Bone disease in chronic childhood cholestasis. II. Better absorption of 25-OH vitamin D than vitamin D in extrahepatic biliary atresia

Chenodeoxycholic acid regulates fibroblast growth factor 23 gene expression via estrogen-related receptor γ in human hepatoma Huh7 cells

Fibroblast growth factor 23 (FGF23) is a glycoprotein that belongs to the FGF19 subfamily and participates in phosphate and vitamin D homeostasis. Chenodeoxycholic acid (CDCA), one of the primary bile acids, is reported to induce the secretion of FGF19 subfamily members, FGF21 and FGF19, in hepatocytes. However, whether and how CDCA influences FGF23 gene expression are largely unknown. Thus, we performed real-time polymerase chain reaction and Western blot analyses to determine the mRNA and protein expression levels of FGF23 in Huh7 cells. CDCA upregulated estrogen-related receptor γ (ERRγ) alongside FGF23 mRNA and protein levels, while, the knockdown of ERRγ ablated the induction effect of CDCA on FGF23 expression. Promoter studies showed that CDCA-induced FGF23 promoter activity occurred partly through ERRγ binding directly to the ERR response element (ERRE) in the human FGF23 gene promoter. Finally, the inverse agonist of ERRγ, GSK5182 inhibited the induction of FGF23 by CDCA. Overall, our results revealed the mechanism of CDCA-mediated FGF23 gene upregulation in the human hepatoma cell line. Moreover, the ability of GSK5182 to reduce CDCA-induced FGF23 gene expression might represent a therapeutic strategy to control abnormal FGF23 induction in conditions that involve elevated levels of bile acids, such as nonalcoholic fatty liver disease and biliary atresia.

Fat Soluble Vitamin Assessment and Supplementation in Cholestasis

Malnutrition in children with chronic cholestasis is a prevalent issue and a major risk factor for adverse outcomes. Fat soluble vitamin (FSV) deficiency is an integral feature of cholestatic disease in children, often occurring within the first months of life in those with neonatal cholestasis and malnutrition. This review focuses on FSVs in cholestasis, with particular emphasis on a practical approach to surveillance and supplementation that includes approaches that account for differing local resources. The overarching strategy suggested is to incorporate recognition of FSV deficiencies in cholestatic children in order to develop practical plans for close monitoring and aggressive FSV repletion. Routine attention to FSV assessment and supplementation in cholestatic infants will reduce long periods of inadequate levels and subsequent adverse clinical sequalae.

Massive infection of Cystidicoloides ephemeridarum in brown trout Salmo trutta with skeletal deformities

We investigated the cause of skeletal deformities found in brown trout from the Aspromonte mountain area in Reggio Calabria, Italy. Toxicological, histopathological and parasitological analyses were carried out on 14 fish with evident macro-morphological alterations from 2 different locations in the same river, and 4 control fish without morphological alterations from a different river (far from the first river but still within the area under study). Histopathological and radiological observations confirmed severe skeletal deformities in the specimens investigated. Parasitological examinations highlighted the presence of the nematode Cystidicoloides ephemeridarum, found only within the gastrointestinal tract of specimens showing deformities. Moreover, a direct correlation between parasite number and fish size was found. Given the low heavy metal levels and the presence of a massive parasitosis in teleosts showing deformities, we postulate a correlation between skeletal deformities and nematode infestation: the parasites caused a serious vitamin and mineral deficiency in the fish, which led to a dysplastic vertebral column. The low calcium levels found in malformed specimens compared with negative controls effectively confirm this hypothesis.

Impaired Bone Health in Children With Biliary Atresia

OBJECTIVES

The aim of the study was to examine the frequency of rickets and bone fractures and to assess areal bone mineral density (aBMD) in childhood among patients with biliary atresia (BA).

METHODS

We gathered data on all patients diagnosed with BA in Finland that survived to ≥1 year of age between 1 January 2000 to 30 June 2018. Data on gestational age, birth weight, postsurgical medications, and history of rickets and bone fractures were collected retrospectively. Serum levels of 25-hydroxyvitamin D [25(OH)D] postportoenterostomy (PE) were collected. Plain radiographs and dual energy X-ray absorptiometry (DXA) measurements of study subjects were reviewed.

