Incidence and prevalence of nutritional and hereditary rickets in southern Denmark

OBJECTIVE

To estimate the incidence of nutritional rickets and the incidence and prevalence of hereditary rickets.

DESIGN

Population-based retrospective cohort study based on a review of medical records.

METHODS

Patients aged 0-14.9 years referred to or discharged from hospitals in southern Denmark from 1985 to 2005 with a diagnosis of rickets were identified by register search, and their medical records were retrieved. Patients fulfilling the diagnostic criteria of primary rickets were included.

RESULTS

We identified 112 patients with nutritional rickets of whom 74% were immigrants. From 1995 to 2005, the average incidence of nutritional rickets in children aged 0-14.9 and 0-2.9 years was 2.9 and 5.8 per 100,000 per year respectively. Among immigrant children born in Denmark, the average incidence was 60 (0-14.9 years) per 100,000 per year. Ethnic Danish children were only diagnosed in early childhood and the average incidence in the age group 0-2.9 years declined from 5.0 to 2.0 per 100,000 per year during 1985-1994 to 1995-2005. Sixteen cases of hereditary rickets were diagnosed during the study period giving an average incidence of 4.3 per 100,000 (0-0.9 years) per year. The prevalence of hypophosphatemic rickets and vitamin D-dependent rickets type 1 was 4.8 and 0.4 per 100,000 (0-14.9 years) respectively.

CONCLUSIONS

Nutritional rickets is rare in southern Denmark and largely restricted to immigrants, but the incidence among ethnic Danish children was unexpectedly high. Hereditary rickets is the most common cause of rickets in ethnic Danish children, but nutritional rickets is most frequent among all young children.

FGF23 and its role in X-linked hypophosphatemia-related morbidity

Background

X-linked hypophosphatemia (XLH) is an inherited disease of phosphate metabolism in which inactivating mutations of the Phosphate Regulating Endopeptidase Homolog, X-Linked (PHEX) gene lead to local and systemic effects including impaired growth, rickets, osteomalacia, bone abnormalities, bone pain, spontaneous dental abscesses, hearing difficulties, enthesopathy, osteoarthritis, and muscular dysfunction. Patients with XLH present with elevated levels of fibroblast growth factor 23 (FGF23), which is thought to mediate many of the aforementioned manifestations of the disease. Elevated FGF23 has also been observed in many other diseases of hypophosphatemia, and a range of animal models have been developed to study these diseases, yet the role of FGF23 in the pathophysiology of XLH is incompletely understood.

Methods

The role of FGF23 in the pathophysiology of XLH is here reviewed by describing what is known about phenotypes associated with various PHEX mutations, animal models of XLH, and non-nutritional diseases of hypophosphatemia, and by presenting molecular pathways that have been proposed to contribute to manifestations of XLH.

Results

The pathophysiology of XLH is complex, involving a range of molecular pathways that variously contribute to different manifestations of the disease. Hypophosphatemia due to elevated FGF23 is the most obvious contributor, however localised fluctuations in tissue non-specific alkaline phosphatase (TNAP), pyrophosphate, calcitriol and direct effects of FGF23 have been observed to be associated with certain manifestations.

Conclusions

By describing what is known about these pathways, this review highlights key areas for future research that would contribute to the understanding and clinical treatment of non-nutritional diseases of hypophosphatemia, particularly XLH.

The impact of vitamin D on fetal and neonatal lung maturation. A systematic review

Respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) are major complications to preterm birth. Hypovitaminosis D is prevalent in pregnancy. We systematically reviewed the evidence of the impact of vitamin D on lung development, surfactant synthesis, RDS, and BPD searching PubMed, Embase, and Cochrane databases with the terms vitamin D AND (surfactant OR lung maturation OR lung development OR respiratory distress syndrome OR fetal lung OR prematurity OR bronchopulmonary dysplasia). Three human studies, ten animal studies, two laboratory studies, and one combined animal and laboratory study were included. Human evidence was sparse, allowing no conclusions. BPD was not associated with vitamin D receptor polymorphism in a fully adjusted analysis. Animal and laboratory studies showed substantial positive effects of vitamin D on the alveolar type II cell, fibroblast proliferation, surfactant synthesis, and alveolarization. These data support the hypothesis of hypovitaminosis D as a frequent, modifiable risk factor of RDS and BPD, which should be tested in randomized controlled trials on pregnant women, those with threatening preterm delivery, or in the preterm neonates. Future experimental and human studies should aim to identify optimal time windows, vitamin D doses, and cut-off levels for 25-hydroxyvitamin D in interventions against RDS, BPD, and later adverse respiratory outcomes.

