Vitamin D and bone health: What vitamin D can and cannot do.

Historically vitamin D deficiency had devastating consequences for children causing rickets resulting in severe bone deformities often leading to death. The mystery of the cause of rickets finally came to light when it was observed that cod liver oil and sunlight could prevent and cure rickets. The first vitamin D to be discovered was vitamin D2 from ergosterol in ultraviolet irradiated yeast. Vitamin D3 was discovered from UV exposure to the skin. Investigations revealed the two major functions of vitamin D were to increase intestinal calcium and phosphate absorption and mobilize calcium from the skeleton to maintain calcium and phosphorus homeostasis. Later studies demonstrated that vitamin D does not have an active role in bone mineralization. Vitamin D deficiency results in secondary hyperparathyroidism increasing bone resorption. As a result, this decreases bone mineral content and compromises the architectural integrity increasing risk for fracture. Vitamin D deficiency has also been shown to enhance aging of the bone causing cracks and enhancing bone fractures. Vitamin D deficiency also causes osteomalacia. Therefore, vitamin D sufficiency is extremely important to maximize bone health throughout life. It helps to prevent bone loss, but it cannot restore bone loss due to increased bone resorption that can occur under a variety of circumstances including menopause. The Endocrine Society Guidelines recommends for all ages that adequate vitamin D obtained from the sun, foods and supplements is necessary in order to maintain a circulating concentration of 25-hydroxyvitamin D of at least 30 ng/mL for maximum bone health.

Vitamin D deficiency or resistance and hypophosphatemia.

Vitamin D is mainly produced in the skin (cholecalciferol) by sun exposure while a fraction of it is obtained from dietary sources (ergocalciferol). Vitamin D is further processed to 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D (calcitriol) in the liver and kidneys, respectively. Calcitriol is the active form which mediates the actions of vitamin D via vitamin D receptor (VDR) which is present ubiquitously. Defect at any level in this pathway leads to vitamin D deficient or resistant rickets. Nutritional vitamin D deficiency is the leading cause of rickets and osteomalacia worldwide and responds well to vitamin D supplementation. Inherited disorders of vitamin D metabolism (vitamin D-dependent rickets, VDDR) account for a small proportion of calcipenic rickets/osteomalacia. Defective 1α hydroxylation of vitamin D, 25 hydroxylation of vitamin D, and vitamin D receptor result in VDDR1A, VDDR1B and VDDR2A, respectively whereas defective binding of vitamin D to vitamin D response element due to overexpression of heterogeneous nuclear ribonucleoprotein and accelerated vitamin D metabolism cause VDDR2B and VDDR3, respectively. Impaired dietary calcium absorption and consequent calcium deficiency increases parathyroid hormone in these disorders resulting in phosphaturia and hypophosphatemia. Hypophosphatemia is a common feature of all these disorders, though not a sine-qua-non and leads to hypomineralisation of the bone and myopathy. Improvement in hypophosphatemia is one of the earliest markers of response to vitamin D supplementation in nutritional rickets/osteomalacia and the lack of such a response should prompt evaluation for inherited forms of rickets/osteomalacia.

Global Health Disparities in Childhood Rickets.

Nutritional rickets is a global health problem reflecting both historical and contemporary health disparities arising from racial, ethnic, environmental, and geopolitical circumstances. It primarily affects marginalized populations and can contribute to long-term morbidity. Deficits in bone health in childhood may also contribute to osteomalacia/osteoporosis. Solutions require a global public health approach.

Assessment, treatment and prevention of vitamin D deficiency.

Vitamin D deficiency is prevalent among various groups in the UK, and can result from insufficient sunlight exposure and dietary intake. There is a population-wide recommendation of 10 micrograms (400 international units) of vitamin D per day, with a daily supplement advised. However, supplement use is often suboptimal, compounding the risk of deficiency. Long-term vitamin D deficiency can cause rickets in children and osteomalacia or osteoporosis in adults. Therefore, it is important that nurses recognise which groups are at increased risk of vitamin D deficiency and understand how to assess people's vitamin D status. Nurses also need to be able to support the prevention and treatment of low vitamin D levels, which typically involves supplementation and lifestyle changes.

