Vitamin A toxicity and hypercalcaemia in chronic renal failure

Nutritional Characterisation of Childhood Chronic Kidney Disease: Trace Element Malnutrition in Paediatric Renal Disease (TeMPeReD) Study

BACKGROUND/OBJECTIVES

In chronic kidney disease (CKD), poor nutrition is associated with poorer clinical outcomes. There are limited data on milder stages of childhood CKD.

METHODS

This study characterised the nutritional state of a cohort of children with CKD.

RESULTS

Within the cohort (mean age 10.5 years, mean eGFR = 57 mL/min/1.73 m2), obesity defined by body mass index rates was comparable to that in the general population, but central obesity (waist-to-height ratio > 0.5) was evident in 44% of children. Although average nutrient intakes for the cohort were acceptable, there was marked variability in the risk of poor nutrient intake (

CONCLUSIONS

Much work is needed to optimise the nutritional status of children with CKD as an important modifiable risk factor for disease progression and other important outcomes.

Collapse

Key Words

• CKD
• nutritional assessment
• paediatrics

Collapse

MESH Headings

• Humans
• Child
• Renal Insufficiency, Chronic/blood
• Renal Insufficiency, Chronic/complications
• Female
• Male
• Trace Elements/blood
• Trace Elements/deficiency
• Nutritional Status
• Adolescent
• Malnutrition/epidemiology
• Malnutrition/blood
• Malnutrition/etiology
• Cohort Studies
• Dietary Fiber/administration & dosage

Collapse

Grants Collapse

Affiliation(s)

Matthew J. Harmer Southampton Children’s Hospital, Southampton SO16 6YD, UK (C.E.A.) School of Development and Health, Faculty of Medicine, University of Southampton, Southampton SO17 1BJ, UK
Stephen A. Wootton School of Development and Health, Faculty of Medicine, University of Southampton, Southampton SO17 1BJ, UK
Rodney D. Gilbert Southampton Children’s Hospital, Southampton SO16 6YD, UK (C.E.A.) School of Development and Health, Faculty of Medicine, University of Southampton, Southampton SO17 1BJ, UK
Caroline E. Anderson Southampton Children’s Hospital, Southampton SO16 6YD, UK (C.E.A.) School of Development and Health, Faculty of Medicine, University of Southampton, Southampton SO17 1BJ, UK

Collapse

Vitamin A and its influence on tumour extracellular matrix

Vitamin A is a crucial nutrient renowned for its role in visual health and cellular regulation. Its derivatives influence cell differentiation, proliferation, and tissue homeostasis, making them significant in cancer research due to their effects on both normal and tumour cells. This review explores the intricate relationship between vitamin A metabolism and the extracellular matrix (ECM) in cancer. The ECM profoundly affects tumour behaviour, including proliferation, invasion, and metastasis. Alterations in the ECM can facilitate tumour progression, and vitamin A derivatives have shown potential in modulating these changes. Through transcriptional regulation, vitamin A impacts ECM components and matrix metalloproteinases, influencing tumour dynamics. The review highlights the potential of vitamin A and its derivatives as adjunctive agents in cancer therapy. Despite promising laboratory findings, their clinical application remains limited due to challenges in translating these effects into therapeutic outcomes. Future research should focus on the modulation of retinol metabolism within tumours and the development of targeted therapies to enhance treatment efficacy and improve patient prognosis.

Assessment and management of vitamin status in children with CKD stages 2-5, on dialysis and post-transplantation: clinical practice points from the Pediatric Renal Nutrition Taskforce

Children with chronic kidney disease (CKD) are at risk for vitamin deficiency or excess. Vitamin status can be affected by diet, supplements, kidney function, medications, and dialysis. Little is known about vitamin requirements in CKD, leading to practice variation.The Pediatric Renal Nutrition Taskforce (PRNT), an international team of pediatric kidney dietitians and pediatric nephrologists, was established to develop evidence-based clinical practice points (CPPs) to address challenges and to serve as a resource for nutritional care. Questions were formulated using PICO (Patient, Intervention, Comparator, Outcomes), and literature searches undertaken to explore clinical practice from assessment to management of vitamin status in children with CKD stages 2-5, on dialysis and post-transplantation (CKD2-5D&T). The CPPs were developed and finalized using a Delphi consensus approach. We present six CPPs for vitamin management for children with CKD2-5D&T. We address assessment, intervention, and monitoring. We recommend avoiding supplementation of vitamin A and suggest water-soluble vitamin supplementation for those on dialysis. In the absence of evidence, a consistent structured approach to vitamin management that considers assessment and monitoring from dietary, physical, and biochemical viewpoints is needed. Careful consideration of the impact of accumulation, losses, comorbidities, and medications needs to be explored for the individual child and vitamin before supplementation can be considered. When supplementing, care needs to be taken not to over-prescribe. Research recommendations are suggested.

