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Nutritional vitamin D deficiency rickets in Sudanese children.

Nutritional vitamin D deficiency rickets was established in 41 Sudanese children aged from 3 months to 7 years by clinical, radiological and therapeutic response supported by biochemical investigations. There were 25 boys and 16 girls, of whom 42% were infants of less than 1 year. Forty-seven per cent of rachitic children were underweight. Six infants had early rickets with no bony swellings but had other clinical features and radiological evidence of rickets. One of them, aged 3 months, presented with hypocalcaemic convulsions. Three children had icthyosis. Serum alkaline phosphatase was raised in 75%, hypophosphataemia occurred in 68% and hypocalcaemia in 54% of patients. Anaemia, mostly hypochromic, was detected in 79%. Possible causes were poor socio-economic background, inadequate dietary intake in both mothers and children, prolonged breastfeeding, prematurity, limited sun exposure and type of residence. Nutritional vitamin D deficiency rickets should be looked for in Sudanese children, especially in preterms and in those living in flats.

Age Distribution↗

Nutritional rickets in suburbia.

OBJECTIVE: Vitamin D deficiency continues to be a problem in pediatrics. This report presents four children, one Caucasian male and three African-American females aged 4 to 24 months who were treated for vitamin D deficiency rickets. METHODS: One female was diagnosed in the Emergency Department during evaluation of a viral syndrome, another presented with hypocalcemic seizures and the third was a self-referral for evaluation of widened wrists. The male had biochemical rickets discovered incidentally during a hospitalization for pneumonia. All were breastfed without formula supplements. The 24-month female had severe cow and soy protein allergies and received multivitamin supplements intermittently. Birth order was from third to sixth child. Two families practiced Islam and the mothers wore veils. The females had a weight deficit for height. The females demonstrated a rachitic rosary, widening of the wrists and leg bowing. At diagnosis the serum calcium was 5.0-8.6 mg/dl, the inorganic phosphorus was 1.5-3.9 mg/dl and the alkaline phosphatase was 408-3324 U/L. The serum intact parathormone levels and the vitamin D levels were measured at Nichols Laboratories. The 25-OH vitamin D levels were 2-22 ng/ml and the 1,25(OH)2 vitamin D levels were 14-122 pg/ml. All had elevated parathormone levels. The three females had roentgenographic evidence of rickets. Two of the children also demonstrated iron deficiency. RESULTS: All patients responded to Vitamin D supplements, beginning at 2000 IU for the male and 8,000-10,000 IU daily for the females. Two children were also given calcium supplements. The three females all showed complete healing of the rickets radiologically within six months. The serum intact parathormone demonstrated an inverse correlation with the serum calcium during recovery (r=-0.669; p<0.05). CONCLUSION: Vitamin D deficiency does still occur. Breastfed children of multiparous mothers, with increased skin pigmentation, living in the higher latitudes are at increased risk and would benefit from vitamin D supplementation while breastfeeding.

Alkaline Phosphatase↗

Hereditary hypophosphatemic rickets with hypercalciuria is caused by mutations in the sodium-phosphate cotransporter gene SLC34A3.

Hypophosphatemia due to isolated renal phosphate wasting results from a heterogeneous group of disorders. Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is an autosomal recessive form that is characterized by reduced renal phosphate reabsorption, hypophosphatemia, and rickets. It can be distinguished from other forms of hypophosphatemia by increased serum levels of 1,25-dihydroxyvitamin D resulting in hypercalciuria. Using SNP array genotyping, we mapped the disease locus in two consanguineous families to the end of the long arm of chromosome 9. The candidate region contained a sodium-phosphate cotransporter gene, SLC34A3, which has been shown to be expressed in proximal tubulus cells. Sequencing of this gene revealed disease-associated mutations in five families, including two frameshift and one splice-site mutation. Loss of function of the SLC34A3 protein presumably results in a primary renal tubular defect and is compatible with the HHRH phenotype. We also show that the phosphaturic factor FGF23 (fibroblast growth factor 23), which is increased in X-linked hypophosphatemic rickets and carries activating mutations in autosomal dominant hypophosphatemic rickets, is at normal or low-normal serum levels in the patients with HHRH, further supporting a primary renal defect. Identification of the gene mutated in a further form of hypophosphatemia adds to the understanding of phosphate homeostasis and may help to elucidate the interaction of the proteins involved in this pathway.