Prevalence of maternal chronic diseases during pregnancy - a nationwide population based study from 1989 to 2013

INTRODUCTION

There is substantial evidence of a negative impact of maternal chronic disease during pregnancy on reproductive outcomes. Knowledge of the prevalence of chronic diseases during pregnancy is limited, but essential for a focused preventive effort regarding optimal disease control during pregnancy. We aimed to analyze the prevalence of chronic diseases during pregnancy.

MATERIAL AND METHODS

This register-based cohort study included all women giving birth in Denmark between 1989 and 2013 based on data from Danish health registers. Maternal chronic diseases included 23 disease categories of both physical and mental health conditions recorded within a period of 10 years before childbirth.

RESULTS

We included 1 362 200 childbirths during the study period. The overall prevalence of maternal chronic disease increased from 3.71% in 1989 to 15.76% in 2013. The most frequently registered chronic diseases were chronic lung diseases/asthma (1.73%), thyroid disorders (1.50%) and anxiety and personality disorders (1.33%). Taking increasing maternal age at birth into account, the relative risk for women to have a chronic disease from 2009 to 2013 was 4.14 (95% CI 4.05-4.22), compared with mothers giving birth from 1989 to 1993.

CONCLUSIONS

We found an increasing prevalence of maternal chronic disease during pregnancy and more than a four-fold increased risk of maternal chronic disease during pregnancy for childbirths in the period 2009 through 2013, compared with 1989 through 1993. The main limitation of our study is related to a potentially greater awareness and hence more careful registration of maternal chronic disease over time and thereby an increased tendency to register diseases.

Parity and tanned white skin as novel predictors of vitamin D status in early pregnancy: a population-based cohort study

CONTEXT

In pregnancy, vitamin D insufficiency and deficiency, defined as serum 25-hydroxyvitamin D (25(OH)D) <50 nM, and <25 nM, respectively, may have adverse effects for both mother and child. Prevalence estimates, and identification of subgroups at special risk, may be useful for the planning of preventive strategies.

OBJECTIVE

To study the prevalence and risk factors of hypovitaminosis D in early pregnancy.

DESIGN AND METHODS

In a cross-sectional study of 1348 women in early pregnancy from the Odense Child Cohort, Denmark, 25(OH)D was determined and correlated to demographic and lifestyle variables (age, nationality, skin tone, parity, prepregnancy body mass index (BMI), smoking and sun exposure), using multiple linear and logistic regression analyses for all year, or stratified for summer and winter. The risk of vitamin D insufficiency was expressed as odds ratios (OR) with 95% confidence intervals in brackets.

RESULTS

The prevalence of vitamin D insufficiency and deficiency was estimated to 27·8% and 3·5% respectively. In adjusted analyses, vitamin D insufficiency was directly associated with winter season, OR = 1·89 (1·35-2·63); increasing prepregnancy BMI, OR = 1·06 (1·03-1·10); and smoking, OR = 2·7 (1·34-5·41); but was less frequent in nulliparous, OR = 0·47 (0·33-0·68) and tanned Caucasians, OR = 0·63 (0·41-0·97). Season-specific associations having parental origin from outside Europe in summer, OR = 4·13 (1·41-12·13); in winter smoking, OR = 3·15 (1·19-8·36); and prepregnancy BMI, OR = 1·12 (1·06-1·18).

CONCLUSIONS

Vitamin D insufficiency was widespread in early pregnancy. Associations to smoking, prepregnancy BMI and origin outside Europe varied with season. Multiparity and not being tanned in Caucasians represent new risk factors of vitamin D insufficiency.

Nutritional rickets in Denmark: a retrospective review of children's medical records from 1985 to 2005

INTRODUCTION

This study describes clinical and biochemical characteristics of nutritional rickets and risk factors at diagnosis among children living in Denmark. All medical records from patients with rickets referred to or discharged from hospitals in Southern Denmark from 1985 to 2005 were identified by register search.

MATERIALS AND METHODS

Patients included were younger than 15 years of age and fulfilled the diagnostic criteria of primary, nutritional rickets. A total of 112 patients with nutritional rickets were included: 29 were of ethnic Danish origin, and 83 were immigrants.

RESULTS

Patients diagnosed before the age of 4 (median 1.4) years displayed the classic clinical signs of rickets, whereas patients diagnosed after the age of 4 (median 12.5) years had few clinical signs and unspecific symptoms. Ethnic Danish patients were only diagnosed before age 24 months, and they accounted for 73% of all cases presenting with hypocalcemic seizures, but biochemically, they did not have more severe rickets. Of patients diagnosed before the age of 4 years, 45% were ethnic Danish. In early childhood, insufficient or no vitamin D supplementation was given in 88% of all cases. Among immigrant girls older than 4 years of age, 78% were veiled.

