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PubMed1997

Hypophosphatemic vitamin D-resistant rickets, precocious puberty, and the epidermal nevus syndrome.

BACKGROUND: The association of multisystem pathologic conditions and epidermal nevi, known as the epidermal nevus syndrome, includes disorders of bone, central nervous system, eye, kidney, vasculature, body symmetry, and skin. Rarely, vitamin D-resistant rickets has been observed in association with this syndrome. Precocious puberty is another rare finding associated with epidermal nevus syndrome, having been observed in 3 patients. OBSERVATION: A female infant with an extensive epidermal nevus, hypophosphatemia, and precocious puberty is described. Despite medical therapy, the patient's phosphate levels continued to be very low (0.87-0.97 mmol/L), establishing the diagnosis of hypophosphatemic vitamin D-resistant rickets. At 21 months of age, areas of the nevus were excised. Laboratory values obtained shortly after the operation showed a significant, but transient, improvement in the serum phosphate level. After a second excision, maintenance of her serum phosphate level in the range of 1.29 to 1.61 mmol/L was possible. CONCLUSIONS: There is evidence that epidermal nevi produce a potent phosphaturic factor. We hypothesize that limited excision debulked the nevus sufficiently to allow medical management of the hypophosphatemia. Surgical intervention should be considered for patients affected with vitamin D-resistant rickets with epidermal nevi. The cause of the precocious puberty is unknown. It may be hypothesized that the nevus released a factor that induced puberty.

Abnormalities, Multiple↗

PubMed1987

Nutritional rickets in San Diego.

Despite the ability of infants to synthesize vitamin D through exposure to sunlight, nutritional rickets occasionally develops in infants even in areas with perennially sunny climates. In San Diego, a 1-year-old breast-fed infant presented with classic signs of nutritional rickets. Unsupplemented breast milk, limited exposure to sunlight, and darkly pigmented skin were predisposing factors. Because of this occurrence, we conducted a survey of vitamin supplementation practices among pediatricians in San Diego. Twenty-nine percent of 160 respondents do not prescribe vitamin D supplements for breast-fed infants. Those in practice less than ten years were even less likely to prescribe a vitamin supplement compared with their older colleagues. The patient report, coupled with a literature review, suggest the need for vitamin D supplementation for all nursing infants.

California↗

PubMed1991

Growth hormone therapy in hypophosphatemic rickets.

The effects of growth hormone therapy on the biochemical measures of bone metabolism were studied in 11 children aged 3.5 to 17 years who had familial hypophosphatemic rickets; five were male. Subjects were maintained on a regimen of stable doses of conventional therapy (calcitriol and phosphate). Subjects were studied at baseline receiving conventional therapy and during three sequential treatment periods: no therapy (4 weeks), growth hormone only (0.05 mg/kg per day for 4 weeks), and conventional therapy plus growth hormone (2 weeks). The nine youngest subjects were continued on a regimen of triple therapy for an additional 24 weeks. Serum phosphate averaged 0.93 +/- 0.13 mmol/L (mean +/- SD) at entry and decreased when the subjects were not receiving any therapy. During the 4 weeks of growth hormone only treatment, phosphate rose in all 11 subjects (0.70 +/- 0.08 mmol/L to 0.83 +/- 0.08 mmol/L). With triple therapy, phosphate remained higher than with no therapy. Calcitriol, osteocalcin, and parathyroid hormone increased as the subjects received growth hormone alone. Insulinlike growth factor I z scores rose significantly in response to growth hormone therapy alone. All nine subjects receiving 6 months of triple therapy increased their growth rate z scores. Exogenous growth hormone therapy may be useful in familial hypophosphatemic rickets.

Adolescent↗

PubMed1988

Sequential bone mineral content in small preterm infants with and without fractures and rickets.