Animals↗

Nutritional rickets: deficiency of vitamin D, calcium, or both?

Nutritional rickets remains a public health problem in many countries, despite dramatic declines in the prevalence of the condition in many developed countries since the discoveries of vitamin D and the role of ultraviolet light in prevention. The disease continues to be problematic among infants in many communities, especially among infants who are exclusively breast-fed, infants and children of dark-skinned immigrants living in temperate climates, infants and their mothers in the Middle East, and infants and children in many developing countries in the tropics and subtropics, such as Nigeria, Ethiopia, Yemen, and Bangladesh. Vitamin D deficiency remains the major cause of rickets among young infants in most countries, because breast milk is low in vitamin D and its metabolites and social and religious customs and/or climatic conditions often prevent adequate ultraviolet light exposure. In sunny countries such as Nigeria, South Africa, and Bangladesh, such factors do not apply. Studies indicated that the disease occurs among older toddlers and children and probably is attributable to low dietary calcium intakes, which are characteristic of cereal-based diets with limited variety and little access to dairy products. In such situations, calcium supplements alone result in healing of the bone disease. Studies among Asian children and African American toddlers suggested that low dietary calcium intakes result in increased catabolism of vitamin D and the development of vitamin D deficiency and rickets. Dietary calcium deficiency and vitamin D deficiency represent 2 ends of the spectrum for the pathogenesis of nutritional rickets, with a combination of the 2 in the middle.

Calcium↗

Research on the probable cause of an outbreak of field rickets in turkeys.

An outbreak of field rickets in turkeys prompted studies on the cause. In Experiment 1, there were four treatments with two replicate pens of 10 poults per pen. The treatments consisted of poults fed newly manufactured feed (control), poults fed a diet containing control feed and 5% clean litter, poults fed control feed and 5% litter from the pens of affected poults, and poults challenged with an intestinal homogenate by gavage. Field rickets did not develop with these treatments. The feed was suspect, and, in Experiment 2, poults were either fed the suspect feed or newly manufactured feed. There were four replicate pens of 25 poults per pen. Poults fed the suspect feed had a decrease (P < or = 0.05) in BW at 1, 2, 3, and 4 wk of age; an increase in the relative weight of the liver, pancreas, kidney, and bursa of Fabricius; and a decrease in bone ash. There were changes in clinical chemistries. In the third study, there were five dietary treatments with two replicate pens of 25 poults per treatment. The treatments consisted of poults fed newly manufactured feed; new feed mixed with 25, 50, or 75% suspect feed; or 100% suspect feed. Body weights of poults fed 100% suspect feed were decreased at 2, 3, and 4 wk as was the relative weight of the liver, pancreas, and bursa of Fabricius. The relative weight of the kidney increased. Lameness, a decrease in bone ash, and changes in hematology and blood chemistry were observed in the poults consuming 100% suspect feed. These data demonstrate that feed from the original outbreak could induce field rickets and was toxic. Because the feed contained adequate vitamin D, calcium, and phosphorus, the cause of this outbreak of field rickets is thought to be a toxic feed contaminant affecting bone development.

Alkaline Phosphatase↗

Rickets and protein malnutrition in northern Nigeria.

The aim of the study was to explore the relationship between protein nutritional status and the development of rickets in children living in northern Nigeria. The diagnosis of rickets in 16 children between the ages of 10 months and 7 years was confirmed using established, and recently developed clinical and biochemical parameters. Twenty-seven children devoid of skeletal stigmata were age- and sex-matched to the rachitic patients. A battery of clinical laboratory and anthropometric measurements designed to assess calcium homeostasis, skeletal growth, the extent of bone remodeling or resorption, and protein nutritional status were performed on all subjects. Our central finding was that although the rachitic children were moderately malnourished, their protein nutritional status was significantly better as measured by the serum prealbumin concentration (15.4 v. 12.5 mg/dl, P = 0.0012) when compared with the severely malnourished children who were devoid of any indication of rickets. This may be due, in part, to the fact that actively growing children are more likely to develop rickets than are children whose linear growth is impeded. Unexpectedly, we found that the mean concentrations of serum 1,25-dihydroxyvitamin D in both the rachitic and control group were higher than any values for the active vitamin D metabolite previously reported in the literature.