RESULTS

Out of 49 patients, 7 (14%) were diagnosed with rickets during infancy. Clearance of jaundice [odds ratio 0.055, 95% confidence interval [CI] 0.00266-0.393; P < 0.01] was a protective factor against rickets. Sufficient 25(OH)D levels were reached 3 months post-PE. Eleven (22%) patients suffered at least one bone fracture (range 1-9) during childhood and adolescence. In DXA measurements, median lumbar spine aBMD anthropometrically adjusted z-scores were as follows: in native liver survivors 0.8 (interquartile range [IQR] -1.9 to 1.4) at 5 and -0.3 (IQR -1.3 to 0.8) at 10 years and for liver transplanted patients 0.4 (IQR -0.2 to 1.1) at 5 and 0.6 (IQR -0.1 to 1.3) at 10 years.

CONCLUSIONS

BA patients have an increased risk for rickets and bone fractures compared with the normal population. Most BA patients have aBMD within normal range between 5 and 10 years of age irrespective of liver transplantation status.

Nutrition Support of Children With Chronic Liver Diseases: A Joint Position Paper of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition

Chronic liver disease places patients at increased risk of malnutrition that can be challenging to identify clinically and treat. Nutrition support is a key aspect of the management of these patients as it has an impact on their quality of life, morbidity, and mortality. There are significant gaps in the literature regarding the optimal nutrition support for patients with different types of liver diseases and the impact of these interventions on long-term outcomes. This Position Paper summarizes the available literature on the nutritional aspects of the care of patients with chronic liver diseases. Specifically, the challenges associated with the nutritional assessment of these subjects are discussed, and recently investigated approaches to determining the patients' nutritional status are reviewed. Furthermore, the pathophysiology of the malnutrition seen in the context of chronic liver disease is summarized and monitoring, as well as treatment, recommendations are provided. Lastly, suggestions for future research studies are described.

Factors influencing the absorption of vitamin D in GIT: an overview

Vitamin D refers to a group of secosteroid compounds and recognized as the antirachitic vitamin, as it counters rickets, mineral desorption from fully-grown bones (Osteodistrophy), bone, joint disorders, and fragility of bones. On one hand, there is scarcity of vitamin D rich food while on other hand a number of factors negotiate its absorption efficiency in human gastrointestinal tract (GIT). These factors include variations in the physiochemical state of the vitamin D (molecular forms, potency and their physiological linkages), the complexity of food matrix (the amount and type of fatty acids, dietary fibers and presence/absence of vitamin D enhancer and inhibitor), and its interaction of other fat soluble compounds with vitamin D as well as the host-associated factors (age, disease, surgery, obesity, genetic variation etc.). It is hypothesized that the bioavailability of vitamin D in GIT is compromised if there changes within these factors. Present article is intended to review the contribution of these factors anticipated to be influencing vitamin D absorption in GIT.

Two Case Reports of FGF23-Induced Hypophosphatemia in Childhood Biliary Atresia

Cholestatic liver disease has long been associated with childhood rickets, secondary to impaired absorption of fat-soluble vitamin D. Elevated serum levels of fibroblast growth factor 23 (FGF23), secondary to genetic defects or tumor-induced osteomalacia, causes hypophosphatemic rickets in childhood. We present 2 infants with end-stage liver disease due to biliary atresia (BA) who developed hypophosphatemia with renal phosphate wasting. Serum FGF23 levels were elevated more than 8 times the upper limit of normal, and the older infant showed radiographic evidence of rickets. Both infants required large supplements of phosphate in addition to calcitriol. Following liver transplantation, FGF23 normalized in both patients and phosphate and calcitriol supplementation were discontinued. Immunohistochemistry revealed ectopic overexpression of FGF23 by hepatocytes in the BA liver. These observations highlight a unique cause of hypophosphatemic rickets in childhood and suggest the need for further investigation into the relationship between BA and other cholestatic disorders, and bone metabolism.

Vitamin D Levels in Infants With Biliary Atresia: Pre- and Post-Kasai Portoenterostomy

OBJECTIVES

Infants with biliary atresia (BA) are at high risk of vitamin D deficiency. We aimed to determine the prevalence and factors influencing vitamin D levels at presentation and post-Kasai portoenterostomy (KPE).