Longitudinal Plasma Metabolome Patterns and Relation to Kidney Function and Proteinuria in Pediatric CKD

Key Points

Longitudinal untargeted metabolomics. Children with CKD have a circulating metabolome that changes over time.

Background

Understanding plasma metabolome patterns in relation to changing kidney function in pediatric CKD is important for continued research for identifying novel biomarkers, characterizing biochemical pathophysiology, and developing targeted interventions. There are a limited number of studies of longitudinal metabolomics and virtually none in pediatric CKD.

Methods

The CKD in Children study is a multi-institutional, prospective cohort that enrolled children aged 6 months to 16 years with eGFR 30–90 ml/min per 1.73 m2. Untargeted metabolomics profiling was performed on plasma samples from the baseline, 2-, and 4-year study visits. There were technologic updates in the metabolomic profiling platform used between the baseline and follow-up assays. Statistical approaches were adopted to avoid direct comparison of baseline and follow-up measurements. To identify metabolite associations with eGFR or urine protein-creatinine ratio (UPCR) among all three time points, we applied linear mixed-effects (LME) models. To identify metabolites associated with time, we applied LME models to the 2- and 4-year follow-up data. We applied linear regression analysis to examine associations between change in metabolite level over time (∆level) and change in eGFR (∆eGFR) and UPCR (∆UPCR). We reported significance on the basis of both the false discovery rate (FDR) <0.05 and P < 0.05.

Results

There were 1156 person-visits (N : baseline=626, 2-year=254, 4-year=276) included. There were 622 metabolites with standardized measurements at all three time points. In LME modeling, 406 and 343 metabolites associated with eGFR and UPCR at FDR <0.05, respectively. Among 530 follow-up person-visits, 158 metabolites showed differences over time at FDR <0.05. For participants with complete data at both follow-up visits (n =123), we report 35 metabolites with ∆level–∆eGFR associations significant at FDR <0.05. There were no metabolites with significant ∆level–∆UPCR associations at FDR <0.05. We report 16 metabolites with ∆level–∆UPCR associations at P < 0.05 and associations with UPCR in LME modeling at FDR <0.05.

Conclusions

We characterized longitudinal plasma metabolomic patterns associated with eGFR and UPCR in a large pediatric CKD population. Many of these metabolite signals have been associated with CKD progression, etiology, and proteinuria in previous CKD Biomarkers Consortium studies. There were also novel metabolite associations with eGFR and proteinuria detected.

Vitamin A fortification: Recent advances in encapsulation technologies

Vitamin A is an essential micronutrient whose deficiency is still a major health concern in many regions of the world. It plays an essential role in human growth and development, immunity, and vision, but may also help prevent several other chronic diseases. The total amount of vitamin A in the human diet often falls below the recommended dietary allowance of approximately 900-1000 μ $ \umu $ g/day for a healthy adult. Moreover, a significant proportion of vitamin A may be degraded during food processing, storage, and distribution, thereby reducing its bioactivity. Finally, the vitamin A in some foods has a relatively low bioavailability, which further reduces its efficacy. The World Health Organization has recommended fortification of foods and beverages as a safe and cost-effective means of addressing vitamin A deficiency. However, there are several factors that must be overcome before effective fortified foods can be developed, including the low solubility, chemical stability, and bioavailability of this oil-soluble vitamin. Consequently, strategies are required to evenly disperse the vitamin throughout food matrices, to inhibit its chemical degradation, to avoid any adverse interactions with any other food components, to ensure the food is palatable, and to increase its bioavailability. In this review article, we discuss the chemical, physical, and nutritional attributes of vitamin A, its main dietary sources, the factors contributing to its current deficiency, and various strategies to address these deficiencies, including diet diversification, biofortification, and food fortification.

Deleterious side effects of nutritional supplements

Vitamin and mineral supplement consumption is widespread. They are taken for a variety of conditions, including dermatologic disorders. Although consumers often assume these supplements are safe, excessive consumption of supplements may have deleterious effects. Such vitamin supplements include vitamin A, niacin, biotin, vitamin D, and vitamin E, and specific mineral supplements include zinc, copper, and iron. These supplements may have a number of potential adverse effects.