Albumins↗

Aminoaciduria in calcium-deficiency rickets in northern Nigeria.

Generalized aminoaciduria is associated with vitamin D-deficiency rickets in humans, but there is little information regarding aminoaciduria in rickets caused by primary calcium deficiency. In contrast to rickets in other parts of the world, this bone disease in Nigeria is caused primarily by inadequate intake of dietary calcium. We conducted a clinical trial in Jos, Nigeria in 10 children with radiographically and biochemically proven rickets; an equal number of non-rachitic healthy children from the same area served as controls. Serum and 24 h urine samples were obtained at baseline and at 24 h, 1 week, 4 weeks, and 12 weeks after initiation of calcium supplementation (1000 mg/day) and were analysed for their content of amino acids. Serum calcium, phosphorus, intact parathyroid hormone (PTH), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were also measured at each time point. In the rachitic subjects urinary amino acid concentrations were elevated from 2- to 16-fold at baseline, while serum amino acid levels increased 1.5- to 3.8-fold compared to controls. After 12 weeks of calcium supplementation, serum and urine amino acids decreased. There was no correlation between the degree of aminoaciduria and serum PTH or 1,25-dihydroxyvitamin D concentrations. We conclude that the aminoaciduria in these rachitic children was related to their calcium status and not to their vitamin D or PTH status.

Amino Acids↗

Nutritional rickets without vitamin D deficiency in Bangladesh.

To understand nutritional rickets in Bangladesh better, 14 rachitic and 13 'unaffected' children were evaluated. Seventy per cent of children with active rickets had no evidence of either vitamin D deficiency or familial rickets. Rickets in Bangladesh is probably related to calcium deficiency. Abnormalities in 'unaffected' children suggest that subclinical calcium insufficiency is common.

Bangladesh↗

Radiographic scoring method for the assessment of the severity of nutritional rickets.

Radiographic changes of rickets are well characterized, but no method of grading the severity of these changes has been in general use. Consequently, it is difficult to compare objectively or follow radiographic improvement. We prospectively evaluated the utility and reproducibility of a scoring method for measuring the severity of rickets. A 10-point score for radiographs of wrists and knees was devised to assess the degree of metaphyseal fraying and cupping and the proportion of the growth plate affected. The score progresses in half point increments from zero (normal) to 10 points (severe). Four trained physicians independently scored radiographs on two separate occasions from 67 children with active rickets. A broad representation of mean radiographic scores was moderately correlated with alkaline phosphatase (r = 0.58). Interobserver correlation of radiographic scores was 0.84 or greater for all observer pairs and intraobserver correlation was 0.89 or greater for each observer. Researchers and clinicians should find the score useful to assess objectively the severity of rickets.

Alkaline Phosphatase↗

Rickets in premature infants fed different formulas.

To study the role of formula as a cause of rickets, we randomly assigned 46 very-low-birth-weight (VLBW) infants (less than or equal to 1,500 gm) to one of three groups receiving either Isomil, a soy isolate formula, Similac with Iron, a common milk-based formula, or Similac 24 LBW, a hypercaloric milk-based formula designed for low-birth-weight infants during the first three to four months of life. Postnatal changes in serum calcium, phosphorus, alkaline phosphatase, and albumin were monitored during this study. Radiologic diagnosis of rickets was made in 60% of infants fed Isomil and 5% fed Similac with Iron. Significantly low levels of serum phosphorus and high levels of serum alkaline phosphatase were also seen in infants fed Isomil. The exact cause of the biochemical changes and the high incidence of rickets among infants fed Isomil is not clear. Poor solubility and possibly the decreased bioavailability of minerals in soy isolate formula may be important. We conclude that rickets occurs with high frequency among VLBW infants fed soy isolate, but not milk-based formulas. We suggest that prolonged feeding of soy isolate formulas should be avoided in VLBW infants.

Alkaline Phosphatase↗

Genetic causes of rickets.

