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PubMed2006

Resurrection of vitamin D deficiency and rickets.

The epidemic scourge of rickets in the 19th century was caused by vitamin D deficiency due to inadequate sun exposure and resulted in growth retardation, muscle weakness, skeletal deformities, hypocalcemia, tetany, and seizures. The encouragement of sensible sun exposure and the fortification of milk with vitamin D resulted in almost complete eradication of the disease. Vitamin D (where D represents D2 or D3) is biologically inert and metabolized in the liver to 25-hydroxyvitamin D [25(OH)D], the major circulating form of vitamin D that is used to determine vitamin D status. 25(OH)D is activated in the kidneys to 1,25-dihydroxyvitamin D [1,25(OH)2D], which regulates calcium, phosphorus, and bone metabolism. Vitamin D deficiency has again become an epidemic in children, and rickets has become a global health issue. In addition to vitamin D deficiency, calcium deficiency and acquired and inherited disorders of vitamin D, calcium, and phosphorus metabolism cause rickets. This review summarizes the role of vitamin D in the prevention of rickets and its importance in the overall health and welfare of infants and children.

Calcium↗
PubMed1993

Role of plasma phosphate measurements in detecting rickets of prematurity and in monitoring treatment.

Twice weekly plasma and urine measurements were made in 24 very low birth weight infants. Intravenous feeding was given whilst infants required respiratory support. Subsequently they received breast milk or formula milk with a vitamin D supplement of 400 U/day. Fourteen babies required intravenous feeding for more than 10 days. Six developed radiological rickets or severe osteoporosis, and these infants had plasma phosphate levels < 1.2 mmol/L on breast milk or < 1.8 mmol/L on formula milk. Babies without radiological rickets had plasma phosphate levels > 1.2 mmol/L on breast milk and > 1.8 mmol/L in all but one on formula milk. Successful treatment of rickets was associated with a rise in plasma phosphate to the above levels. Untimed urine calcium and phosphate concentrations expressed as creatinine ratios were not helpful in detecting babies with rickets, but may be useful in monitoring therapy.

Alkaline Phosphatase↗
PubMedDate not supplied

Prophylaxis and treatment of childhood rickets with parenteral cholecalciferol.

The safety and efficacy of parenteral cholecalciferol was evaluated in the treatment and prevention of childhood rickets. Children with active disease, and those at high risk for developing rickets were treated either with intravenous or intramuscular cholecalciferol in dosages of 1000 to 1500 IU daily, for periods of 28 to 450 days. All children with rickets responded with radiographic evidence of healing. No child in the prophylaxis group developed bone disease. Side effects were minimal. Parenteral cholecalciferol is a safe and effective therapy for the treatment and prevention of childhood rickets.

Alkaline Phosphatase↗
PubMedDate not supplied

Myelofibrosis associated with severe vitamin D deficiency rickets.

Myelofibrosis is a rare disorder in childhood. In this report, we present the case of a 6-month-old infant with myelofibrosis due to severe vitamin D deficiency rickets. The characteristic clinical and laboratory findings of myelofibrosis improved rapidly after vitamin D therapy. In developing countries, nutritional rickets is still an important health problem. Rickets is not only a skeletal system-related disorder, it is also a systemic disorder. Rickets should be considered, therefore, as one of the conditions that can lead to severe haematological disorders in infants.

Bone and Bones↗
PubMed1975

1,25-dihydroxyvitamin D3 and 1, alpha-hydroxyvitamin D3 in children: biologic and therapeutic effects in nutritional rickets and different types of vitamin D resistance.