Seventy-four infants with birth weights 1009 +/- 28 grams and gestational age 28.6 +/- 0.3 weeks (M +/- SEM) were studied prospectively to test the hypotheses that bone mineral content (BMC) measured by photon absorptiometry, would be: (1) lower in very low birth weight (VLBW) infants with radiographic evidence of fractures and/or rickets (F/R), and (2) will continue to be lower over the first year when compared to VLBW infants without F/R. BMC and bone width (BW) of the distal one-third of left radius and ulna were measured at 5 weeks (n = 8), 14 weeks (n = 61), 26 weeks (n = 58), 40 weeks (n = 59), and 1 year (n = 52). Standardized radiographs of both forearms, and weight, length, and head circumference were also determined at each study age. Investigators and technicians involved in the photon absorptiometry measurements were unaware of the radiographic findings and vice versa. Twenty-three of 74 infants were found to have F/R. BMC of studied infants remained markedly below our previously determined range of "intrauterine bone mineralization," even at 26 weeks after birth. There was no significant difference in BMC or BW between infants with and without F/R, either at the time of confirmation of F/R or during early follow-up; however, BMC was lower at greater than or equal to 6 months and BW was lower at greater than or equal to 9 months in infants with F/R. We suggest that the extremely low BMC measurements in early infancy predispose all VLBW infants to fractures and rickets.

Birth Weight↗

PubMed1994

Metabolic bone disease in black teenagers with genu valgum or varum without radiologic rickets: a bone histomorphometric study.

Calcium deficiency in black (African) children can cause rickets and osteomalacia with severe limb deformities. It is not known whether black teenagers with genu valgum or varum but without radiologic rickets suffer from a related disorder. To examine this question we studied 26 such patients by iliac crest bone biopsy and serum and urine biochemistry: 12 patients (46%) had osteopenia with normal or low bone turnover, 5 (19%) mildly increased bone turnover, 4 (15%) histologic hyperparathyroidism, 2 (8%) preosteomalacia, and 3 (12%) osteomalacia (with features of hyperparathyroidism). Radiographs did not reflect the severity of the bone disease. Serum calcium levels correlated inversely with eroded mineralized surface (p < 0.001), osteoid surface (p < 0.01), osteoid thickness (p < 0.001), mineralization lag time (p < 0.001), and 1,25-(OH)2 vitamin D (p < 0.005), and 1,25-(OH)2 vitamin D correlated positively with osteoid surface (p < 0.05), osteoid thickness (p < 0.05), osteoid volume (p < 0.01), eroded surface (p < 0.05), and eroded mineralized surface (p < 0.0005). Tubular reabsorption of phosphate and 25-OH vitamin D levels were normal, and 1,25-(OH)2 vitamin D levels were normal to high. This suggests that calcium deficiency may have caused the increase in bone turnover and the mineralization defects. The most severe osteomalacia was found in males aged 16-19 years. We cannot explain the cause of the osteopenia. We conclude that all patients had bone disease.

Adolescent↗

PubMed1987

A comparative study of the calcification-promoting action of 1,25 (OH)2D3 and calcitonin on the growth cartilage of rats with 1-hydroxyethylidene-1, 1-biphosphonic acid (HEBP)-induced rickets.

When HEBP (1-hydroxyethylidene-1, 1-biphosphonic acid) was administered to young rats in large doses over a short period rickets was consistently produced. When HEBP was administered concomitantly with 1,25 (OH)2D3 or calcitonin (CT), calcification appeared in the growth-plate cartilage where there had been an increase in thickness due to the inhibition of calcification. This experiment was done in an attempt to clarify differences in the calcification-promoting mechanisms of 1,25 (OH)2D3 and CT. The serum alkaline phosphatase level was reduced in rats with an accelerated calcification following the administration of 1,25 (OH)2D3, but there was no reduction in the serum alkaline phosphatase level in rats in which the calcification was accelerated by the administration of CT. The mode of appearance of calcification in the growth-plate cartilage by 1,25 (OH)2D3 or CT differed, depending on the time of administration. These results suggest that mechanisms involved in the enhancement of calcification by 1,25 (OH)2D3 and CT differ in cases where rickets are induced by HEBP.

Alkaline Phosphatase↗

PubMed1989

Promotion of calcification by imidazole and its suppression by diltiazem in the growth cartilage of rats with HEBP induced rickets.