DISCUSSION

Nutritional rickets in Denmark is predominantly a disease among immigrants, but ethnic Danish patients comprised nearly half of all patients diagnosed before the age of 4 years, and they presented more frequently with hypocalcemic seizures. The main risk factors were omitted, such as vitamin D prophylaxis among the youngest patients and veiling among older children/teenagers.

Bone geometry, volumetric density, microarchitecture, and estimated bone strength assessed by HR-pQCT in adult patients with hypophosphatemic rickets

Hypophosphatemic rickets (HR) is characterized by a generalized mineralization defect. Although densitometric studies have found the patients to have an elevated bone mineral density (BMD), data on bone geometry and microstructure are scarce. The aim of this cross-sectional in vivo study was to assess bone geometry, volumetric BMD (vBMD), microarchitecture, and estimated bone strength in adult patients with HR using high-resolution peripheral quantitative computed tomography (HR-pQCT). Twenty-nine patients (aged 19 to 79 years; 21 female, 8 male patients), 26 of whom had genetically proven X-linked HR, were matched with respect to age and sex with 29 healthy subjects. Eleven patients were currently receiving therapy with calcitriol and phosphate for a median duration of 29.1 years (12.0 to 43.0 years). Because of the disproportionate short stature in HR, the region of interest in HR-pQCT images at the distal radius and tibia were placed in a constant proportion to the entire length of the bone in both patients and healthy volunteers. In age- and weight-adjusted models, HR patients had significantly higher total bone cross-sectional areas (radius 36%, tibia 20%; both p < 0.001) with significantly higher trabecular bone areas (radius 49%, tibia 14%; both p < 0.001) compared with controls. In addition, HR patients had lower total vBMD (radius -20%, tibia -14%; both p < 0.01), cortical vBMD (radius -5%, p < 0.001), trabecular number (radius -13%, tibia -14%; both p < 0.01), and cortical thickness (radius -19%; p < 0.01) compared with controls, whereas trabecular spacing (radius 18%, tibia 23%; p < 0.01) and trabecular network inhomogeneity (radius 29%, tibia 40%; both p < 0.01) were higher. Estimated bone strength was similar between the groups. In conclusion, in patients with HR, the negative impact of lower vBMD and trabecular number on bone strength seems to be compensated by an increase in bone diameter, resulting in HR patients having normal estimates of bone strength. © 2014 American Society for Bone and Mineral Research.

Periapical and endodontic status of permanent teeth in patients with hypophosphatemic rickets

Hypophosphatemic rickets (HR) is a rare hereditary disease in which dental problems in terms of spontaneous periapical infections are frequently reported. Most previous reports have been based on a small number of HR patients and have been published before the disease could be confirmed genetically. The aim of the present study was to describe the periapical and endodontic status of permanent teeth in patients with genetically and/or biochemically confirmed HR. The patients were recruited from a medical study on HR patients. The patients underwent a dental examination including a digital panoramic radiograph, which was scored for endodontically affected teeth (i.e. teeth with periapical radiolucencies and/or endodontically treated teeth). A total of 52 patients (age range: 5·7-74·5 years; 17 males and 35 females) were included. HR patients were characterised by a high number of endodontically affected teeth (mean: 4·2; s.d.: 5·0). The number of affected teeth rose significantly with age (P < 0·01), and no statistically significant gender difference was found. The relative distribution of endodontically affected teeth in the three tooth groups (incisors and canines, premolars, and molars) varied according to age. In the youngest age group, only incisors and canines were affected, while the relative proportion of affected premolars and molars increased with age. Endodontically affected teeth are common in HR patients, and the number of affected teeth increased significantly with age. Hence, the need for endodontic treatment among HR patients is comprehensive.

High bone mineral apparent density in children with X-linked hypophosphatemia

Bone mineral apparent density (BMAD) in children with X-linked hypophosphatemia (XLH) was evaluated, as they are unlikely to have extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients. Children with XLH also had significantly higher BMAD of the spine compared to femoral neck.

INTRODUCTION

BMAD obtained by dual-energy X-ray absorptiometry scans in children with XLH was evaluated, as they are unlikely to have the extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients.

METHODS

A total of 15 children with biochemically and genetically verified XLH were recruited. Anthropometric measurements were performed, and to correct for the short stature (small bones), the BMAD of the spine and the femoral neck was evaluated.

RESULTS

Z-scores of BMAD of the spine (mean (95 % CI); 2.0 (1.3-2.7); p < 0.001) were significantly elevated compared to reference children. Z-scores of the femoral neck (1.0 (-0.0 to 2.1); p = 0.059) tended to be elevated. Spine Z-scores were significantly higher than the Z-scores of the femoral neck, (paired t test, p = 0.02). BMAD of the spine was evaluated according to the Molgaard's approach; XLH children had normal bone size of the spine for age due to a normal sitting height Z-score of -0.4 (-1.0 to 0.1); p = 0.1. Z-scores of bone mineral content (BMC) of the spine for bone area were elevated (1.4 (0.8-2.1); p < 0.001). No reference data were available to allow evaluation of the BMAD of the femoral neck by the Molgaard's approach.