METHODS

Single-centre retrospective review of infants with BA who underwent KPE. Pre- and postoperatively 25-hydroxyvitamin D (25-OHVD), liver and bone biochemistry data were collected. 25-OHVD levels <10 and 10 to 20 ng/mL were defined as vitamin D "deficiency" and "insufficiency," respectively.

RESULTS

One hundred twenty-nine infants with BA (isolated n = 101, developmental n = 28, and white n = 79; non-white n = 50) were included in this study. At presentation, 75 of 92 (81%) were vitamin D deficient and only 1 infant had a level >20 ng/mL. Median 25-OHVD levels were 5(2-23), 17(2-72), 15(2-80), 17(2-69), and 23(2-98) ng/mL at pre-KPE, 1, 4, 6, and 12 months postoperation. There was no difference in 25-OHVD levels between the isolated and developmental groups with BA. Pre-KPE, white infants had significantly higher levels than non-white infants (6[2-23] vs 3[2-14] ng/mL, P = 0.01). Post-KPE 25-OHVD levels correlated well with liver and bone biochemical variables (eg, at 6 months: bilirubin rs = -0.34; P < 0.001, alkaline phosphatase rs = -0.46; P < 0.00001, and phosphate rs = 0.49; P < 0.00001).

CONCLUSIONS

25-OHVD deficiency is invariable at presentation in infants with BA, irrespective of its likely aetiology, and is more severe in non-white infants. Despite routine parenteral and enteral supplementation, low 25-OHVD levels persist post KPE especially in icteric infants. More aggressive vitamin D supplementation and monitoring in this population is paramount.

Vitamin D bioavailability: state of the art

There has been renewed interest in vitamin D since numerous recent studies have suggested that besides its well-established roles in bone metabolism and immunity, vitamin D status is inversely associated with the incidence of several diseases, e.g., cancers, cardio-vascular diseases, and neurodegenerative diseases. Surprisingly, there is very little data on factors that affect absorption of this fat-soluble vitamin, although it is acknowledged that dietary vitamin D could help to fight against the subdeficient vitamin D status that is common in several populations. This review describes the state of the art concerning the fate of vitamin D in the human upper gastrointestinal tract and on the factors assumed to affect its absorption efficiency. The main conclusions are: (i) ergocalciferol (vitamin D2), the form mostly used in supplements and fortified foods, is apparently absorbed with similar efficiency to cholecalciferol (vitamin D3, the main dietary form), (ii) 25-hydroxyvitamin D (25OHD), the metabolite produced in the liver, and which can be found in foods, is better absorbed than the nonhydroxy vitamin D forms cholecalciferol and ergocalciferol, (iii) the amount of fat with which vitamin D is ingested does not seem to significantly modify the bioavailability of vitamin D3, (iv) the food matrix has apparently little effect on vitamin D bioavailability, (v) sucrose polyesters (Olestra) and tetrahydrolipstatin (orlistat) probably diminish vitamin D absorption, and (vi) there is apparently no effect of aging on vitamin D absorption efficiency. We also find that there is insufficient, or even no data on the following factors suspected of affecting vitamin D bioavailability: (i) effect of type and amount of dietary fiber, (ii) effect of vitamin D status, and (iii) effect of genetic variation in proteins involved in its intestinal absorption. In conclusion, further studies are needed to improve our knowledge of factors affecting vitamin D absorption efficiency. Clinical studies with labeled vitamin D, e.g., deuterated or (13)C, are needed to accurately and definitively assess the effect of various factors on its bioavailability.

HDR syndrome in a Japanese girl with biliary atresia: a case report

Background

Hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome is an autosomal dominant disorder. We report the first detailed case of hypoparathyroidism complicated by biliary atresia.