This investigation confirms the high level of biologic activity and the similarity of the effects of small doses of 1,25-dihydroxyvitamin D3 (1,25-(OH)2-D3) and of its analog 1alpha-hydroxyvitamin D3 (1alpha-OH-D3) on children with nutritional rickets, "pseudodeficiency" rickets (PDR), hereditary hypophosphatemia, chronic idiopathic hypoparathyroidism, and chronic renal failure. It also shows that cystinotic patients may develop, at the end stage of the disease, a certain degree of resistance to 1,25-(OH)2-D3. The comparison of the therapeutic effects of long term oral administration of 1,25-(OH)2-D3 or 1alpha-OH-D3 to two D-deficient children and two sibs with PDR demonstrates differences in sensitivity. In the patients with nutritional rickets, 0.5 mug/24 hr of either drug corrects the biochemical abnormalities, initiates healing of skeletal lesions in 28 days, and cures the metaphyseal le lesions in 60 days of therapy. In contrast, it appears that doses of either drug that are curative in D deficiency rickets are only partly active in PDR. These observations indicate that the hypothesis of a deficit in 25-hydroxycholecalciferol 1alpha-hydroxylase in patients with PDR must await for confirmation more direct evidences, and that such a deficit, even if proven, may not account for all of the biochemical and skeletal alterations seen in patients with this inherited disorder.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2002

Rickets in VDR null mice is secondary to decreased apoptosis of hypertrophic chondrocytes.

Both vitamin D deficiency and the absence of a functional vitamin D receptor (VDR) lead to a growth plate abnormality known as rickets. Prevention of abnormal mineral ion homeostasis by early institution of dietary therapy in VDR null mice prevents rickets, demonstrating that the VDR is not required for normal growth plate maturation. We, therefore, hypothesized that rickets, in the absence of a functional VDR, is due to impaired mineral ion homeostasis. Analyses of growth plate morphology in VDR null mice demonstrated normal resting and proliferating chondrocyte layers; however an expansion of the hypertrophic chondrocyte layer was present by 24 days of age. Because extracellular calcium has been shown to play a role in chondrocyte maturation, we addressed the hypothesis that hypocalcemia led to impaired chondrocyte differentiation. However, in situ hybridization analyses revealed normal expression of hypertrophic chondrocyte markers in the tibial growth plate of 24 day old VDR null mice, suggesting that the increase in the hypertrophic chondrocyte layer was not secondary to impaired differentiation. We then addressed whether expansion of the hypertrophic chondrocyte layer was secondary to increased proliferation or decreased apoptosis. BrdU labeling failed to demonstrate an increase in chondrocyte proliferation in the VDR null mice; however, apoptosis was markedly diminished in the late hypertrophic chondrocytes of the VDR null mice, suggesting that impairment in programmed cell death of these cells leads to the characteristic findings of rickets.

Animals↗
PubMed2001

Targeted inactivation of the 25-hydroxyvitamin D(3)-1(alpha)-hydroxylase gene (CYP27B1) creates an animal model of pseudovitamin D-deficiency rickets.

Pseudovitamin D-deficiency rickets is caused by mutations in the cytochrome P450 enzyme, 25-hydroxyvitamin D(3)-1alpha-hydroxylase (1alpha-OHase). Patients with the disease exhibit growth retardation, rickets, and osteomalacia. Serum biochemistry is characterized by hypocalcemia, secondary hyperparathyroidism, and undetectable levels of 1alpha,25-dihydroxyvitamin D(3). We have inactivated the 1alpha-OHase gene in mice after homologous recombination in embryonic stem cells. Serum analysis of homozygous mutant animals confirmed that they were hypocalcemic, hypophosphatemic, hyperparathyroidic, and that they had undetectable 1alpha,25-dihydroxyvitamin D(3). Histological analysis of the bones from 3-week-old mutant animals confirmed the evidence of rickets. At the age of 8 weeks, femurs from 1alpha-OHase-ablated mice present a severe disorganization in the architecture of the growth plate and marked osteomalacia. These results show that we have successfully inactivated the 1alpha-OHase gene in mice and established a valid animal model of pseudovitamin D-deficiency rickets.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1977

Hypercalcemic hyperparathyroidism in hypophosphatemic rickets.

A 25-year-old white woman with sporadic hypophosphatemic rickets presented with a 7 year history of chronic mild hypercalcemia, osteitis fibrosa cystic and hypercalcemic nephropathy. Serum immunoreactive parathyroid hormone was elevated by greater than 100-fold and a 3.5 g parathyroid tumor was found at operation. Survey of the literature reveals that of 9 previous cases in which hypercalcemic hyperparathyroidism occurred in association with hypophosphatemic rickets, only two had classical x-linked familial hypophosphatemic rickets. It appears more than likely that this unusual combination of skeletal diseases represents the chance occurrence of primary hyperparathyroidism in patients with underlying x-linked familial hypophosphatemic rickets rather than a complication of phosphate therapy.