CONCLUSIONS

Children with XLH have an increased BMAD and a high BMC for bone area at the lumbar spine, and this was due to causes other than extra-skeletal ossifications and corrected for bone size. The BMAD of the spine was significantly higher compared to the femoral neck.

Oral health-related quality of life in X-linked hypophosphataemia and osteogenesis imperfecta

X‐linked hypophosphataemia (XLH) and osteogenesis imperfecta (OI) are rare congenital disorders characterised by skeletal dysplasia. The two disorders may include dental anomalies potentially affecting individual well‐being. The aims of study were (a) to assess the oral health‐related quality of life (OHRQoL) in Danish adults with XLH or OI, and (b) to compare the results of the groups. A cross‐sectional study including 35 adults with XLH, 56 adults with OI type I and 17 adults with OI types III‐IV was conducted. The OHRQoL was assessed by the 49‐item version of the questionnaire Oral Health Impact Profile (OHIP). Summed domain scores (seven) were compared between XLH and OI groups. Prevalence of severe impact on OHRQoL (scores 3‐4) was compared between groups. The median scores in XLH group exceeded the medians in OI (P < .05) in the domains functional limitation (XLH:6.5; OI:4.0), pain (XLH:9.5; OI:5.0), psychological discomfort (XLH:5.5; OI:2.0), psychological disability (XLH:2.0; OI:0.0), handicap (XLH:2.0; OI:0.0) and total OHIP (XLH:35.0; OI:14.0). Differences in domains physical disability (XLH: 4.0; OI: 1.0) and social disability (XLH: 0.0; OI: 0.0) were not significant. Prevalence of severe impact on OHRQoL in the XLH group significantly exceeded the level in OI group in the domains functional limitation (XLH: 59%; OI: 35%), psychological discomfort (XLH: 38%; OI: 20%) and physical disability (XLH: 32%; OI: 13%). In conclusion, adults with XLH experience a higher negative impact on their OHRQoL than adults with OI. Only to a minor degree, individuals with OI types III‐IV experience a higher impact on OHRQoL than individuals with OI type I.

Vitamin D Depletion in Pregnancy Decreases Survival Time, Oxygen Saturation, Lung Weight and Body Weight in Preterm Rat Offspring

Animal studies suggest a role of vitamin D in fetal lung development although not studied in preterm animals. We tested the hypothesis that vitamin D depletion aggravates respiratory insufficiency in preterm rat offspring. Furthermore, the effects of vitamin D depletion on growth and lung surfactant were investigated. Female Sprague-Dawley rats were randomly assigned low vitamin D (VD_L) or control diet before mating and followed with serum 25-hydroxyvitamin D (s-25(OH)D) determinations. After cesarean section at gestational day 19 (E19) or day 22 (E22), placental weight, birth weight, crown-rump-length (CRL), oxygenation (SaO₂) at 30 min and survival time were recorded. The pup lungs were analyzed for phospholipid levels, surfactant protein A-D mRNA and the expression of the vitamin D receptor (VDR). S-25(OH)D was significantly lower in the VD_L group at cesarean section (12 vs. 30nmol/L, p<0.0001). Compared to the controls, E19 VD_L pups had lower birth weight (2.13 vs. 2.29g, p<0.001), lung weight (0.09 vs. 0.10g, p = 0.002), SaO₂(54% vs. 69%, p = 0.002) as well as reduced survival time (0.50 vs. 1.25h, p<0.0001). At E22, the VD_L-induced pulmonary differences were leveled out, but VD_L pups had lower CRL (4.0 vs. 4.5cm, p<0.0001). The phospholipid levels and the surfactant protein mRNA expression did not differ between the dietary groups. In conclusion, Vitamin D depletion led to lower oxygenation and reduced survival time in the preterm offspring, associated with reduced lung weight and birth weight. Further studies of vitamin D depletion in respiratory insufficiency in preterm neonates are warranted.