The object of our experiments was to determine the effect of imidazole on the growth cartilage of rats with HEBP induced rickets. When HEBP (1-hydroxyethylidene-1, 1-bisphophonic acid) was given to young rats in large doses over a short period, rickets was consistently produced. We found that imidazole had a calcification promoting action in the growth plate cartilage where there had been an increase in thickness due to the inhibition of calcification. In an attempt to clarify the mechanism of accelerated calcification due to imidazole, the effects of diltiazem, a calcium antagonist, were observed; it was found to suppress the accelerated calcification. If diltiazem inhibits the entry of calcium ions into the cells of the growth cartilage, as it does in smooth muscle and myocardial cells, then our results indicate that intracellular concentrations of calcium may play an important role in the accelerated calcification due to imidazole.

Animals↗

PubMed1981

Spontaneous rickets in the wild arctic fox Alopex lagopus.

Normal and rachitic, skeletally immature arctic foxes (Alopex lagopus) were subjected to physical examination, roentgenographic studies, and in some cases histologic studies. The involved animals had active rickets coupled with antecedent normal diaphyseal bone formation. Evaluation of all the long bones showed highly variable manifestations of the disease, which undoubtedly reflect different rates of physeal endochondral transformation and metaphyseal remodeling. Histologic examination showed distinct patterns of widening of the physes and variable osteodystrophy in the trabecular and cortical bone of the metaphyses and epiphyseal ossification centers. These aforementioned factors certainly would necessitate different regional calcium needs and, therefore, different regional responses to the most rapid deficiency. The physes involved in the most rapid growth rates of this period showed the most widening of the growth plate, and the most dystrophic changes in the metaphysis. Skeletal injuries, including metaphyseal fractures and slow-down of longitudinal growth (particularly in the ulna) were also evident. Because of apparent dietary differences in the affected and normal fox kits, this juvenile-onset disease was presumed due to calcium-deficient intake following weaning. To the best of our knowledge this is the first report of spontaneously occurring rickets in a wild animal in its nautral habitat. There are several possible mechanisms for the variable widening of the physis and the loss of bone mineralization in these fox kits: calcium-deficient diet, binding of calcium in the bowel by high phosphorus intake, secondary hyperparathyroidism, and vitamin A toxicity.

Alaska↗

PubMed1985

Pseudotumor cerebri and nutritional rickets.

A bulging fontanelle due to benign increased intracranial pressure is not generally recognized as a manifestation of nutritional rickets but should be considered in the appropriate clinical setting. Two children who we saw presented with bulging anterior fontanelles were found to have pseudotumor cerebri in association with nutritional rickets.

Humans↗

PubMed1984

Activity of renal 25-hydroxyvitamin D3-1 alpha-hydroxylase in a case of X-linked hypophosphataemic rickets.

In 1974, a 2-year-old boy was diagnosed as having X-linked hypophosphataemic rickets (XLH) because of severe rickets and hypophosphataemia. The vitamin D metabolite concentrations, blood and urine chemistry and renal 25-hydroxyvitamin D3 (25OHD3)-1 alpha-hydroxylase were measured in 1982 (about 2 weeks after withdrawal of medication). 1 alpha-hydroxylase was 392 pg/mg tissue/20 min in the patient, which was high compared with aged-matched controls (69.7 +/- 28.5 pg/mg tissue/20 min, mean +/- SD, n = 7). Our present studies showed that the 1 alpha-hydroxylase activity in the patient with XLH was elevated. Therefore, the normal or low 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) concentrations in XLH patients could be due to accelerated catabolism of 1,25-(OH)2D3 or abnormally regulated 25OHD3-1 alpha-hydroxylase in response to hypophosphataemia, although significantly elevated above that in normal controls.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗

PubMed1989

Rickets due to dietary calcium deficiency.

Three children, aged 15-18 months were referred because of clinical, radiological and biochemical manifestations of rickets. Serum 25-hydroxycholecalciferol (25-OH-D3) values were within the normal range but 1,25-dihydroxychole-calciferol (1,25-diOH-D3) levels were markedly elevated. All signs and symptoms could be explained by dietary calcium deficiency. They all received the commercial Soya-drink - not adapted for infants - as their main source of nutrition for at least 6 months. Soya-drink has an extremely low calcium content. It should be remembered that defective calcium intake causes severe bone lesions and rickets in children in spite of adequate vitamin D supply.