Case presentation

A 1-year-old Japanese girl was admitted to our hospital for living donor liver transplantation. She suffered from obstructive jaundice owing to biliary atresia. She also had persistent hypocalcemia. Despite oral calcium and abundant vitamin D supplementation, a laboratory test showed hypocalcemia (1.4 mmol/l) and hyperphosphatemia (2.6 mmol/l). The intact parathyroid hormone level was normal (66 ng/l) with severe vitamin D deficiency (25-hydroxy vitamin D: undetectable levels). There were no rachitic changes in metaphysis on X-rays. Her family history showed that her mother had sensorineural deafness, a low serum calcium level (2.1 mmol/l), hypoplastic left kidney, and a past history of an operation for right vesicoureteral reflux. We suspected that this patient and her mother have hypoparathyroidism, sensorineural deafness, and renal dysplasia syndrome. A heterozygous GATA3 gene mutation (c.736delGinsAT) was found in this patient and her mother, but not in her father.

Conclusion

This familial case confirms the importance of family history in the diagnosis of HDR syndrome. Regardless of marked vitamin D deficiency, the complication of hypoparathyroidism prevented the onset of vitamin D deficiency rickets in our patient.

Efficacy of fat-soluble vitamin supplementation in infants with biliary atresia

OBJECTIVE

Cholestasis predisposes to fat-soluble vitamin (FSV) deficiencies. A liquid multiple FSV preparation made with tocopheryl polyethylene glycol-1000 succinate (TPGS) is frequently used in infants with biliary atresia (BA) because of ease of administration and presumed efficacy. In this prospective multicenter study, we assessed the prevalence of FSV deficiency in infants with BA who received this FSV/TPGS preparation.

METHODS

Infants received FSV/TPGS coadministered with additional vitamin K as routine clinical care in a randomized double-blinded, placebo-controlled trial of corticosteroid therapy after hepatoportoenterostomy (HPE) for BA (identifier NCT 00294684). Levels of FSV, retinol binding protein, total serum lipids, and total bilirubin (TB) were measured 1, 3, and 6 months after HPE.

RESULTS

Ninety-two infants with BA were enrolled in this study. Biochemical evidence of FSV insufficiency was common at all time points for vitamin A (29%-36% of patients), vitamin D (21%-37%), vitamin K (10%-22%), and vitamin E (16%-18%). Vitamin levels were inversely correlated with serum TB levels. Biochemical FSV insufficiency was much more common (15%-100% for the different vitamins) in infants whose TB was ≥2 mg/dL. At 3 and 6 months post HPE, only 3 of 24 and 0 of 23 infants, respectively, with TB >2 mg/dL were sufficient in all FSV.

CONCLUSIONS

Biochemical FSV insufficiency is commonly observed in infants with BA and persistent cholestasis despite administration of a TPGS containing liquid multiple FSV preparation. Individual vitamin supplementation and careful monitoring are warranted in infants with BA, especially those with TB >2 mg/dL.

Bone health in a nonjaundiced population of children with biliary atresia

Objectives. To assess bone health in a cohort of nonjaundiced children with biliary atresia (BA) and the effect of growth and development on bone outcomes. Methods. Children ages one to eighteen years receiving care from Children's Hospital of Philadelphia were recruited. Each child was seen once and assessed for growth, pubertal development, concurrent medications, bilirubin, ALT, albumin, vitamin D status, bone mineral density (BMD), and bone mineral content (BMC) of the lumbar spine and whole body. Results. BMD declined significantly with age, and upon further analysis with a well-phenotyped control cohort, it was found that BMC was significantly decreased for both lumbar spine and whole body, even after adjustment for confounding variables. An age interaction was identified, with older subjects having a significantly greater impairment in BMC. Conclusions. These preliminary results demonstrate that children with BA, including those without jaundice, are likely to have compromised bone health even when accounting for height and puberty, which are common confounding factors in chronic disease. Further investigation is needed to identify the determinants of poor bone mineral status and to develop strategies to prevent osteoporosis later in life.

Recent advances in biliary atresia: prospects for novel therapies

BACKGROUND

Biliary atresia (BA) is a progressive fibro-obliterative disease of the extrahepatic biliary tree that presents with biliary obstruction before 2 months of age. Untreated BA is a uniformly fatal disease and even with our current therapies only 50% of children with BA will be transplant-free by 2 years of age. Despite descriptions of this disorder dating back to the 1800s our current therapies are palliative. They focus on prompt diagnosis, supportive nutritional care and interventions for sequelae.

OBJECTIVE

To present the literature supporting current treatment strategies and potential future therapies.

METHOD

Each of the aspects of care is described and the literature about nuances of care is provided.