Actual diet and nutritional deficiencies status in children on peritoneal dialysis at the Vietnam National Hospital of Pediatrics

Nutrition is essential for children with end-stage renal disease, especially for those suffering from peritoneal dialysis (PD). Although the number of PD children has increased annually at the Vietnam National Hospital of Pediatrics, studies about the diet and nutritional deficiencies status of PD children is still limited. The aim of this study was to describe the actual diet and status of nutritional deficiencies of PD patients. This cross-sectional study was conducted on 31 PD children aged 2-15 years old using the 24-h dietary recall and biochemical parameters in blood (albumin, hemoglobin, calcium, sodium, potassium, and chloride). The energy intake was lowest in children over 13-year-old with only 32.9% of dietary reference intakes (DRIs). Carbohydrate intake among 10-15-year-old children was 38.1% of DRIs. Daily consumption of sodium was 65.6% and 33%-35% of DRIs for children under and over three-year-old, respectively. In comparison with DRIs, daily consumption of magnesium, iron, and calcium of over 10-year-old children was lower than that of younger children. In terms of vitamins, B-group vitamins, Vitamin C achieved the recommended levels except Vitamin A (63.0%) and Vitamin D (20.0%). The prevalence of children with serum albumin concentration lower than the normal range was 45.2% and prevalence of anemia was 51.6%. The proportion of children with decreased plasma calcium, sodium, and potassium levels was 83.8%, 77.4%, and 12.9%, respectively. PD children's diet lacks energy, protein, lipid, carbohydrate, as well as micronutrients. The prevalence of nutritional deficiencies is remarkably high in PD children.

Hypervitaminosis A is prevalent in children with CKD and contributes to hypercalcemia

BACKGROUND

Vitamin A accumulates in renal failure, but the prevalence of hypervitaminosis A in children with predialysis chronic kidney disease (CKD) is not known. Hypervitaminosis A has been associated with hypercalcemia. In this study we compared dietary vitamin A intake with serum retinoid levels and their associations with hypercalcemia.

METHODS

We studied the relationship between vitamin A intake, serum retinoid levels, and serum calcium in 105 children with CKD stages 2-5 on dialysis and posttransplant. Serum retinoid measures included retinol (ROH), its active retinoic acid (RA) metabolites [all-trans RA (at-RA) and 13-cis RA] and carrier proteins [retinol-binding protein-4 (RBP4) and transthyretin (TTR)]. Dietary vitamin A intake was assessed using a food diary.

RESULTS

Twenty-five children were in CKD 2-3, 35 in CKD 4-5, 23 on dialysis and 22 posttransplant; 53 % had vitamin A intake above the Reference Nutrient Intake (RNI) value. Children receiving supplemental feeds compared with diet alone had higher vitamin A intake (p = 0.02) and higher serum ROH (p < 0.001). Notably, increased ROH was seen as early as CKD stage 2. For every 10 ml/min/1.73 m(2) fall in estimated glomerular filtration rate (eGFR), there was a 13 % increase in ROH. RBP4 levels were increased in CKD 3-5 and dialysis patients. The lowest ratios of ROH:RBP4 were seen in dialysis compared with CKD 2-3 (p = 0.03), suggesting a relative increase in circulating RBP4. Serum ROH, RBP4 and at-RA were associated with serum calcium. On multivariable analysis RBP4 levels and alfacalcidol dose were significant predictors of serum calcium (model R (2) 32 %) in dialysis patients.

CONCLUSIONS

Hypervitaminosis A is seen in early CKD, with highest levels in children on supplemental feeds compared with diet alone. Serum retinoid levels significantly predict hypercalcemia.

Hypercalcaemia secondary to hypervitaminosis a in a patient with chronic renal failure

Vitamin A toxicity is a well-described medical condition with a multitude of potential presenting signs and symptoms. It can be divided into acute and chronic toxicity. Serum vitamin A concentrations are raised in chronic renal failure even with ingestion of less than the usual toxic doses. Hypercalcaemia can occasionally be associated with high levels of vitamin A but it is rare. In this report, we describe a 67- year old female patient with chronic kidney disease who was taking vitamin A supplements for approximately 10 years. The patient had worsening of her chronic kidney disease over the last years and developed chronic hypercalcaemia. Her vitamin A level was elevated with a daily intake of 7000 IU. The vitamin A supplement was stopped. A few months later, vitamin A level diminished substantially and serum calcium levels returned to normal.