Calcitriol↗

PubMed1984

Parathyroid function in different stages of vitamin D deficiency rickets.

Direct measurements of parathyroid activity are available in only small numbers of children with vitamin D deficiency rickets (VDR). Therefore serum immunoreactive parathyroid hormone (iPTH) and the urinary cyclic adenosine-3',5'-monophosphate excretion (UcAMP) were measured together with other important indices of calcium metabolism in 24 patients (aged 2-42 months) with VDR before vitamin D treatment. iPTH and UcAMP were significantly elevated in comparison to age-matched controls. In patients there was a highly significant positive correlation between iPTH and UcAMP and a negative relationship between both indices of parathyroid activity to serum phosphate and urine calcium, respectively, indicating that the simple measurement of serum phosphate and/or urine cAMP and Ca provides a reliable tool for the assessment of secondary hyperparathyroidism in VDR. In two patients classified as being in the early stage of VDR the parathyroid activity was not elevated despite hypocalcemia indicating relative hypoparathyroidism. Twelve patients with VDR were followed during vitamin D therapy: Within the first 2 weeks of treatment UcAMP slightly increased and thereafter decreased in most patients, but was still elevated in three patients even after 7 weeks, whereas iPTH became normal within 3 weeks of treatment. This favors the concept that vitamin D deficiency diminishes the activation of renal adenylate cyclase by PTH which is overcome by the highly increased PTH secretion in the advanced stages of rickets. The basal and calcium-stimulated serum calcitonin (CT) levels, determined in some of the patients, were normal, ruling out a significant disturbance of CT secretion in VDR.

Calcitonin↗

PubMed1981

Vitamin D dependent rickets: decreased sensitivity to 1,25-dihydroxyvitamin D.

A patient with vitamin D dependent rickets with decreased sensitivity to 1,25-Dihydroxyvitamin D was observed. She suffered from bone pain of two years duration beginning at 12 years of age and was found to be suffering from hypocalcemia, secondary hyperparathyroidism and osteomalacia. Laboratory findings revealed normal serum 25-hydroxyvitamin D (27 ng/ml) and markedly elevated serum 1,25-dihydroxy-vitamin D (131.9 pg/ml). The hypocalcemia was refractory in spite of administration of 25,000 units of vitamin D2, but therapy with high doses of oral la-hydroxyvitamin D3 resulted in significant elevation of the serum calcium level. The clinical findings and course of the patient's disease were quite different from those of other patients with vitamin D dependent rickets reported by other authors.

Adolescent↗

PubMed1975

The diagnosis of vitamin D deficiency rickets.

A clinical, radiological and biochemical study of 300 Cape coloured out-patients in order to clarify the diagnosis of rickets and to establish its incidence in the specific ethnic group selected, is presented. 95 Cases (31.6%) were diagnosed as suffering from rickets. Analysis of the results indicates that radiological examination is necessary to confirm or exclude the clinical diagnosis. The most useful biochemical parameter is the serum level of alkaline phosphatase.

Alkaline Phosphatase↗

PubMed1978

Influence of phenobarbital and diphenylhydantoin on the healing of rickets in the rat.

Male weanling Sprague-Dawley rats were administered phenobarbital or diphenylhydantoin (phenytoin, dilantin, DPH), or a combination of the two drugs, while receiving a high calcium, low phosphorus vitamin D-deficient diet. A Line Test evaluation for calcification of the distal end of the radius was performed to determine the presence of rickets and the healing of the disease. After a period of 16 days, rickets had developed in a uniform manner in all groups regardless of drug treatment. Four I.U. of vitamin D3 were then administered to each animal and they were sacrificed either 3 or 9 days later. Three days after the administration of D3, bone calcification had started in all groups, with the greatest response being observed in the control group. Nine days after D3 administration, bone calcification was clearly impaired in PB and PB-DPH treated animals and slightly impaired in the DPH treated group when compared to controls. Weight gain was also impaired after PB and combined PB-DPH treatments. Based on these observations, it is suggested that anticonvulsant drugs, and in particular PB, inhibit, in a yet undetermined fashion, the normal calcification of the growth cartilage which accompanies a single physiological dose of cholecalciferol in the rat.