Elevated Bone Remodeling Markers of CTX and P1NP in Addition to Sclerostin in Patients with X-linked Hypophosphatemia: A Cross-Sectional Controlled Study

Aspects of bone remodeling have only been scarcely studied in X-linked hypophosphatemia (XLH). In this cross-sectional controlled study, we assessed biochemical indices of bone remodeling and sclerostin in 27 adult patients (median age 47 [range 24-79] years, 19 women, 8 men) with XLH matched with 81 healthy control subjects (1:3) with respect to age-, sex-, and menopausal status. Markers of bone resorption (carboxyterminal cross-linked telopeptide of type 1 collagen, CTX) and formation (N-terminal propeptide of type 1 procollagen, P1NP) were higher in XLH patients compared to controls (median [IQR] 810 [500-1340] vs 485 [265-715] ng/l and 90 [57-136] vs 49 [39-65] ug/l, respectively, both p < 0.001) as well as sclerostin (0.81 [0.60-1.18] vs 0.54 [0.45-0.69] ng/ml, p < 0.001). Similar differences were found when comparing currently treated (with phosphate and alfacalcidol) (n = 11) and untreated (n = 16) XLH patients with their respective controls. We found no significant associations with treatment status and indices of bone remodeling or sclerostin although sclerostin tended to be increased in untreated versus treated (p = 0.06). In contrast to previous histomorphometric studies suggesting a low remodeling activity in XLH, these biochemical indices suggest high osteoblast and osteoclast activity. Further studies are needed to ascertain if the higher sclerostin level in XLH is related to osteocyte dysfunction or represents a secondary phenomenon.

Impact of Conventional Medical Therapy on Bone Mineral Density and Bone Turnover in Adult Patients with X-Linked Hypophosphatemia: A 6-Year Prospective Cohort Study

X-linked hypophosphatemia (XLH) is a rare, inheritable disorder manifesting as rickets in children and osteomalacia in adults. While conventional medical treatment with oral phosphate and alfacalcidol is recommended in childhood, it is undecided whether adults should continue therapy. The aim of this 6-year prospective study was to determine the impact of conventional medical treatment on areal bone mineral density (aBMD), bone turnover markers (BTMs) and measures of calcium homeostasis in 27 adult patients with XLH, 11 of whom received medical treatment. Lumbar spine and total hip aBMD, as assessed by DXA, and biochemical measures of calcium, phosphate, PTH, 1,25 dihydroxyvitamin D₂₊₃ (1,25(OH)₂D), fibroblast growth factor 23 (FGF23), P1NP and CTX were measured at baseline and at follow-up. The renal tubular reabsorption of PO₄ (TmPO₄/GFR) was calculated at both time points. Multilevel mixed-effects linear regression models were used for analyses. During the study period, spine and hip aBMD did not change significantly between treated and non-treated XLH patients. There was a trend towards a decrease in calcium, phosphate and TmPO₄/GFR in the treatment group (p = 0.057, p = 0.080 and p = 0.063, respectively), whereas PTH, FGF23, 1,25(OH)₂D and P1NP did not change significantly in either groups. However, CTX increased significantly in the treated compared to non-treated group (p = 0.044). Continuing conventional medical therapy in adulthood, although associated with increased bone resorption, does not promote or prevent loss of bone mass as evidenced from the stable aBMD of the hip and spine in XLH patients.

Chronic diseases in the children of women with maternal thyroid dysfunction: a nationwide cohort study

Objective

Maternal thyroid disease (TD) during pregnancy is associated with adverse birth outcomes, but little is known on its long-term outcomes. We aimed to examine if children born to mothers with TD have increased disease risk during childhood and adolescence.

Patients and methods

A register-based cohort study was conducted on all live born children in Denmark from 1989 to 2013, including the association between maternal TD during pregnancy and somatic and psychiatric diseases in the children. Cox proportional hazards models were used to compute hazard ratios (HRs) according to the type of maternal TD, Graves’ disease, and Hashimoto’s thyroiditis.

Results

A total of 2,618 children were born to women with Graves’ disease, 760 to women with Hashimoto’s thyroiditis (exposed), and 1,557,577 to women without any TD (unexposed). The median follow-up time for children born to mothers with Graves’ disease was 9.3 years (25/75 percentile 5.4/13.9 years) and with Hashimoto’s thyroiditis was 4.8 years (25/75 percentile 2.5/8.2 years). In children exposed to maternal Graves’ disease in utero, the adjusted HR of TD was 12.83 (95% CI, 9.74–16.90), Graves’ disease was 34.3 (95% CI, 20.23–58.35), and type 1 was diabetes 2.47 (95% CI, 1.46–4.18). In children exposed to maternal Hashimoto’s thyroiditis, the adjusted HR of Hashimoto’s thyroiditis was 24.04 (95% CI, 5.89–97.94).

Conclusion

Our data suggest that children born to women with Graves’ disease and Hashimoto’s thyroiditis have excess long-term morbidities in childhood and adolescence. We particularly found an increased risk of any TD and type 1 diabetes to be diagnosed in children exposed in utero to Graves’ disease. These novel findings are relevant for pediatricians, stressing the importance of history of maternal disease when evaluating children with suspected endocrine disorders.

A radiological study on intra- and extra-cranial calcifications in adults with X-linked hypophosphatemia and associations with other mineralizing enthesopathies and childhood medical treatment

OBJECTIVES

1) The objective of this study was to explore radiological signs of intracranial and nuchal ligament calcifications in adult patients with X-linked hypophosphatemia (XLH) compared with controls and 2) to correlate signs of cranial calcifications in XLH patients with the presence of other extra-cranial enthesopathies, with the severity of skeletal XLH impact and with medical treatment during childhood.