Vitamin D Deficiency in Chronic Childhood Disorders: Importance of Screening and Prevention.

Vitamin D plays a vital role in regulating calcium and phosphate metabolism and maintaining bone health. A state of prolonged or profound vitamin D deficiency (VDD) can result in rickets in children and osteomalacia in children and adults. Recent studies have demonstrated the pleiotropic action of vitamin D and identified its effects on multiple biological processes in addition to bone health. VDD is more prevalent in chronic childhood conditions such as long-standing systemic illnesses affecting the renal, liver, gastrointestinal, skin, neurologic and musculoskeletal systems. VDD superimposed on the underlying disease process and treatments that can adversely affect bone turnover can all add to the disease burden in these groups of children. The current review outlines the causes and mechanisms underlying poor bone health in certain groups of children and young people with chronic diseases with an emphasis on the proactive screening and treatment of VDD.

Not all the bowlegs is rickets! (a case report).

Bowing of the legs is common in childhood. Most times it is considered to be rickets without considering other possibilities. Blount´s disease is a close differential diagnosis which is developmental deformity characterized by intorsion of tibia leading to varus angulation. This case report aims to encourage pediatricians to expand their vision and consider other possibilities when a case of bowing of legs is encountered. Here we report a case of a four-year-old boy with bowing of both legs noticed first at 2.5 years of age. There was no history suggestive of trauma. Development of the child was age appropriate in all domains. He was receiving treatment for rickets for 1.5 years in form of oral vitamin D3 and calcium supplementations. He had no other clinical signs of rickets like frontal bossing, widening of wrists, and rachitic rosary except bowing of legs. His biochemical parameters did not show any alterations that would support the diagnosis of rickets. Weight-bearing radiographs of lower limbs showed medial intorsion of bilateral tibia with metaphyseo-diaphysial angle to be 25º on the right side and 20º on the left side, which was beyond the physiological normal angulation, therefore he was diagnosed as a case of Blount´s disease, stage III as per Langenskiöld classification. All the bow legs is not always rickets in pediatric practice. Therefore, various differential diagnoses should be kept in mind as early diagnosis and intervention can change a child´s life.

Rickets guidance: part II-management.

Here, we discuss the management of different forms of rickets, including new therapeutic approaches based on recent guidelines. Management includes close monitoring of growth, the degree of leg bowing, bone pain, serum phosphate, calcium, alkaline phosphatase as a surrogate marker of osteoblast activity and thus degree of rickets, parathyroid hormone, 25-hydroxyvitamin D3, and calciuria. An adequate calcium intake and normal 25-hydroxyvitamin D3 levels should be assured in all patients. Children with calcipenic rickets require the supplementation or pharmacological treatment with native or active vitamin D depending on the underlying pathophysiology. Treatment of phosphopenic rickets depends on the underlying pathophysiology. Fibroblast-growth factor 23 (FGF23)-associated hypophosphatemic rickets was historically treated with frequent doses of oral phosphate salts in combination with active vitamin D, whereas tumor-induced osteomalacia (TIO) should primarily undergo tumor resection, if possible. Burosumab, a fully humanized FGF23-antibody, was recently approved for treatment of X-linked hypophosphatemia (XLH) and TIO and shown to be superior for treatment of XLH compared to conventional treatment. Forms of hypophosphatemic rickets independent of FGF23 due to genetic defects of renal tubular phosphate reabsorption are treated with oral phosphate only, since they are associated with excessive 1,25-dihydroxyvitamin D production. Finally, forms of hypophosphatemic rickets caused by Fanconi syndrome, such as nephropathic cystinosis and Dent disease require disease-specific treatment in addition to phosphate supplements and active vitamin D. Adjustment of medication should be done with consideration of treatment-associated side effects, including diarrhea, gastrointestinal discomfort, hypercalciuria, secondary hyperparathyroidism, and development of nephrocalcinosis or nephrolithiasis.

Rickets manifestations in a child with metaphyseal anadysplasia, report of a spontaneously resolving case.