CONCLUSION

Therapies will not improve outcomes until novel treatments are introduced, such as those suggested, which may intervene in the inflammatory or fibrotic steps of the disease process.

Liver transplantation for progressive familial intrahepatic cholestasis: clinical and histopathological findings, outcome and impact on growth

In this study, we analyze the demographic features, clinical and histopathological findings in patients who underwent liver transplantation for progressive familial intrahepatic cholestasis. We also analyze outcome and impact of liver transplantation on growth and bone mineral content. Most of the patients were presented with jaundice mainly beginning within the first six months. At the time of initial admission; eight patients had short stature (height SD score<2), and four patients had weight SD score<2. Liver transplantation were performed at the age of 43.2+/-27 months (range 9 to 96 months), 6.5+/-3.5 months later after the first admission. Infection, surgical complications and osmotic diarrhea associated with severe metabolic acidosis were noted in 41.4%, 16.6% and 33.3%, respectively. One patient developed posttransplant lymphoproliferative disorder. Overall; 1 year graft and patient survival was 69.2% and 75%, respectively. At the end of the 1st year only 2 patients had height SD score<2. Linear regression of height gain against increase in total body BMD measured at the time of transplantation and 1 year after liver transplantation gave a coefficient r=0.588 (p=0.074). No correlation was found between the height gain and age and PELD score at time of transplantation, and no difference was noted between the sexes and donor type. Liver transplantation is effective treatment modality with good outcome and little morbidity, and increases the growth acceleration in patients with PFIC associated with cirrhosis.

Hypovitaminosis D in acutely injured pediatric burn patients

PROBLEM

The prevalence of vitamin D insufficiency, its etiology, and associated sequelae among acutely injured burn patients is unknown.

OBJECTIVE

This study assessed vitamin D and endocrine status, as well as the effect of anabolic agents, in pediatric patients who had sustained burns in excess of 25% total body surface area (TBSA).

SUBJECTS

Sixty-nine patients with a mean TBSA burn of 50.6+/-2.2% (range 27% to 94%) and full thickness injury of 41.3+/-3.0% (range 0% to 94%) were studied. Subjects ranged in age from 0.6 to 18 years (mean, 5.8+/-0.6 years). Main outcome measures Blood samples were obtained for serum 25-hydroxyvitamin D (D25), 1,25-dihydroxyvitamin D (D1,25), albumin, cortisol, triiodothyronine (T3), tetraiodothyronine (T(4)), thyroid stimulating hormone (TSH), and parathormone (PTH).

RESULTS

Two hundred eighty morning blood samples of D25 and D1,25 demonstrated that 45% and 26.2% were low and 8.9% and 11% were very low, respectively. At least one low D25 or D1,25 level occurred in 62.3% of all subjects. Very low levels were noted in 23.2% of all patients. There was an increased incidence of hyperparathyroidism in patients with very low serum D25. Vitamin D25 and D1,25 levels were lower in subjects with larger burns or inhalation injury, as well as those treated with thyroxine or oxandrolone. Serum albumin, cortisol, T(4), and TSH were not correlated with concentration of vitamin D.

CONCLUSIONS

Demonstration of a high incidence of low serum vitamin D indicates vitamin D status may be significantly compromised in burned children. It is unclear why vitamin D deficiency exists in this population. The most effective way to improve vitamin D status remains elusive at this time.

Biliary atresia

BA is a rare disease of unclear etiology; nevertheless, its impact in the field of pediatric hepatology is significant. It is the most common surgically correctable cause of neonatal cholestasis and is the most common pediatric disease referred for liver transplantation. Little progress has been made with regard to improving outcome or understanding its pathogenesis in the past decade. Fortunately, however, a national, government-sponsored collaborative endeavor has begun that will hopefully make a significant impact upon the progress of designing new treatments for BA and develop a better understanding of its pathogenesis.

Bone mineral density and height gain in children with chronic cholestatic liver disease undergoing transplantation

BACKGROUND

Osteodystrophy is a well-described complication of chronic liver disease. Previous reports in adults and children undergoing liver transplantation (LT) were discordant, with the former showing no improvement of bone disease in the first year after transplantation and the latter demonstrating remarkable benefit from it. Our aim was to perform a pilot study on osteodystrophy in children undergoing LT and evaluate the contribution of growth on bone mineral density (BMD) changes.