Dietary deficiency of vitamin D, genetic disorders of its bioactivation to 1,25-dihydroxyvitamin D [1,25(OH)2D], or disorders of vitamin D action can cause rickets. The rate-limiting, hormonally-regulated, biologically activating step in the synthesis of 1,25(OH)2D is the 1 alpha-hydroxylation of 25-hydroxyvitamin D, which occurs in kidney and other tissues and is mediated by a mitochondrial cytochrome P450 enzyme, P450c1 alpha. After many years of effort, the cDNA and gene for this enzyme were cloned in late 1997. Mutations in the P450c1 alpha gene, located on chromosome 12, cause 1 alpha-hydroxylase deficiency, also known as vitamin D-dependent rickets type I, an autosomal recessive disease characterized by rickets and impaired growth due to failure of renal synthesis of 1,25(OH)2D. X-linked hypophosphatemic rickets, a dominantly inherited disease, is caused by mutations in the PHEX gene, whose function in regulating renal phosphate and vitamin D metabolism remains to be elucidated.

Avitaminosis↗

Genetic linkage studies of X-linked hypophosphataemic rickets in a Saudi Arabian family.

UNLABELLED: OBJECTIVE, PATIENTS AND DESIGN: X-linked hypophosphataemic rickets (HYP) is the most common inherited form of rickets and the gene causing this disorder has been localized to Xp22.3-p21.3 by linkage studies of affected families of Northern European origin. In addition, the locus order Xpter-(DXS207-DXS43,DXS197)-HYP-DXS41-X cen has been established and the flanking markers are useful for the presymptomatic diagnosis of HYP. However, a recent study indicates locus heterogeneity and this may hinder the use of the flanking markers for presymptomatic diagnosis in additional families and in particular those from different populations. We have therefore investigated one Saudi-Arabian family (13 affected and six unaffected members) with hypophosphataemic rickets for linkage to these and other X-linked markers. A total of 17 cloned human X chromosome sequences identifying restriction fragment length polymorphisms were used to localize the mutant gene causing this disorder in the Saudi Arabian family. RESULTS: Nine (four from Xp and five from Xq) of the 17 X-linked DNA probes proved informative and linkage was established between HYP and the DSX41 locus, peak LOD score = 4.22 (recombination fraction, theta = 0.00). A positive peak LOD score of 2.32 (theta = 0.05) was also obtained between HYP and the DXS207 locus. Thus, the HYP gene in this Saudi Arabian family is linked to two of the four flanking markers which demonstrated linkage in families of Northern European origin. CONCLUSION: We conclude that the X-linked hypophosphataemic rickets gene in a Saudi Arabian family is located in the Xp22.3-p21.3, a region where this gene has previously been mapped by linkage studies of families of Northern European origin. Our studies have not demonstrated locus heterogeneity, so the flanking markers for HYP previously established in the families of Northern-European origin will be useful in the genetic counselling and presymptomatic diagnosis of this disorder in the Saudi Arabian family.

Adolescent↗

Do health visitors advise mothers about vitamin supplementation for their infants in line with government recommendations to help prevent rickets?

BACKGROUND: Increasing numbers of children are presenting with nutritional rickets. Rickets affects mainly dark-skinned infants being breastfed for prolonged periods without vitamin supplementation. The main aim of this study was to assess health visitors' (HV) knowledge of the government guidelines for vitamin supplementation for infants and children and the advice given to mothers. METHODS: Questionnaires were sent to all HV in Brent, Harrow and Westminster Primary Care Trusts (PCT). Information received was collated and used to assess HV knowledge. RESULTS: A total of 98 (69%) questionnaires were returned from HV. Seventy-nine HV (81%) recommend vitamins for the breastfed infant at 6 months or younger, 18 of which would recommend at 1 month of age. Fifty-six HV (57%) recommend vitamins until 5 years of age. Seventy-nine HV correctly identified Asians to be at risk of developing rickets. However, only 28 and 16 HV, respectively, identified Black Africans and Black Caribbeans to be at risk. CONCLUSION: Rickets has become a national public health issue. The majority of HVs is advising vitamin supplements according to government guidelines for breastfeeding infants and the age to which children should continue vitamin supplements. However, ethnic minority groups are at increased risk of vitamin D deficiency. Consequently, greater awareness needs to be raised about the government guidelines for vitamin D supplementation for ethnic minorities to ensure all HVs are imparting consistent, correct advice to these families.

Age Factors↗

Vitamin D-dependent rickets type I and type II.