Acute myeloid leukemia in a 38-year-old hemodialyzed patient with von Hippel-Lindau disease

Von Hippel-Lindau disease (VHL disease) is a hereditary cancer predisposition syndrome caused by mutations of the von Hippel-Lindau tumor suppressor gene. The gene product, pVHL, regulates the level of proteins that play a central role in protecting cells against hypoxia. Clinical hallmarks of von Hippel-Lindau disease are the development of central nervous system hemangioblastomas, renal cell carcinoma, pheochromocytoma, neuroendocrine tumors and endolymphatic sac tumors.

In this article the case of a 38-year old hemodialyzed patient who became ill with acute myeloid leukemia (AML) three years after being diagnosed with von Hippel-Lindau disease is presented.

After cytostatic treatment the patient went into complete hematologic remission but there was still residual disease at the genetic level. After consolidation therapy patient developed bone marrow aplasia and severe pneumonia. Despite intensive treatment the patient died from acute respiratory failure.

In this paper we present for the first time a case of von Hippel-Lindau disease associated with acute myeloid leukemia. No evidence of relationship between VHL disease and blood cancers has been demonstrated so far. Despite the fact that there is an increased risk of cancer development in hemodialyzed patients, cancer is a relatively rare cause of death in the dialysed population, and the most common malignancies are genitourinary cancers. It seems likely that development of acute myeloid leukemia in patient with VHL disease can be related to epigenetic alterations of the VHL gene, but further studies are needed.

Serum retinol, retinol-binding protein, and transthyretin in children receiving dialysis

OBJECTIVE

We investigated the relationships of retinol (ROH), retinol-binding protein (RBP), and transthyretin (TTR) in children with end-stage renal disease (ESRD). Our hypothesis was that levels of ROH and RBP would be elevated in children with ESRD.

METHODS AND PATIENTS

We measured ROH, RBP, and TTR serum concentrations in a group of pediatric ESRD patients biannually. Children were grouped according to age and method of dialysis, i.e., hemodialysis (HD) or peritoneal dialysis (PD): HD1, aged <12 years (n = 8); PD1, aged <12 years (n = 19); HD2, aged >or=12 years (n =19); and PD2, aged >or=12 years (n = 29).

RESULTS

No differences in ROH, RBP, TTR, or their ratios were found as a function of type of dialysis in groups PD2 and HD2. The ROH and TTR were significantly higher in PD1 than HD1 (P = .01 and P = .003, respectively). No correlations were evident between ROH and RBP or TTR with length of time on dialysis, serum calcium, or serum creatinine, except for group PD2, in which ROH was positively correlated with RBP (P = .025). There were no significant differences among any of the ratios in terms of age or method of dialysis.

CONCLUSIONS

The data indicate that children with ESRD exhibit elevated levels of serum ROH, RBP, and TTR, in proportions similar to those reported in the adult ESRD literature. Further study is needed to clarify the consequences of increased ROH in uremic children.

Successful treatment by all-trans retinoic acid in a patient with acute promyelocytic leukemia complicated by liver cirrhosis and polycystic kidney

Although all-trans retinoic acid (ATRA) is widely used in acute promyelocytic leukemia (APL), there is little data as to whether or not ATRA is useful for patients with liver and renal failure. A 63-year-old APL patient, complicated by Child-Pugh class A liver cirrhosis and chronic renal failure (creatinine 3.2 mg/dL), was successfully treated with 45 mg/m(2)/day of ATRA. With three courses of chemotherapy, complete remission has been maintained for four years in this patient. Serum trough and maximum ATRA concentration, and the area under the curve (AUC) were not elevated. These observations suggest that full-dose ATRA therapy might be safely applicable to such a complicated case with APL.

An anti-inflammatory and antioxidant nutritional supplement for hypoalbuminemic hemodialysis patients: a pilot/feasibility study

BACKGROUND

A low serum albumin concentration < 3.8 g/dL, a marker of malnutrition-inflammation complex syndrome, is observed in approximately half of all maintenance hemodialysis (MHD) patients in the United States and is strongly associated with increased mortality.

OBJECTIVES

We hypothesized that a novel oral nutritional intervention with anti-inflammatory and antioxidant properties taken during routine dialysis sessions is well tolerated and corrects hypoalbuminemia in MHD patients.

DESIGN

Controlled clinical study.

SETTING

An outpatient dialysis facility affiliated with a tertiary care community medical center with six equally distributed hemodialysis shifts and 163 MHD patients.