INTRODUCTION: Rickets is not an unusual diagnosis for pediatricians even currently in developed countries. Children typically present with leg bowing, enlargement of wrists, rachitic rosary (swelling of costochondral junctions) and/or waddling gait. But not every child with growth delay and enlarged metaphyses is diagnosed with rickets. Metaphyseal anadysplasia (MAD) is a disorder of variable severity with metaphyseal flaring and irregularities, without vertebral abnormalities. MAD is characterized by an early onset and a regressive course in late childhood without treatment, despite persistent short stature. Autosomal dominant or recessive variants in the matrix metalloproteinase 13 gene (MMP13) are responsible for these transient metaphyseal changes. CASE PRESENTATION: We report a new pathogenic heterozygous variant in MMP13 (NM_002427.4: c.216G>C, p.Gln72His) in a toddler, initially thought to have rickets, and his father, with MAD phenotypes. Additionally, we review the seven reported MMP13 variants. CONCLUSION: One should keep a wide differential diagnosis in cases of suspected rickets, including skeletal dysplasias which might have a regressive course.

Nutritional Rickets Due to Severe Food Selectivity in Autism Spectrum Disorder.

OBJECTIVE: Studies have detected differences in various measures of bone health between individuals with autism spectrum disorder (ASD) and their peers. However, these measures do not amount to direct clinical evidence of increased orthopedic pathology in this population. Some of the most compelling evidence to this effect comes from case reports of nutritional rickets in children with ASD. We report on 1 such case that, to our knowledge, is the first report of nutritional rickets in ASD necessitating corrective surgery. METHODS: Case report, review of relevant literature, and implications for further research. RESULTS: An 11-year-old girl with ASD was admitted for postoperative medical comanagement after successful repair of bilateral genu valgum (knock knees). On admission, the patient's mother reported that the patient was a "picky eater." No cause had been determined preoperatively, although the deformity had developed at 10 years of age, thereby qualifying as pathologic. The medical team considered rickets because of the patient's limited diet. Subsequent laboratory work demonstrated hypocalcemia, vitamin D deficiency, and secondary hyperparathyroidism. The patient was diagnosed with nutritional rickets due to inadequate vitamin D intake, a consequence of severe food selectivity associated with ASD. CONCLUSION: This case exemplifies the extreme orthopedic and metabolic complications that can result from food selectivity in children with ASD, pointing to the need for further research into the prevalence and causes of orthopedic pathology and nutritional rickets in this population. The case also underscores the need for evidence-based guidelines to prevent orthopedic pathology in children with ASD.

Rickets in association with skin diseases and conditions: A review with emphasis on screening and prevention.

BACKGROUND: Rickets is a common disease worldwide. In the developed world, its prevalence dramatically decreased but still diagnosed in at-risk populations. The skin plays a critical role in vitamin D synthesis. Therefore, several skin diseases, especially keratinization disorders, could lead to impaired vitamin D metabolism and vitamin D deficient rickets. OBJECTIVE: The article aimed to summarize the current knowledge of skin diseases and conditions associated with rickets. METHODS: To examine the association between rickets and skin diseases, we performed a systematic review of the literature using PubMed database. The search included studies published from the database inception to August 2019. RESULTS: A total number of 75 articles were included. Identified conditions associated with rickets were ichthyosis being a more common skin diseases, alopecia, epidermal and melanocytic nevi, xeroderma pigmentosum, mastocytosis, psoriasis, and atopic dermatitis. Three types of rickets were identified: vitamin D-dependent rickets, hypocalcemic vitamin D-dependent rickets type 2, and hypophosphatemic rickets. Cutaneous skeletal hypophosphatemia syndrome is a newly described and under-recognized condition. It is defined by the association of epidermal or melanocytic nevi, hypophosphatemic rickets, and elevated levels of fibroblast growth factor 23. Rickets in patients with ichthyosis was mainly due to impaired ability of ichthyotic skin to synthesize vitamin D, poor UV penetration of the skin caused by keratinocyte proliferation, and dark phototype. The latter may be considered a risk factor for rickets in patients with ichthyosis. CONCLUSION: Despite its rarity, these associations should be properly recognized by dermatologists. Early diagnosis of rickets is important to prevent growth retardation and skeletal deformities.