Animals↗

PubMed1987

Radiological rickets in extremely low birthweight infants.

Forty-eight infants of birthweight less than 1000 g who survived for more than 28 days, had wrist X-rays to prospectively determine the incidence of radiological rickets. Twelve infants (25%) had normal X-rays throughout, 10 infants (21%) showed osteopenia and 26 infants (54%) had classical changes of rickets of which 8 (17% of the total) had spontaneous fractures. There was poor correlation between peak values of serum alkaline phosphatase and the radiological changes.

Alkaline Phosphatase↗

PubMed1989

Familial hypophosphatemic rickets: bone mass measurements in children following therapy with calcitriol and supplemental phosphate.

Familial hypophosphatemic rickets is characterized by defective skeletal mineralization resulting in abnormal growth and development. The pathologic and radiologic correlates of this syndrome have been given some investigation, but the effect of this mineralization defect on bone mineral density has not been adequately assessed. We measured axial and appendicular bone mineral in 17 children (mean age 5.59 +/- 4.87) with familial hypophosphatemia at baseline and at 6-month intervals after initiation of therapy with vitamin D3 (calcitriol) and phosphate supplementation. Noninvasive quantitative techniques included single photon absorptiometry (SPA) of the radius, combined cortical thickness (CCT) of the second metacarpal, and quantitative computed tomography (QCT) of vertebral trabecular bone. Thoraco-lumbar and hand/wrist radiographs were qualitatively assessed for the prevalence and severity of osteosclerosis, rickets, and other parameters indicative of metabolic bone disease as well as skeletal age. Quantitative determinations of bone mineral by each technique were compared with normal values for age and sex, and individual standardized scores (z-scores) were calculated at each measurement interval. Standard scores were also calculated for bone age-adjusted mineral values. At baseline, spinal trabecular bone by QCT was not significantly different from normal values; however, measurements of peripheral cortical bone by either SPA or CCT were significantly lower than values for normal children of the same age and sex (P = 0.05 and P = 0.01, respectively). Following therapy with calcitriol and phosphate, peripheral bone mass was not shown to improve significantly when contiguous standard scores were compared even when values were adjusted for bone age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1986

Absence of renal 25-hydroxycholecalciferol-1-hydroxylase activity in a pig strain with vitamin D-dependent rickets.

Cholecalciferol-1-hydroxylase activities were estimated in renal cortex homogenates and mitochondrial preparations from three groups of 6- to 12-week-old pigs. Five animals suffering from an inherited form of vitamin D-deficiency rickets showed symptoms of florid rickets when used for this study. Six pigs were normocalcemic heterozygous litter mates of the rachitic strain and three pigs were normal controls (German land-race and wild pigs). The renal cortex homogenates and mitochondrial preparations were incubated for 5-30 min at 37 degrees C with 25-(26-27-methyl-3H) OHD3 as substrate. 1,25(OH)2D3 was subsequently identified in normal phase (Zorbax-Sil) and reversed phase (Zorbax-ODS) HPLC eluates. 1-hydroxylase activities were demonstrated in both normal controls and heterozygote offspring and were ten times above minimum detectability of the assay. The km was 255 +/- 74 (SD) and 278 +/- 85 nmol X 1(-1) in controls and heterozygote offspring, respectively. The Vmax in the two groups was between 0.11 and 0.794 and decreased with age of the animals. Km and Vmax did not differ between the two groups. In homozygous, hypocalcemic rachitic animals no 1-hydroxylase activity was detectable in either homogenates or mitochondrial preparations. Addition of kidney homogenate from a rachitic animal to a homogenate from a normal pig did not specifically depress 1-hydroxylase activity in the mixture. Treatment of rachitic pigs with 1.0 microgram/day of 1,25(OH)2D3 for 4 weeks also had no effect on 1-hydroxylase activity. It is concluded that the rachitic pigs suffer from an inborn error of renal 1,25(OH)2D3 production.(ABSTRACT TRUNCATED AT 250 WORDS)

24,25-Dihydroxyvitamin D 3↗