PATIENTS

Among all MHD outpatients of three selected HD shifts (n = 81 patients), 21 subjects had a serum albumin level < 3.8 g/dL. One patient who was hospitalized before the intervention was excluded. The other three dialysis shifts, with 82 MHD outpatients including 20 hypoalbuminemic subjects, were observed as concurrent controls.

INTERVENTION

The nutritional intervention included one can of Oxepa and one can of Nepro to be taken together orally during each routine hemodialysis session for 4 weeks. Each can contains 237 mL fluid. Oxepa provides 355 calories and 14.8 g protein per can, includes maltodextrin, medium-chain triglycerides, borage oil, and refined and deodorized fish oil, and is designed for critically ill patients with inflammation and oxidative stress. Each can of Oxepa includes 1,020 mg gamma-linolenic acid, 3,100 mg caprylic acid, 1,080 mg eicosapentaenoic acid, 75 mg taurine, 2,840 IU vitamin A activity, 75 IU vitamin E, and 200 mg vitamin C. Nepro provides 475 calories and 16.7 g protein per can; includes high-oleic safflower oil, corn syrup solids, and fructo-oligosaccharides; and is tailored for the nutritional needs of MHD patients. Oxepa and Nepro also contain L-carnitine, 43 mg and 62 mg, respectively.

MAIN OUTCOME MEASURES

Serum albumin pretrial and posttrial.

RESULTS

Studied outpatients (12 men and 8 women) were aged 60.4 +/- 13.0 (SD) years. Three patients had started MHD treatment between 1.5 and 3 months before the intervention. Nine patients were diabetic. Preintervention serum albumin, 3.44 +/- 0.34 g/dL (mean +/- SD) increased to 3.68 +/- 0.34 g/dL (P = .001) 4 weeks after the start of the intervention. In 16 patients, serum albumin level increased by 0.2 to 1.3 g/dL, whereas in 4 patients the serum albumin level decreased by 0.2 to 0.6 g/dL. Three patients reported diarrhea, and one diabetic patient had increased serum glucose values. No other side effects were noted. In 20 control outpatients not receiving nutritional intervention, serum albumin did not change from 3.46 +/- 0.20 to 3.47 +/- 10.44 g/dL (P = .47).

CONCLUSIONS

In hypoalbuminemic MHD patients, a short-term in-center nutritional intervention with one can of Nepro and one can of Oxepa during HD is practical, convenient, well-tolerated, and associated with a significant increase in serum albumin level. Well-designed randomized placebo-controlled clinical trials are needed to verify the safety and effectiveness of this nutritional intervention and its impact on clinical outcome in hypoalbuminemic MHD patients.

Trace elements and vitamins in maintenance dialysis patients

Although protein-energy malnutrition occurs commonly in patients with end-stage renal disease undergoing maintenance dialysis treatment, it is not the only form of malnutrition that may exist in these individuals. They may also suffer from deficiencies of micronutrients, particularly trace elements and vitamins. More commonly occurring vitamin deficiencies in maintenance dialysis patients include those for vitamin C (ascorbate), folate, vitamin B6 (pyridoxine), and 1,25-dihydroxycholecalciferol (calcitriol). Among trace elements, deficiencies may occur more commonly for iron, zinc, and possibly selenium, whereas toxicities are more common with aluminum and possibly copper. Evidence suggests that there is an abnormally high prevalence of antioxidant deficiency in maintenance dialysis patients, especially because a low intake of protein and energy may be associated with inadequate ingestion of antioxidant vitamins (ie, vitamins E and C and carotenoids). Thus, some micronutrient deficiencies in maintenance dialysis patients may contribute to the development of atherosclerotic cardiovascular disease. Dietary requirements for vitamins and trace elements in maintenance dialysis patients are reviewed and the recommended daily intakes are discussed.