SETTING AND SAMPLE POPULATION

Lateral and postero-anterior cephalograms from 36 adult XLH patients and 49 adult controls and X-rays from spine, pelvis, knees and ankles from 31 of the 36 XLH patients.

METHODS

Radiological signs of intracranial and nuchal ligament calcifications in XLH patients were compared with controls by Fischer's exact test. In XLH patients, the presence of cranial calcifications was correlated with the presence of other enthesopathies, with the severity of skeletal XLH impact and with medical treatment by Fischer's exact or chi-squared test.

RESULTS

Six (17%) XLH patients revealed major signs of intracranial calcifications. Nuchal ligament calcifications were common in XLH patients compared with controls (p = 0.018). Enthesopathy was present at 0-24 sites per XLH patient (median 2). Intracranial calcifications trended to correlate positively with vertebral enthesopathies (p = 0.059). Nuchal calcifications correlated positively with the severity of skeletal XLH impact (p = 0.040). Vertebral enthesopathies correlated negatively with medical treatment (p = 0.008).

CONCLUSION

More XLH patients than controls showed nuchal ligament calcifications, and some XLH patients showed intracranial calcifications. Severely affected XLH patients often had nuchal ligament calcifications. Medically treated XLH patients had few vertebral enthesopathies.

A novel inverse association between cord 25-hydroxyvitamin D and leg length in boys up to three years. An Odense Child Cohort study

Background and aim

Long standing vitamin D deficiency in children causes rickets with growth impairment. We investigated whether sub-ischial leg length (SLL) is shorter, and cephalo-caudal length:length (CCL:L) ratio and sitting height:height (SH:H) ratio larger, with lower cord s-25-hydroxyvitamin D (25OHD) in the population-based prospective Odense Child Cohort, Denmark.

Methods

We included healthy singletons born to term with available measures of cord 25OHD and anthropometrics up to three years’ age. Linear regression was stratified by sex a priori and adjusted for maternal ethnicity, pre-pregnancy body mass index and smoking during pregnancy, season of blood sampling and child age.

Results

Median (IQR) cord 25OHD was 48.0 (34.0–62.4) nmol/L. At mean age 19.1 months, n = 504, mean (SD) SLL was 31.7 (1.7) cm; CCL:L-ratio 0.62 (0.01). At 36.3 months, n = 956, mean SLL was 42.9 (2.0) cm; SH:H-ratio 0.56 (0.01). No participants had rickets. In adjusted analyses, 19-months-old boys had 0.1 cm shorter SLL (p = 0.009) and 0.1% higher CCL:L-ratio (p = 0.04) with every 10 nmol/L increase in cord 25OHD. Similar findings were seen for late pregnancy 25OHD. In the highest cord 25OHD quartile (>60.7 nmol/L), SLL was 0.8 cm shorter (95% C.I.: 1.36;-0.29, linear trend, p = 0.004), and CCL:L-ratio 0.8% higher (95% C.I. 8.0x10^-05;0.01, linear trend, p = 0.01), compared to lowest quartile (<30.7 nmol/L). Similar associations with cord 25OHD were observed in 3-year-old boys. No consistent associations between 25OHD and anthropometrics were seen in girls at either age.

Conclusion

No leg shortening was found with decreasing cord s-25OHD in a healthy population of infants. A small, yet significant inverse association between cord 25OHD and SLL in boys 1½-3 years warrants further investigations.

Administering different levels of parenteral phosphate and amino acids did not influence growth in extremely preterm infants

AIM

When a new high amino acid parenteral nutrition (PN) solution was introduced to our hospital, a design error led to decreased phosphate levels. This prompted us to examine the effect of three different PN solutions on plasma phosphate, plasma calcium and weight increases on extremely preterm infants.

METHOD

This was a retrospective study of 186 infants with a gestational age of <28 weeks during their first month of life. They were divided into three groups based on the PN they received during hospitalisation. Group one received high levels of phosphate and low levels of amino acids. Group two received low levels of phosphate and high levels of amino acids. Group three received high levels of both phosphate and amino acids.

RESULTS

The lowest plasma phosphate values varied significantly between groups one (1.80 ± 0.46 mmol/L), two (1.05 ± 0.48 mmol/L) and three (1.40 ± 0.37 mmol/L) (p < 0.001), but no significant difference in weight increase was seen (p = 0.497).

CONCLUSION

The phosphate content of the PN influenced plasma phosphate and plasma calcium levels, but increasing the levels of both phosphate and amino acids did not improve weight gain during the first month of life.

