepatic IGF-1 production might be responsible, at least in part, for the low bone mass of these patients.

Report on the vitamin D status of adult and pediatric patients with inflammatory bowel disease and its significance for bone health and disease

Vitamin D is a hormone responsible for calcium homeostasis and essential for bone mineralization throughout the lifespan. Recent studies revealed a high prevalence of hypovitaminosis D among healthy adults and children, especially in the northern hemisphere, and a link between this condition and suboptimal bone health. Moreover, maintenance of what are today considered optimal vitamin D stores has not been achieved throughout the year with currently recommended daily intake for vitamin D. The prevalence of hypovitaminosis D is even higher among adults with inflammatory bowel disease (IBD), a situation that may be caused by malabsorption and gastrointestinal losses through an inflamed intestine, among other factors. In children with IBD, existing reports of vitamin D status are scarce. The relationship between vitamin D status and bone health, although well-established in healthy adults and children, has been controversial among adults and children with IBD, and the reasons for this have not been investigated to date. Studies in animal models of colitis and in vitro human studies support a role of vitamin D in the regulation of the immune system of the gut and the potential of vitamin D and its derivatives as therapeutic adjuncts in the treatment of IBD. This role of vitamin D has not been investigated with translational studies to date. Currently, there are no guidelines for monitoring vitamin D status, treating hypovitaminosis D, and maintaining optimal vitamin D stores in patients with IBD. These tasks may prove particularly difficult because of malabsorption and gastrointestinal losses that are associated with IBD.

Hyperbilirubinemia is not a major contributing factor to altered bone mineral density in patients with chronic liver disease

Reduced bone density is commonly encountered in patients with chronic liver disease. Prior studies have shown that unconjugated bilirubin inhibits osteoblast activity and function in vitro and in animal models of bone mineralization. To determine whether hyperbilirubinemia promotes the development of hepatic osteodystrophy, bone mineral density (BMD) was measured by dual energy X-ray absorptiometry in a cohort of 86 consecutive patients with chronic liver disease referred for liver transplant evaluation. The mean age of the study population was 52 years (range, 22-73), in which 52% were female and 90% were white. Average bone density values were significantly lower than expected for age, race, and sex, with Z-scores for the femoral neck and spine of -0.50 (95% confidence interval [CI] -0.63 to -0.37; p=0.0003) and -0.69 (95% CI -0.85 to -0.52; p=0.0001), respectively. Sixty-one subjects (71%) exhibited reduced BMD (T-score of femoral neck or spine<or=-1 standard deviation [SD] below the young-adult mean), and 18 subjects (21%) met criteria for osteoporosis (T-score<-2.5 SD). Stepwise logistic regression analyses identified significant associations between BMD and serum creatinine, alkaline phosphatase, age, and gender. On the other hand, neither unconjugated, nor conjugated, nor total serum bilirubin levels were found to predict diminished BMD. The lack of association between serum unconjugated bilirubin levels and bone mineralization was validated in hyperbilirubinemic Gunn rats, in which BMD and serum osteocalcin levels were no different than in wild-type rodents. In conclusion, the finding that serum bilirubin levels do not correlate with reduced BMD in patients with end-stage liver disease, and that chronic unconjugated hyperbilirubinemia does not lead to alterations in bone mineralization in Gunn rats, suggests that bilirubin is not a major contributing factor to hepatic osteodystrophy.

Effects of liver transplantation on the nutritional status of patients with cystic fibrosis*

The long-term effects of liver transplantation on nutritional status, body composition and pulmonary function in patients with liver disease associated with cystic fibrosis (CF) are poorly defined. We studied 15 patients with CF-associated biliary cirrhosis and severe portal hypertension. Seven underwent liver transplantation (age: 14.8 +/- 6.2 years), and eight were treated conservatively (age: 15.9 +/- 6.7 years). All patients were evaluated at baseline and thereafter yearly for a median duration of 5 years. During follow-up, transplanted patients gained weight and showed a significant increment in body mass index (P < 0.004), whereas patients without transplantation remained stable (P = 0.063). Baseline bone mineral content (dual energy X-ray absorptiometry scan) was lower than normal in all patients (more in transplanted patients) and increased in transplanted patients (P < 0.05), but not in patients without transplantation. In both groups percent body fat did not change, whereas fat free mass increased only in the transplant group (P = 0.06) (P < 0.03 versus nontransplanted patients). Only in transplanted patients' plasma concentrations of vitamin E and A increased (P < 0.05 versus nontransplanted patients). Forced espiratory volume in 1 s and forced vital capacity showed similar deterioration in transplanted and in nontransplanted patients. Liver transplantation is associated with long-term beneficial effects on the nutritional status of CF patients and seems to favor bone mineralization.

Distúrbios do eixo cálcio-PTH-vitamina D nas doenças hepáticas crônicas

Distúrbios no eixo cálcio-PTH-vitamina D são freqüentemente associados às doenças hepáticas crônicas (DHC). Já foi demonstrado que pacientes com DHC apresentam uma tendência à diminuição do cálcio e vitamina D, com aumento compensatório do PTH. Embora a diminuição da hidroxilação da vitamina D em 25 (OH) vitamina D fosse considerada o mecanismo principal destas alterações, estudos recentes vêm demonstrando que, mesmo nos estágios avançados de doença, o fígado ainda consegue manter níveis adequados de 25 (OH) vitamina D. Desta forma, outros fatores (ex: dieta inadequada, diminuição da exposição à luz solar) seriam os responsáveis pelas alterações no eixo cálcio-PTH-vitamina D. Além disso, o tratamento das DHC com glicocorticóides (fibrose cística) e ribavirina (Hepatite C) parece contribuir como agravante destes distúrbios. Por outro lado, parece ser a osteoporose, e não a osteomalácia ou o hiperparatireoidismo secundário, a principal alteração nas DHC. Assim, continua objeto de discussão o papel das alterações do eixo cálcio-PTH-vitamina D na osteodistrofia hepática.