Relationship of serum antioxidant vitamins to serum creatinine in the US population

Several small clinical studies have reported that serum vitamin A levels were higher but serum vitamin C levels were lower among patients with end-stage renal disease. However, the relationship of antioxidant vitamins to renal function has not been studied in the general population. We examined the relationship of serum antioxidant vitamin levels to serum creatinine levels and risk for hypercreatininemia in a representative sample of 6,629 non-Hispanic whites, 4,411 non-Hispanic blacks, and 4,480 Mexican Americans aged 18 years or older who participated in the Third National Health and Nutrition Examination Survey. Serum antioxidant vitamins were measured by isocratic high-performance liquid chromatography, and serum creatinine levels, by the modified kinetic Jaffé method. Serum vitamin A level was positively and significantly associated with serum creatinine level, whereas serum vitamin C level was inversely and significantly associated with serum creatinine level. A one-SD higher level of serum vitamin A (16.9 microg/dL) was associated with a 2.53-fold (95% confidence interval, 1.96 to 3.27; P < 0.001), 2.07-fold (95% confidence interval, 1.84 to 2.33; P < 0.001), and 2.76-fold (95% confidence interval, 1.74 to 4.37; P < 0.001) greater risk for hypercreatininemia among non-Hispanic whites, non-Hispanic blacks, and Mexican Americans, respectively. A one-SD higher serum vitamin C level (0.45 mg/dL) was associated with a 22% (95% confidence interval, 0.06 to 0.35; P = 0.01) and 42% (95% confidence interval, 0.08 to 0.62; P = 0.02) lower risk for hypercreatininemia in non-Hispanic whites and Mexican Americans. Our study provides useful information to support the hypothesis that antioxidant vitamins may have an important role in the pathogenesis of chronic renal failure.

Use of medicines by older people in a large British national survey, and their relation to vitamin status indices

OBJECTIVE

To describe the extent of use of medicines by older people living in Britain, and to explore relationships with vitamin status indices.

DESIGN

The National Diet and Nutrition Survey of people aged 65 years and over collected data from a British sample during 1994-95. The present study has made novel use of it, to relate medicine use with biochemical indices of vitamin status.

SETTING

Eighty postcode areas, selected randomly from mainland Britain.

SUBJECTS

1506 people, 65 years and over gave information about use of medication, and a 4-day weighed food record. Three-quarters gave blood for status indices.

RESULTS

78% of those living in the community and 93% of those in institutions were using medication. Certain vitamin status indices: plasma retinol, erythrocyte folate and riboflavin, paradoxically suggested better status in users than in non-users of antihypertensive, gastrointestinal, central nervous system, corticosteroid or diabetic drugs. There was evidence of a link with renal insufficiency, especially for plasma retinol, but neither this nor increased nutrient intake, acute phase effects or haemoconcentration could explain the paradoxical associations.

CONCLUSIONS

Caution is needed in interpreting certain vitamin status indices, especially in older people who are extensively using medicines. New vitamin indices are needed, to avoid confounding interferences.

Racial group differences in plasma concentrations of antioxidant vitamins and carotenoids in hemodialysis patients

Approximately 50% of the mortality in hemodialysis patients is due to cardiovascular disease. Antioxidant vitamins and carotenoids may be protective because oxidation of low-density lipoproteins appears to be a necessary prerequisite for the development of atherogenesis, and hemodialysis itself may stimulate the generation of oxygen reactive species. African Americans comprise a substantial proportion of dialysis patients because they have higher rates of hypertension, glomerulonephritis, and diabetic end-stage renal disease than do whites. The purpose of this cross-sectional study was to determine the plasma concentrations of antioxidant vitamins and carotenoids in hemodialysis patients and to investigate whether differences in these concentrations in the major racial or ethnic groups exist. Plasma concentrations of alpha- and gamma-tocopherol, carotenoids, and retinol were measured with HPLC and plasma vitamin C was measured with a spectrophotometric method in 109 white and African American hemodialysis patients. Dietary intakes of selected micronutrients were also compared by using data from a food-frequency questionnaire. Overall, plasma vitamin C and alpha-tocopherol concentrations were comparable but plasma carotenoid concentrations were lower than those reported for other populations. African American patients had significantly higher mean plasma concentrations of retinol (P < 0.04), lutein (P < 0.02), and total carotenoids minus lycopene (P < 0.04); whites had significantly higher mean plasma concentrations of alpha-tocopherol (P < 0.02), independent of age and plasma lipid concentrations. Diabetes comorbidity had an independent negative association with plasma beta-carotene concentration but was not associated with other measures.

[Vitamin A poisoning revealed by hypercalcemia in a child with kidney failure]

BACKGROUND

Patients with chronic renal failure are at risk of vitamin A intoxication, a risk that must be evoked when unexplained hypercalcemia occurs.