Adolescent↗
PubMed1985

The concurrence of hypoparathyroidism provides new insights to the pathophysiology of X-linked hypophosphatemic rickets.

Controversy exists over the role that PTH and extracellular fluid calcium concentration may play in modulation of the renal phosphate transport defect in X-linked hypophosphatemic rickets. In previous studies, administration of PTH to affected subjects resulted in an increase or no effect on renal phosphate excretion, while calcium infusion increased renal tubular phosphate transport. In contrast, patients with X-linked hypophosphatemic rickets and hyperparathyroidism have no change in their renal phosphate wasting after parathyroidectomy. However, none of these were permanently hypoparathyroid postoperatively. We describe a patient with idiopathic hypoparathyroidism in whom we proved the coexistence of X-linked hypophosphatemic rickets using family history and dental abnormalities. Initially, the patient had a mean serum calcium level of 5.6 +/- 0.07 (+/- SE) mg/dl and a renal tubular maximum for reabsorption of phosphate per liter glomerular filtrate (TmP/GFR) of 6.5 +/- 0.46 mg/dl. Hypoparathyroidism was confirmed, and therapy with vitamin D (50,000 U/day) and calcium (1,000 mg/day) was begun. On this regimen, serum calcium rose to 8.1 +/- 0.2 mg/dl, and TmP/GFR declined to 2.59 +/- 0.12 mg/dl. Bone biopsy revealed the persistence of osteomalacia. Subsequently, therapy with 1,25-dihydroxyvitamin D3 (1.0 microgram/day) was initiated, and serum calcium rose to 9.6 +/- 0.07 mg/dl, and TmP/GFR declined to 1.79 +/- 0.16 mg/dl. The prevailing serum calcium level correlated inversely with the TmP/GFR (r2 = 0.91; P less than 0.001). These data indicate that calcium and/or PTH are involved in modulation of the renal phosphate transport defect in X-linked hypophosphatemic rickets.

Adult↗
PubMed1998

A PHEX gene mutation is responsible for adult-onset vitamin D-resistant hypophosphatemic osteomalacia: evidence that the disorder is not a distinct entity from X-linked hypophosphatemic rickets.

Previous investigators described a kindred with an X-linked dominant form of phosphate wasting in which affected children did not have radiographic evidence of rickets, whereas older individuals were progressively disabled by severe bowing. They proposed that this kindred suffered from a distinct disorder that they referred to as adult-onset vitamin D-resistant hypophosphatemic osteomalacia (AVDRR). We recently identified a gene, PHEX, that is responsible for the disorder X-linked hypophosphatemic rickets. To determine whether AVDRR is a distinct form of phosphate wasting, we searched for PHEX mutations in affected members of the original AVDRR kindred. We found that affected individuals have a missense mutation in PHEX exon 16 that results in an amino acid change from leucine to proline in residue 555. Clinical evaluation of individuals from this family indicates that some of these individuals display classic features of X-linked hypophosphatemic rickets, and we were unable to verify progressive bowing in adults. In light of the variability in the clinical spectrum of X-linked hypophosphatemic rickets and the presence of a PHEX mutation in affected members of this kindred, we conclude that there is only one form of X-linked dominant phosphate wasting.

Adolescent↗
PubMed2004

Secondary prevention of vitamin D-deficiency rickets.

Reports of vitamin D-deficiency rickets and its associated morbidity continue among inadequately supplemented, dark-skinned breastfed infants. Despite the new vitamin D dietary guidelines, there remain significant numbers of unsupplemented breastfed infants. Here we report a case of subclinical vitamin D-deficiency rickets. This patient had biochemical and radiographic but not clinical evidence for rickets. We propose a new step of screening high-risk infants for subclinical rickets using wrist films paired with 25-hydroxyvitamin D levels.