Osseous complications of pediatric transplantation

Adult stature and peak bone mass are achieved through childhood growth and development. Multiple factors impair this process in children undergoing solid organ transplantation, including chronic illness, pretransplant osteodystrophy, use of medications with negative impact on bone, and post-transplant renal dysfunction. While growth delay and short stature remain common, the most severe forms of transplant-related bone disease, fracture and avascular necrosis, appear to have become less common in the pediatric age group. Osteopenia is very prevalent in adult transplant recipients and probably also in pediatrics, but its occurrence and sequelae are difficult to study in these groups due to methodological shortfalls of planar densitometry related to short stature and altered patterns of growth and development. Although the effect on lifetime peak bone mass is not clear, data from adult populations suggest an elevated long-term risk of bone disease in children receiving transplants. Optimal management of pretransplantation osteodystrophy, attention to post-transplant renal insufficiency among both renal and non-renal transplant patients, reduction of steroid dose in select patients, and supplementation with calcium plus vitamin D during expected periods of maximal bone loss may improve bone health. Careful research is required to determine the role of bisphosphonate therapy in pediatric transplantation.

CALCIUM AND BONE MINERAL METABOLISM IN CHILDREN WITH CHRONIC ILLNESSES

Increased longevity and improved medical management of children with chronic illnesses has led to a focus on the short- and long-term consequences of these conditions on bone health. Bone loss is influenced by diet, malabsorption, and disease-related imbalances in bone turnover. It may be exacerbated by common medications, especially corticosteroids. Assessment of bone mass and quality, calcium absorption, kinetically derived rates of bone turnover, and biochemical markers of bone turnover have increased our knowledge of the pathophysiology of bone loss in these children as well as provided insights into possible therapeutic interventions. Increased intake of calcium and vitamin D, while useful, is unlikely to prevent or resolve bone loss in many chronically ill children. Emphasis on combination of nutritional interventions with exercise and newer bone-sparing therapies may be necessary.

Rickets

Rickets, once thought vanquished, is reappearing. In some less developed countries it hardly went away. This seminar reviews the effects of genes, stage of development, and environment on clinical expression of the disease. Rickets can be secondary to disorders of the gut, pancreas, liver, kidney, or metabolism; however, it is mostly due to nutrient deficiency and we concentrate on this form. Although calcium deficiency contributes in communities where little cows' milk is consumed, deficiency of vitamin D is the main cause. There are three major problems: the promotion of exclusive breastfeeding for long periods without vitamin D supplementation, particularly for babies whose mothers are vitamin D deficient; reduced opportunities for production of the vitamin in the skin because of female modesty and fear of skin cancer; and the high prevalence of rickets in immigrant groups in more temperate regions. A safety net of extra dietary vitamin D should be re-emphasised, not only for children but also for pregnant women. The reason why many immigrant children in temperate zones have vitamin D deficiency is unclear. We speculate that in addition to differences in genetic factors, sun exposure, and skin pigmentation, iron deficiency may affect vitamin D handling in the skin or gut or its intermediary metabolism.

Treatment of Pediatric Cholestatic Liver Disease

Cholestatic liver disease affects a small percentage of children, but therapy results in millions of healthcare dollars being spent each year. Close monitoring of nutritional status, pruritus, and complications from portal hypertension should improve the patient's quality of life and survival without liver transplantation. Other comorbid conditions, such as cardiac or renal disease, must also be integrated into the care plan and will affect the overall prognosis of the patient. Portal hypertension leads to ascites, variceal hemorrhage, and infection, which can result in significant mortality if not promptly recognized and treated. Surgical shunts are being used less because the expertise to perform endoscopic sclerotherapy and endoscopic band ligation is available at most medical centers. However, many cholestatic diseases, including biliary atresia, progressive familial intrahepatic cholestasis (PFIC) I, II, and III, and Alagille syndrome, may still require liver transplantation (Table 1). The cost of this procedure can exceed several hundred thousand dollars per patient, without including the annual costs of immunosuppressant therapy and medical monitoring. Meticulous medical management of nutrition and the sequelae of portal hypertension may prolong survival and reduce the potential morbidity and mortality of liver transplantation.

Cholestatic syndromes

Further insights into the cellular and molecular mechanisms underlying hepatobiliary transport function and its regulation now permit a better understanding of the pathogenesis and treatment options of cholestatic liver diseases. Identification of the molecular basis of hereditary cholestatic syndromes will result in an improved diagnosis and management of these conditions. New insights into the pathogenesis of extrahepatic manifestations of cholestasis (eg, pruritus) have facilitated new treatment strategies. Important new studies have been published about the pathogenesis, clinical features, diagnosis, and treatment of primary biliary cirrhosis, primary sclerosing cholangitis, cholestasis of pregnancy, total parenteral nutrition-induced cholestasis, drug-induced cholestasis, and viral cholestatic syndromes.