Morphological characteristics of frontal sinus and nasal bone focusing on bone resorption and apposition in hypophosphatemic rickets

OBJECTIVES

To characterize the size and the morphology of the frontal sinus (i.e., structure evolved by bone resorption) and the nasal bone (i.e., structure evolved by bone formation) in adults with hypophosphatemic rickets (HR) compared with controls.

SETTING AND SAMPLE POPULATION

Thirty-six patients with HR (12 males and 24 females) aged 21-74 years were included. The control group comprised 49 healthy individuals (23 males and 26 females) aged 20-79 years.

MATERIAL AND METHODS

Profile cephalograms were obtained and the following measurements were included: height and width of the frontal sinus; length, width, and area of the nasal bone. The morphology of the nasal bone was assessed. Linear regression analyses were used to compare HR patients with controls.

RESULTS

In HR patients, the size of the frontal sinus was unaffected (p = 0.406 to p = 0.862). The proximal width of the nasal bone, and the ratio between the proximal width and the axial length of the nasal bone were increased in HR patients (p < 0.05).

CONCLUSIONS

The size of the frontal sinus was unaffected, indicating a normal ability of bone resorption within the bone. The morphology of the nasal bone was abnormal indicating a disturbance in bone formation during growth. The disturbances in nasal bone modeling were mainly expressed in the proximal part supported by structures of cartilaginous origin.

Higher bone mineral density at six years of age in very preterm-born infants fed human milk compared to formula feeding. A secondary analysis of an RCT

In very preterm-born infants, nutritional intake is important to reduce the risk of severe metabolic bone disease including the risk of a lower bone mineral density (BMD). The aim of this study was to evaluate bone mineral content (BMC) and BMD (measured as BMC per bone area (BA)) at six years of age in very preterm-born infants fed different diets post-discharge. Data on this topic so far is insufficient, and with this study we aim to supply more useful data. A prospective follow-up study of 281 children born very preterm (gestational age ≤ 32 + 0 weeks) and enrolled in a multicentre RCT on post-discharge nutrition. Infants fed human milk (HM) were randomised respectively to be fed unfortified HM (UHM) or fortified human milk (FHM) from hospital discharge to four months' corrected age. Those not fed HM received a preterm formula (PF). At six years of age, BMD and BMC in all the children were established by means of a dual-energy X-ray absorptiometry (DXA) scan (Lunar Prodigy) and adjusted for sex, age, and anthropometrics. A total of 192 very preterm-born children (59 fed UHM, 67 FHM and 66 PF) had a DXA scan performed at median 6 (5.8-8.3) years of age. No significant difference was found comparing UHM and FHM according to height, weight, BA, BMC, and BMD at six years of age. However, a multiple regression analysis showed significantly improved BMD in breastfed children compared to PF-fed children.

CONCLUSIONS

Fortified compared to non-fortified human milk post-discharge did not have an impact on BMD at 6 years of age in very preterm-born infants. Breastfed children demonstrated higher BMD than formula-fed children.

WHAT IS KNOWN

• Adequate nutritional intake is important to improve growth and to reduce the risk of severe bone disease in very preterm born infants. • Bone mineralization is attained later in preterm born infants compared to term born infants.

WHAT IS NEW

• Feeding human milk with fortification compared to non-fortified human milk did not improve bone mineral density in children born very preterm in this follow-up study at six years of age. • Feeding human milk compared to formula was associated with increased BMD at six years of age among very preterm born infants.

Giant cell tumour of bone in os sacrum of a prepubertal girl - Surgical and medical treatment with zoledronate and denosumab

A giant cell tumour of bone presented in the os sacrum of a prepubertal girl. Surgery with reconstruction was performed, but total resection was impossible. Zoledronate failed to avoid tumour regrowth, and treatment was changed to denosumab, despite not being recommended for use in growing children. Denosumab treatment for 21 months reduced and stabilized tumour size, the girl became pain free with asymptomatic side effects as mild hypocalcemia, hypophosphatemia and sclerosis of newly formed bone.

Systematic Review: Efficacy of Medical Therapy on Outcomes Important to Adult Patients with X-Linked Hypophosphatemia

OBJECTIVE

To examine the highest certainty evidence addressing the management of X-linked hypophosphatemia (XLH) in adults to inform treatment recommendations.

METHODS

We searched Embase, MEDLINE, Web of Science, and Cochrane Central up to May 2023. Eligible studies included RCTs and observational studies of individuals 18+ with clinically or genetically confirmed XLH. Manuscripts comparing burosumab to no treatment or conventional therapy (phosphate and active vitamin D) and conventional therapy to no treatment were included. Two reviewers independently determined eligibility, extracted data, and assessed risk of bias (RoB). GRADE methodology was used to assess evidence certainty.