Alkaline Phosphatase↗
PubMedDate not supplied

Hypoglycemia spiking mortality syndrome in broilers with rickets and a subsequent investigation of feed restriction as a contributing factor.

Several cases of elevated mortality with neurologic signs in 14-to-16-day-old broilers were presented to the Poultry Diagnostic and Research Center from one local integrated company. Suspected of "spiking mortality" associated with hypoglycemia, blood glucose levels were <150 mg/dl overall, with several birds with blood glucose levels as low as 30 mg/dl. Tissues, submitted for histopathology, revealed rickets in 50% of the birds. Virus isolation and serology for reovirus and infectious bursal disease virus were negative. After evaluation of these cases, a brief investigation was conducted to determine the effects of feed restriction on the induction of rickets and resulting hypoglycemia. One-hundred 1-day-old broilers were randomly assigned to three treatment groups of: 1) ad libitum feed, 2) 25% restriction, and 3) 50% restriction. Restriction began on the fifth day of age and continued to 21 days of age. Samples collected during the course of the study included whole blood for blood glucose measurements and proximal tibiotarsus for histopathologic examination for rickets. We were unable to reproduce the clinical signs of spiking mortality, neurologic changes, or hypoglycemia experimentally. Histopathology of the growth plates of the proximal tibiotarsus did indicate mild changes consistent with rickets, but the changes were not significant between treatment groups.

Animal Feed↗
PubMed2000

Management and prevention of vitamin D deficiency rickets in captive-born juvenile chimpanzees (Pan troglodytes).

Vitamin D deficiency rickets was diagnosed in three juvenile chimpanzees (Pan troglodytes) raised indoors under skylights and consuming only breast milk. Two cases detected early had mild but characteristic radiographic changes. More advanced disease presented with florid x-ray features of rickets and pathologic fractures, as well as hypocalcemia, hypophosphatemia, and low serum 25-hydroxyvitamin D levels. Treatment by a single injection of vitamin D2 in sesame oil (slow release) followed by daily oral supplementation with vitamin D2 corrected the condition. On the basis of experience with these cases and comparison with rickets in humans, a prevention protocol for mother-reared, inside-housed, chimpanzee juveniles was developed. Injection with slow release vitamin D2 (5,000 IU i.m. once) at 4 mo of age, followed by oral supplementation of 400 IU vitamin D2 daily until weaning, prevents rickets in juvenile chimpanzees raised indoors.

Administration, Oral↗
PubMed1983

Dietary level of fat, calcium, and vitamins A and D3 as contributory factors to rickets in poults.

Two experiments were conducted on dietary predisposition to rickets in poults. The first experiment compared fat type (corn oil or tallow), level of added fat (3.5 or 7%), vitamin D3 (900 or 2,400 IU/kg feed), and total calcium (.6, 1.2, or 3%) inclusion in the diet. Poults fed diets supplemented with corn oil had higher percentage tibia ash than poults fed tallow-supplemented diets. Vitamin D3 included at 2,400 IU/kg feed increased body weights significantly by 2 and 4 weeks of age and lowered plasma alkaline phosphatase (AP) at 2 and 4 weeks compared with diets containing 900 IU/kg feed. Tibia ash was significantly greater with the higher vitamin D3 supplementation at 2 weeks. At 2 weeks of age both low (.6%) and high (3%) levels of dietary calcium increased plasma AP, decreased tibia ash, and decreased body weight compared with diets containing 1.2% calcium. By 4 weeks of age, diets containing 1.2 and 3% calcium had no significant effects on body weight and plasma AP; however, tibia ash was significantly greater with these levels than with the .6% calcium diets. The second experiment compared level of dietary tallow inclusion (2.5 or 7%) and supplementary vitamin A (4,000, 16,000, or 44,000 IU/kg feed). The high tallow diets decreased tibia ash at 3 weeks, and the maximum supplementation of vitamin A significantly depressed body weight. Clinical rickets were first noted at 18 days of age. By 26 days of age the higher level of dietary fat and the highest level of vitamin A caused a significant increase in severity of rickets. The results suggested that rickets can be induced by high dietary levels of tallow and vitamin A.