CASE REPORT

An 8 year-old boy with Alagille syndrome and chronic renal failure was admitted because of general deterioration, and bone pain. Severe hypercalcemia (3.9 mmol/L) was present. Serum phosphate, parathyroid hormone and 25 OH D3 levels were normal; 1-25 (OH)2 D3 levels were undetectable. Hypercalcemia was attributed to vitamin A intoxication, due to the administration of a mean daily dose of 12000 IU of vitamin A for at least 2 years. The diagnosis was confirmed by high plasma levels of retinol (1475 micrograms/L). Hypercalcemia only partially responded to treatment with bisphosphonates, calcitonin and dialysis with low calcium dialysate. Serum vitamin A levels remained elevated one month after vitamin A withdrawal. The boy died two months after admission from atrioventricular block.

CONCLUSION

Vitamin A administration induces a high risk of intoxication in patients with chronic renal failure. Serum vitamin A concentrations are elevated in these patients, because of decreased renal metabolism of retinol, and vitamin A supplements must be avoided.

Hypervitaminosis A in two hemodialysis patients

We present two cases of hemodialysis patients developing vitamin A toxicity related to excessive consumption of nutritional supplements containing large quantities of vitamin A. In one patient, severe hypercalcemia was the lone presenting sign; in the other, hypercalcemia was associated with unusual neurologic manifestations. We will discuss the reason why hemodialysis patients are at special risk for the development of hypervitaminosis A and review the mechanism leading to the associated hypercalcemia.

Micronutrition in dialysis

A variety of dialysis methods are currently used in the treatment of renal failure. Nutrition support modalities are also frequently used for patients with renal failure who are malnourished or at risk of becoming malnourished. The effects of various dialysis methods on certain micronutrient levels and needs have generally not been extensively studied, however, this article reviews information that has been published regarding carnitine, water soluble vitamin, fat soluble vitamin, and trace element levels during dialysis. Recommendations for provision of micronutrients during dialysis are provided.

Intracellular actions of vitamin A

Because the effects of vitamin A vary with tissue type and often with the form of vitamin A itself, a complete understanding of the mechanism(s) of action still has not been attained. The action of vitamin A may be at the level of genomic expression, at the membrane level, or both. Intercellular and intracellular transport of vitamin A are facilitated by specific binding proteins but probably not in the cellular uptake of vitamin A. Subcellularly, vitamin A may exert a direct effect on transit through the Golgi apparatus, as observed from both biochemical and morphological studies. In my laboratory, recent work using cell-free systems has shown that retinol stimulates transition vesicle formation from endoplasmic reticulum in a GTP-requiring step.

Retinol, supplemental vitamin A and bone status

Studies of hypervitaminosis A in animals and anecdotal reports of accidental vitamin A poisoning in humans suggest impairment of bone remodeling and increased numbers of fractures. Because of the widespread use of high-dose vitamin A supplements which may produce subclinical hypervitaminosis associated with decreased bone mass and increased risk of fracture, we studied the relationship between current vitamin A supplement use, serum retinol levels, radial bone mass and fracture history in a geographically-defined population of 246 postmenopausal women, 55-80 years of age. More than 36% of this population used a vitamin A supplement with 8% of these consuming an amount in excess of 2000 retinol equivalents (RE)/day. Serum retinol was measured using high-pressure liquid chromatography and radial bone mass was measured using single photon absorptiometry. After controlling for age, current estrogen replacement, and current thiazide antihypertensive use, we observed no statistically significant relationship between vitamin A supplement use or serum retinol with radial bone mass or fractures.

Vitamin supplementation of patients receiving haemodialysis

In order to assess the necessity of vitamin supplementation for patients who are receiving haemodialysis, measurements of vitamin status were made, and both dietary and supplementary intakes were assessed, in 26 patients who were undergoing haemodialysis. Blood samples were collected from these patients before they underwent haemodialysis, after an overnight fast, for the measurement of plasma retinol, alpha-tocopherol and ascorbate levels. Serum and erythrocyte folate levels were measured also. Thiamin status was assessed by the effect of added thiamin pyrophosphate on erythrocyte transketolase activity and pyridoxine status was assessed by the effect of added pyridoxal-5'-phosphate on erythrocyte aminotransferase activity. All patients had elevated plasma retinol levels; 48% of patients had elevated plasma alpha-tocopherol levels; the plasma ascorbate level was low in 50% of patients but was elevated in 25% of patients; and plasma and erythrocyte folate levels were elevated in 76% and 91% of patients, respectively. Thiamin status was normal in all but one patient and the pyridoxine level appeared to be low in two other patients. Many patients had low dietary intakes of vitamin C, folate and vitamin B6. We conclude that supplements of vitamins A and E are not required and, when dietary intakes of water-soluble vitamins are marginal, these should be supplemented at a dose as near as possible to the recommended dietary intake.