METHODS

We studied six patients (two male), with a median age at transplantation of 8.8 (range 3.8-16.6) years. Indications for transplantation were biliary atresia and progressive familial intrahepatic cholestasis (three patients each). BMD was studied with dual-energy x-ray absorptiometry and biochemical markers of liver and bone function in patients before and at 3, 6, and 12 months after LT.

RESULTS

Median L2-L4 spinal BMD was 0.54 g/cm2 (range 0.29-0.87) before LT, and 0.58 g/cm2 (0.27-0.86) at 3 months, 0.66 g/cm2 (0.36-1.00) at 6 months, and 0.76 g/cm2 (0.44-1.02) at 12 months after LT (P=0.005). Median height was 133 (range 93-167) cm before LT, and 134 (93-167) at 3 months, 136 (97-167) at 6 months, and 139 (102-167) at 12 months after LT. There was direct correlation between height gain and total body BMD improvement (r=0.929, P=0.007).

CONCLUSION

BMD in children with chronic cholestatic liver disease improves remarkably by 12 months after LT. Catch-up growth in children can account for the different effect of LT on bone density between adult and pediatric populations in the first year after surgery.

End-stage Liver Disease in Children

The treatment of children with end-stage liver disease involves the coordinated management of nutritional deficiencies, ascites, pruritus, encephalopathy, and portal hypertension. The implementation of management strategies depends upon a parent or guardian to administer the plan in the context of a child at different stages of developmental, physiologic, emotional, and physical maturity. Fat-soluble vitamins (A, D, E, and K) and micronutrient levels should be monitored routinely and supplemented if deficient. In some patients, supplemental nutrition to provide additional energy and protein is needed to ensure optimal growth and development. Ascites often respond to spironolactone and sodium restriction, but may require the addition of a loop diuretic or even abdominal paracentesis. Pruritus significantly impairs the quality of life of patients and is typically treated with ursodeoxycholic acid, rifampin, or an antihistamine. Partial biliary diversion, or liver transplant in some instances, is necessary for patients with self-mutilating pruritus that results from intrahepatic cholestasis. Hepatic encephalopathy is poorly defined in infants and small children. Elevated serum ammonia serves as a surrogate marker for encephalopathy, which is treated with dietary protein restriction and lactulose. The usefulness of medical prophylaxis for esophageal varices has been noted in adults, though such studies have not been performed in children. If variceal bleeding becomes problematic, treatment with endoscopic variceal banding or sclerotherapy is indicated. A surgical shunt to reduce portal pressure is needed in some cases. Orthotopic liver transplant ultimately may be necessary to overcome the unrelenting consequences of end-stage liver disease.

Extrahepatic biliary atresia in a border collie

Progressive lameness and leg pain were the predominant clinical signs in a 17-week-old male border collie presented for examination. On clinical investigation, extrahepatic cholestasis in association with rickets due to inadequate vitamin D resorption was diagnosed. The dog was treated parenterally with vitamin D and a cholecystoduodenostomy was performed. At 25 days postsurgery the lameness had resolved and bone structure was radiographically normal. However, at six weeks postsurgery, the dog's condition deteriorated rapidly and euthanasia was finally performed at eight weeks postsurgery. At postmortem examination, Toxocara canis nematodes were found to have invaded the biliary system via the anastomosis between the gallbladder and duodenum, causing biliary and hepatic toxocariasis. The cause of the primary extrahepatic cholestasis was atresia of the common bile duct at the hepatic end. The liver tissue showed microscopic lesions of chronic extrahepatic cholestasis as well as acute inflammation associated with the nematode invasion. There was no postmortem evidence of bone lesions. Extrahepatic biliary atresia is extremely rare in animals and has not been described before in dogs. In contrast, it represents the most common cause of congenital cholestasis in children, occurring in approximately one per 10,000 to 15,000 live births.

The role of magnesium in the pathogenesis of bone disease in childhood cholestatic liver disease: a preliminary report

BACKGROUND

Magnesium deficiency may contribute to the metabolic bone disease that complicates chronic cholestatic liver disease. We hypothesized that magnesium deficiency alters vitamin D metabolism by decreasing parathyroid hormone (PTH) response, resulting in decreased serum osteocalcin and decreased bone accretion.