Alkaline Phosphatase↗
PubMed1999

Incidence of rickets of prematurity at Kenyatta National Hospital, Nairobi.

BACKGROUND: Reports of osteopaenia/rickets of prematurity are on the increase due to improved survival rates of low birthweight infants. OBJECTIVE: To establish the incidence of rickets of prematurity by the age of six months in premature infants born at Kenyatta National Hospital, Nairobi. DESIGN: Prospective cohort study. SETTING: Newborn unit and paediatric outpatient follow up clinic of Kenyatta National Hospital. SUBJECTS: Successive surviving infants of birthweight less than 2000 g residents in Nairobi. RESULTS: Incidence of rickets of prematurity by six months of age was 58.8%. Rickets appeared more commonly in male infants compared to female infants. CONCLUSION: Rickets of prematurity is a common problem in the premature infants seen at Kenyatta National Hospital. Routine vitamin D supplements to premature infants in adequate doses of at least 400iu per day should be adopted in our centre.

Female↗
PubMed2000

Nutritional rickets: report of four cases diagnosed at orthopaedic evaluation.

Nutritional rickets, the classic form of vitamin D-deficiency rickets, is rarely seen in the setting of modern medicine. We report four cases of nutritional rickets diagnosed at the time of orthopedic evaluation at our institutions during a 3-year period. All patients were referred by their pediatricians for evaluation of bowlegs. All children lived in a northern climate. Three were black and one was white. Prolonged breast-feeding and an unusual diet were identified as the underlying cause in our cases. Genu varum, seen in the setting of relative short stature and low weight, with a consistent social history, should raise the suspicion for nutritional rickets. The continued prevalence of this disease entity must be recognized in both the primary care and the orthopedic surgery setting. Vitamin D supplementation and enhanced sunlight exposure serve as effective prophylaxis and treatment of this disease.

Child, Preschool↗
PubMedDate not supplied

Carnitinuria in rickets due to vitamin D deficiency.

In this study, we measured the serum-urine total carnitine levels and PTH levels before and after treatment in 18 patients with nutritional rickets. The urine and blood samples were taken on the first (pretreatment) and the 15th day of the study (post-treatment). The total carnitine levels of serum and urine samples, serum PTH and serum-urine creatinine concentrations were determined. We found that the levels of carnitine excreted in the urine on the first (pre-treatment) and on the 15th day (post-treatment) were higher than the reference levels. Decrease in carnitine excretion on the 15th day seemed to be correlated with decrease in aminoaciduria at that time. The study showed a significant correlation between urinary carnitine excretion and serum PTH levels. In our study we did not find any significant difference between the serum total carnitine levels on the first (pre-treatment) and the 15th day (post-treatment), and both values were lower than the reference values for the same age group. We observed that the total serum carnitine levels did not change on the 15th day of the post-treatment period in spite of a decrease in urinary carnitine excretion. The results of the present study indicated that carnitine metabolism is disturbed in nutritional rickets. Further evaluation of rickets cases and new studies will probably lead to a better understanding of carnitine metabolism in nutritional rickets.

Amino Acids↗
PubMedDate not supplied

[Rickets prophylaxis under current recommendations].

AIM OF THE STUDY: We analysed the compliance of current recommendations concerning rickets prevention in Poland. MATERIAL AND METHODS: The study group consisted of 65 infants hospitalised because of emergency problems. In each case, the medical history included prophylaxis of rickets and feeding pattern. In most cases (80%) we measured calcium, phosphate, and alkaline phosphatase in the serum. RESULTS: Vitamin D3 was overdosed in 70% of infants. 14% of children were diagnosed as rachitic in outpatient department before hospitalisation, but neither the clinical symptoms nor the laboratory test confirmed the diagnosis. This confirms the observation, that rickets is diagnosed too often, usually on the basis of isolated craniotabes in young infants. CONCLUSION: In the context of changing recommendations for prophylaxis of rickets, we recommend more careful prescribing of vitamin D3 preparations.

Drug Overdose↗