Studies of the spontaneous transfer of retinol from the retinol:retinol-binding protein complex to unilamellar liposomes

The transfer of retinol from its complex with the retinol-binding protein to cell surfaces was studied using unilamellar liposomes as a cell surface model. The transfer of retinol to liposomes at 37 degrees C was rapid and reached an apparent equilibrium within 60 min. The amount of retinol transferred to the liposomes at equilibrium was directly proportional to the starting concentration of retinol:retinol-binding protein over a wide range of retinol:retinol-binding protein concentrations and also directly proportional to the concentration of liposomal phospholipid in the system, when the concentration of retinol:retinol-binding protein was held constant. The transfer increased slightly with temperature. Transfer was increased by a factor of 1.8 at pH 4.5 compared to pH around 7. Prealbumin in amounts sufficient to complex all retinol:retinol-binding protein, decreased retinol transfer to liposomes indicating that prealbumin increases the affinity of retinol-binding protein for retinol. Addition of apo retinol-binding protein to the system decreased the transfer of retinol to liposomes considerably probably through competition with the liposomes for retinol. In similarly designed experiments delipidated bovine serum albumin competed much less with liposomes for retinol. The results show that spontaneous transfer of retinol from the retinol:retinol-binding protein complex to liposomal membranes occurs in vitro and suggests that a similar transfer may occur in vivo from retinol:retinol-binding protein to cell surface membranes.

Systemic lupus erythematosus, renal disease, hemodialysis and vitamin A

Recent studies indicate that clinically-active systemic lupus erythematosus (SLE) is uncommon in patients with end-stage renal disease undergoing long-term hemodialysis. Several lines of indirect evidence suggest that the dialysis procedure itself may be responsible for inducing remission; that SLE could reflect a toxicity reaction to excessive tissue levels of vitamin A; and that remission associated with dialysis may be due to a gradual reduction in vitamin A levels at the sites of SLE activity.

Pibloktoq (hysteria) and Inuit nutrition: possible implication of hypervitaminosis A

The hysterical reaction among Eskimo peoples known as pibloktoq, one of a group of aberrant behaviors occurring among Arctic and Circumarctic societies termed 'arctic hysterias', has been explained by a variety of theories: ecological, nutritional, biological-physiological, psychological-psychoanalytic, social structural and cultural. This study hypothesizes the possible implication of vitamin intoxication, namely, hypervitaminosis A, in the etiology of some cases of pibloktoq. Its biocultural approach implicates elements of several explanatory classes, which are not mutually exclusive. Experimental and clinical studies of nonhumans and humans reveal somatic and behavioral effects of hypervitaminosis A which closely parallel many of the symptoms reported for Western patients diagnosed as hysterical and Inuit sufferers of pibloktoq. Eskimo nutrition provides abundant sources of vitamin A and lays the probable basis in some individuals for hypervitaminosis A through ingestion of livers, kidneys, and fat of arctic fish and mammals, where the vitamin often is stored in poisonous quantities. Possible connections between pibloktoq and hypervitamonosis A are explored. A multifactorial framework may yield a more compelling model of some cases of pibloktoq than those that are mainly unicausal, since, among other things, the disturbance has been reported for males and females, adults and children, and dogs.

Effects of diet and nutrition on drug therapy

Foods containing biochemically active substances have been used therapeutically throughout the ages and continue to function as important adjuncts to drug therapy. But naturally-occurring substances can also have adverse effects, as can the food additives of today. Food--drug interactions can alter the effect of therapeutic agents or cause adverse reactions where none had existed. These problems are often aggravated in elderly patients, who may suffer from malnutrition (e.g., protein insufficiency) or altered food metabolism. Malnutrition in the elderly can be caused by disease, socioeconomic factors, or simply by the deterioration of eating habits. Although nutritional requirements decrease with age, the elderly still need nutrients for the repair of normal structures and for energy. The nutritional needs of the elderly remain poorly defined. Drugs can alter food metabolism, which, in turn, can affect drug action. Many food--drug interactions are well documented; drug absorption and drug elimination are often affected by an altered food metabolism. Particular problems include salicylate-induced iron deficiency, poor monitoring of vitamin metabolism and the effects of vitamin underuse and overuse, and lack of knowledge about the effects of long-term drug use on vitamin metabolism. An additional problem is the presence of potentially harmful materials in non-prescription products.