METHODS

Nine subjects, age 3-22 years, with cholestatic liver disease were evaluated with the magnesium retention test. The response of PTH, 1,25(OH)2 vitamin D, and osteocalcin to provocative stimuli and dual x-ray absorptiometry measurement of bone mineral density (BMD) of the lumbar spine were assessed. Thereafter, subjects were treated with oral magnesium supplements.

RESULTS

All nine subjects were magnesium depleted. Repletion with magnesium was successful in seven subjects, and required 4 to 31 (median 14) months with doses of 6 to 34 (median 11) mg/kg/day. Baseline serum PTH was significantly reduced in the cholestatic subjects compared to 15 age-matched controls. Comparison of baseline to repleted provocative testing was performed in six Mg-repleted subjects. Osteocalcin response increased significantly (p = 0.048) with repletion, while PTH response increased (p = 0.061). Lumbar spine BMD increased modestly with repletion (p = 0.093).

CONCLUSIONS

This preliminary report suggests that magnesium depletion is extremely common in children with chronic cholestasis. We speculate that magnesium supplementation may be warranted to forestall the progression of metabolic bone disease in chronic cholestasis.

Nutritional considerations and management of the child with liver disease

Nutritional management of the infant and child with liver disease is highly dependent upon the type of liver disease. Acute liver disease, such as that secondary to viral hepatitis, requires no specific nutritional therapy with the exception that branched-chain amino acid supplements may be indicated in the management of hepatic encephalopathy. Nutritional management of the child with chronic liver disease depends upon whether or not cholestasis is present, since in that condition, large amounts of fat-soluble vitamin supplements and medium-chain triglycerides are usually required for optimum growth. However, anicteric cirrhotic liver disease also presents nutritional challenges because of hypermetabolism, enteropathy, and increased protein oxidation. Certain inborn errors of metabolism that result in liver disease (including galactosemia, hepatorenal tyrosinemia, hereditary fructose intolerance, and Wilson's disease) have specific nutritional requirements. And, finally, the advent of pediatric liver transplantation has placed new emphasis on the importance of optimum nutritional management of the child with chronic liver disease, since improvement of nutritional status in the pretransplant period maximizes success of the transplant. This review will focus on the pathogenesis of malnutrition in childhood liver disease and will provide recommendations for nutritional assessment and monitoring as well as nutritional management of cholestatic liver disease, anicteric cirrhotic liver disease, and the inborn errors of metabolism enumerated above. Specific recommendations for nutritional management of the child awaiting liver transplantation will be provided.

Intestinal transport of calcium in rat biliary cirrhosis

The characteristics of intestinal calcium transport in chronic cholestasis remain largely unknown. Using an experimental model of biliary cirrhosis in the rat, we aimed to investigate changes in calcium transport at the jejunal and ileal levels. Two methods were used: 1) uptake of 45Ca in brush border membrane vesicles and 2) measurements of transepithelial fluxes of calcium in Ussing chambers. Thirty days postsurgery, cholestatic rats presented biliary cirrhosis, with normal growth, normal daily energy, and calcium intakes, but had depressed circulating levels of 25-(OH)-vitamin D2 and 1,25-(OH)-vitamin D3. Compared with sham-operated controls, 45Ca uptake ([Ca2+] = 0.03 mmol) measured in vesicles from cholestatic rats was decreased by 3-fold in the duodenojejunum, in concordance with a lower content in brush border membrane calmodulin. Other changes in brush border membrane composition included decreases in structural proteins, microvillous enzymes, and in triglyceride content. Transepithelial fluxes of calcium measured in the ileum ([Ca2+] = 1.2 mmol) revealed in controls a net basal secretion flux (Jnet = -30.4 +/- 8.1 mmol.h-1.cm-2) that was reduced by 3-fold (p < 0.05) in vitamin D-deficient rats (Jnet = -10.4 +/- 4.8 mmol.h-1.cm-2). In response to 25-(OH)-vitamin D2 treatment, calcium uptake rates increased by 40% in the jejunum, whereas in the ileum, the secretion flux returned to basal control levels. Oral administration of taurocholate or tauroursodeoxycholate (50 mmol) depressed almost completely calcium uptake capacity in the duodenojejunum. By complexing free calcium, tauroconjugated bile acids inhibited in vitro calcium uptake proportionally to their concentration in the medium (0-40 mmol). Our data indicate that, in rat biliary cirrhosis, transport capacity of calcium in the duodenojejunum is markedly reduced in association with vitamin D deficiency and alterations in brush border membrane composition.