Two distinct hereditary defects, vitamin D-dependent rickets type I (VDDR I) and type II (VDDR II), have been recognized in vitamin D metabolism. VDDR I is suggested to be a deficiency of the renal 25-hydroxyvitamin D (25(OH)D)-1 alpha-hydroxylase. Muscle weakness and rickets are the prominent clinical findings. A normal physiologic dose of 1 alpha-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 is sufficient to maintain remission of rickets in this disorder. VDDR II consists of a spectrum of intracellular vitamin D receptor (VDR) defects and is characterized by the early onset of severe rickets and associated alopecia. This can be attributed to mutations in the VDR gene. Massive doses of vitamin D analogs and calcium supplementation is usually required for the treatment; however, the response to therapy is sometimes variable.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗

Respiratory failure and multiple fractures in vitamin D-dependent rickets.

A 20-month-old boy presented with multiple fractures and respiratory failure. He was found to have vitamin D-dependent rickets. The rickets did not improve with phosphate, calcium and calciferol. The rickets healed, however, with large doses of 1-alpha-hydroxycholecalciferol. The presentation is unusual and the response to therapy suggests metabolic heterogeneity in vitamin D-dependent rickets.

Bone Resorption↗

Rickets in very low birthweight infants. Influence of supplementation with vitamin D, phosphorus and calcium.

The influence of extra phosphorus (P) and calcium (Ca) on the incidence of rickets was studied in 40 infants with a birthweight below 1.5 kg. All were fed breastmilk and all received vitamin D 1200 IU/day. Half of the infants were supplemented with P 20 mg/kg/day and Ca 30 mg/kg/day. Rickets, diagnosed with X-ray at 5 to 7 weeks of age, developed in 12 infants, 11 of whom weighed below 1.0 kg. In infants below 1.0 kg rickets was significantly more common in the group not receiving extra P and Ca. After diagnosis all were substituted and radiographic healing occurred in all. Serum Ca concentrations were normal in both groups whereas serum P was significantly lower in non-supplemented patients. Serum alkaline phosphatases (ALP) were normal in all patients at the time of diagnosis demonstrating the risk of using ALP as a diagnostic test for rickets in very low birthweight.

Alkaline Phosphatase↗

The parathyroid gland in metal rickets. A stereological study.

Rickets can be induced by oral administration of metals. A depressive effect exerted by metal ions on the parathyroid gland has previously been suggested to be a pathogenetic factor in strontium-induced rickets. In the present investigation, rickets was induced in young rats by oral administration of strontium and manganese, respectively. The parathyroids were fixed by perfusion and the total volume of the parathyroid glands was determined by serial sectioning. Conventional stereological techniques were applied on the ultrastructural level and the densities obtained could be related to the total mass of parathyroid tissue. In both rachitic groups the volume of the parathyroid glands as well as the absolute amounts of all cellular components studied, were reduced. All these changes were, however, correlated to the decreased body weight of the experimental animals. This is well in line with the finding of unaltered serum concentrations of calcium and immunoreactive parathyroid hormone. Therefore, it is concluded that the parathyroids do not play an important role in the pathogenesis of metal rickets.

Animals↗

A new kindred with hereditary hypophosphatemic rickets with hypercalciuria: implications for correct diagnosis and treatment.

Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a new autosomal form of hypophosphatemic rickets, recently described. This disease is characterized, and differs from other forms of hereditary hypophosphatemic rickets and/or osteomalacia by increased serum levels of 1,25-dihydroxyvitamin D, hypercalciuria and complete remission of the disease on phosphate therapy alone. However, only another probable Israeli kindred, and seemingly a few sporadic cases from Europe, North America and Japan have been reported in the literature. We describe here a new kindred of Jewish Yemenite origin (unrelated to other Israeli families) with typical HHRH. Two additional members of this family suffer from a milder asymptomatic form of the disease, which presents as absorptive hypercalciuria without signs or symptoms of bone disease. It seems to us that HHRH is underdiagnosed, due to its similarity to other hypophosphatemic syndromes in clinical, radiological and most biochemical parameters. Therefore, it is recommended that urinary calcium excretion and serum 1,25-dihydroxyvitamin D concentrations be measured in every patient with hypophosphatemic rickets/and or osteomalacia before the initiation of any therapy. The correct diagnosis of HHRN is of immense therapeutic implications. Phosphate therapy alone could cause a complete remission in HHRH, while the addition of active vitamin D metabolites, as is recommended in hypophosphatemic vitamin D resistant rickets, could cause deterioration in the patient's condition.

Adolescent↗