RESULTS

We screened 4,114 records, after removing duplicates, and assessed 254 full texts. One RCT and two observational studies were eligible. The RCT of burosumab versus no treatment had low RoB. Burosumab probably improves pain from fracture/pseudofracture healing (moderate certainty) but has little or no impact on direct pain measures (moderate certainty). Burosumab may reduce the need for parathyroidectomy (low certainty) but has little or no impact on fatigue (high certainty), stiffness (moderate certainty), and mobility (low certainty) over 24 weeks. Burosumab may increase dental abscess risk (low certainty). Indirect evidence comparing burosumab to conventional therapy provided low certainty regarding burosumab versus conventional therapy. Two observational studies on conventional therapy versus no treatment had high RoB and very low certainty regarding the impact of conventional therapy on patient-important outcomes.

CONCLUSION

No formal comparisons between burosumab and conventional therapy in adults exist. Evidence for conventional therapy versus no treatment is very uncertain. Our review highlights the need for more data on the long-term effects of burosumab and conventional therapy on patient-important outcomes in adult patients with XLH.

Treatment of hypophosphataemic rickets in children remains a challenge

INTRODUCTION

Hypophosphataemic rickets (HR) is a rare hereditary disease characterised by hypophosphataemia, defects in bone mineralisation and rickets.

MATERIAL AND METHODS

We searched the hospital files at H.C. Andersen Children's Hospital, Odense University Hospital, Denmark, for children with the International Classification of Diseases 10 codes E83.3B (vitamin D resistant rickets) and E83.3A1 (familiar hypophosphataemia) from 1 February 2012 to 1 May 2012. Data were collected retrospectively.

RESULTS

Fifteen HR children were identified. X-linked hypophosphataemia with mutations in the phosphate-regulating endopeptidase homologue, X-linked were present in 80%; three had autosomal recessive HR with dentin matrix protein mutations. The children were treated with phosphate and alphacalcidol for an average of 7.7 years ± 5.1 standard deviations (SD). At the latest follow-up, the mean age was 10.1 (+5.4) years, and the mean height had declined 0.8 SD from the first contact. A total of 40% had an actual height below -2.0 SD, and 40% underwent surgery for leg deformities. Among the medically treated patients, five had genu varus with a mean medial femoral condyle distance of 6.6 cm (+ 2.79), and two patients had genu valgus with a mean medial malleolus distance of 12.3 cm (+ 1.77). Episodes of secondary hyperparathyroidism were seen in 87%, and one patient developed transient nephrocalcinosis.

CONCLUSION

The current medical treatment for HR is insufficient. The rarity of the disease and the treatment difficulties of HR call for centralised management. International multi-centre trials including novel treatment options are warranted.

The International X-Linked Hypophosphatemia (XLH) Registry: first interim analysis of baseline demographic, genetic and clinical data

BACKGROUND

X-linked hypophosphatemia (XLH) is a rare, hereditary, progressive, renal phosphate-wasting disorder characterized by a pathological increase in FGF23 concentration and activity. Due to its rarity, diagnosis may be delayed, which can adversely affect outcomes. As a chronic disease resulting in progressive accumulation of musculoskeletal manifestations, it is important to understand the natural history of XLH over the patient's lifetime and the impact of drug treatments and other interventions. This multicentre, international patient registry (International XLH Registry) was established to address the paucity of these data. Here we present the findings of the first interim analysis of the registry.

RESULTS

The International XLH Registry was initiated in August 2017 and includes participants of all ages diagnosed with XLH, regardless of their treatment and management. At the database lock for this first interim analysis (29 March 2021), 579 participants had entered the registry before 30 November 2020 and are included in the analysis (360 children [62.2%], 217 adults [37.5%] and 2 whose ages were not recorded [0.3%]; 64.2% were female). Family history data were available for 319/345 (92.5%) children and 145/187 (77.5%) adults; 62.1% had biological parents affected by XLH. Genetic testing data were available for 341 (94.7%) children and 203 (93.5%) adults; 370/546 (67.8%) had genetic test results; 331/370 (89.5%) had a confirmed PHEX mutation. A notably longer time to diagnosis was observed in adults ≥ 50 years of age (mean [median] duration 9.4 [2.0] years) versus all adults (3.7 [0.1] years) and children (1.0 [0.2] years). Participants presented with normal weight, shorter length or height and elevated body mass index (approximately - 2 and + 2 Z-scores, respectively) versus the general population. Clinical histories were collected for 349 participants (239 children and 110 adults). General data trends for prevalence of bone, dental, renal and joint conditions in all participants were aligned with expectations for a typical population of people with XLH.

CONCLUSION

The data collected within the International XLH Registry, the largest XLH registry to date, provide substantial information to address the paucity of natural history data, starting with demographic, family history, genetic testing, diagnosis, auxology and baseline data on clinical presentation.