Vitamin A status in biliary atresia: intestinal absorption and liver storage of retinol

The vitamin A status of 19 patients with corrected biliary atresia was examined. They had been receiving 5,000 IU of oral vitamin A daily postoperatively. Plasma vitamin A levels in the nonjaundiced group were almost within normal range, whereas those in the jaundiced group were significantly low compared with the controls. In the oral vitamin A tolerance test, plasma vitamin A levels increased from 33.1 +/- 11.8 to 215.4 +/- 100.7 micrograms/dL in the nonjaundiced group, and from 23.1 +/- 10.3 to 209.8 +/- 154.2 micrograms/dL in the slightly jaundiced group, at 4 hours after the administration of vitamin A, showing no difference between both group and control. In the severely jaundiced group, plasma vitamin A levels increased from 13.5 +/- 3.5 to 30.0 +/- 14.6 micrograms/dL, a significantly smaller increase compared with controls. However, liver vitamin A levels were greater than 20 micrograms/g liver in all patients, irrespective of the presence of jaundice. This study suggested that nutritional support to facilitate the synthesis of retinol-binding protein may be an important factor in addition to vitamin A supplementation.

Vitamin D metabolism in pre-operative extrahepatic biliary atresia

In order to clarify the pathogenesis of rickets in preoperative patients with extrahepatic biliary atresia, we evaluated baseline serum 25-OHD and 1,25(OH)2D levels and correlated serum 25-OHD levels with increase in age and season of birth in 16 preoperative patients. Further, parenteral vitamin D2 tolerance tests were performed in 5 cases. Serum 25-OHD and 1,25(OH)2D levels were significantly lower than those in 15 normal controls. There was a negative correlation between the serum 25-OHD levels and increase in age. The patients born during the winter had lower serum 25-OHD concentrations than those born in summer. The mean value of increased 25-OHD levels after the parenteral vitamin D2 tolerance tests did not differ from that of 6 controls. Since there was no impairment of vitamin D 25-hydroxylation, the reduction in serum 25-OHD may therefore be mainly due to disturbed intestinal vitamin D absorption. It was also concluded that season of birth and increase in age are pathogenic factors in the etiology of rickets in preoperative patients with extrahepatic biliary atresia.

Calcium absorption in bone disease associated with chronic cholestasis during childhood

Fractional absorption of calcium was determined in 9 children aged 4.9 to 16.9 yr with chronic cholestatic liver disease to determine the role of calcium malabsorption in the development of metabolic bone disease. Radiological evidence of rickets was absent in all patients, but bone density, measured by single beam photon absorptiometry of the distal radius, was reduced in eight of nine subjects. Serum calcium and phosphorus concentrations were normal in all except one subject. Serum 25-hydroxyvitamin D concentration was decreased compared with controls in only one of nine patients, but serum 1,25-dihydroxyvitamin D concentrations were diminished in seven of nine subjects. In all subjects, dietary calcium and phosphorus intakes were greater than 80% of the RDA. Fractional absorption of calcium, determined by oral and intravenous administration of stable calcium isotopes, was similar in cholestatic compared with control subjects (37.1% +/- 12.5% vs. 34.0% +/- 16.4%). In the cholestatic subjects, calcium absorption correlated with serum 1,25-dihydroxyvitamin D (r = 0.871, p less than 0.002) but not 25-hydroxyvitamin D concentrations. Calcium balance, assessed by the duplicate diet method, was positive in four of five subjects. Anthropometric measurements were performed to examine the relationship between nutritional status and bone mineral content. Heights of all subjects were less than or equal to the 10th percentile and fat stores and somatic protein stores were less than the 25th percentile in six of nine subjects. We conclude that factors other than calcium malabsorption and decreased serum 25-hydroxyvitamin D concentration contribute to diminished bone mass in children with cholestatic liver disease.