[MODERN ISSUES OF D-VITAMIN SIGNIFICANCE IN DEVELOPMENT OF FULERUM-MOVE DEVICES OF INFANTS, CHILDREN AND ADOLESCENTS ( REVIEW)].

The purpose of this review is the study of literature for the current data on the metabolism of vitamin D and its role in development of bone tissue in children. The role of the main marker enabling assessing 25(OH)D concentration in the body the reference values has been analyzed. Summarizing the literature data, we may say that vitamin D and calcium deficiencies are common worldwide, causing nutritional rickets and osteomalacia, which have a mayor impact on health of infants, children and adolescents.

Mutation of SGK3, a Novel Regulator of Renal Phosphate Transport, Causes Autosomal Dominant Hypophosphatemic Rickets.

CONTEXT: Hypophosphatemic rickets (HR) is a group of rare hereditary renal phosphate wasting disorders caused by mutations in PHEX, FGF23, DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3. OBJECTIVE: A large kindred with 5 HR patients was recruited with dominant inheritance. The study was undertaken to investigate underlying genetic defects in HR patients. DESIGN: Patients and their family members were initially analyzed for PHEX and FGF23 mutations using polymerase chain reaction sequencing and copy number analysis. Exome sequencing was subsequently performed to identify novel candidate genes. RESULTS: PHEX and FGF23 mutations were not detected in the patients. No copy number variation was observed in the genome using CytoScan HD array analysis. Mutations in DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3 were also not found by exome sequencing. A novel c.979-96 T>A mutation in the SGK3 gene was found to be strictly segregated in a heterozygous pattern in patients and was not present in normal family members. The mutation is located 1 bp downstream of a highly conserved adenosine branch point, resulted in exon 13 skipping and in-frame deletion of 29 amino acids, which is part of the protein kinase domain and contains a Thr-320 phosphorylation site that is required for its activation. Protein tertiary structure modelling showed significant structural change in the protein kinase domain following the deletion. CONCLUSIONS: The c.979-96 T>A splice mutation in the SGK3 gene causes exon 13 skipping and deletion of 29 amino acids in the protein kinase domain. The SGK3 mutation may cause autosomal dominant HR.

Oral manifestations of renal tubular acidosis associated with secondary rickets: case report / Manifestações bucais da acidose tubular renal associada ao raquitismo secundário: relato de caso

ABSTRACT This report describes the oral manifestations of renal tubular acidosis (RTA) associated with secondary rickets and discusses the biological plausibility of these findings. The characteristic electrolyte changes during RTA or genetic mutations that trigger RTA may be responsible for impaired amelogenesis, dental malocclusion, impacted teeth, and absent lamina dura. This report reinforces the possibility of an association between RTA and the oral manifestations described.

RESUMO Este relato de caso descreve as manifestações bucais da acidose tubular renal (ATR) associada ao raquitismo secundário e discute a plausibilidade biológica desses achados. As alterações eletrolíticas características da ATR ou as mutações genéticas que a desencadeiam podem ser responsáveis pela amelogênese imperfeita, maloclusão dentária, dentes impactados e ausência de lâmina dura. Este relato reforça a possibilidade de uma associação entre ATR e as manifestações bucais descritas.

Vitamin D: part II; cod liver oil, ultraviolet radiation, and eradication of rickets.

PURPOSE: After Glisson's description of rickets, it took two centuries to realize that rickets was due to the absence of antirachitic nutrients in the diet or lack exposure of the skin to ultraviolet rays. This bone disease caused by vitamin D deficiency was one of the most common diseases of children 100 years ago. This paper explores how the definition, diagnosis, and treatment of rickets shifted in the first decades of the twentieth century. MATERIAL AND METHODS: Although benefits of cod liver oil as food were known as early as the seventh century, cod liver oil was only proposed as medicinal for rickets in Northern Europe at the end of the eighteenth century. The relationship between rickets and nutritional deficiency was suspected and demonstrated between 1880 and 1915, at the same time of the discovery of other vital substances (vitamins) needed to prevent beriberi, scurvy, and pellagra. Understanding that the lack of photosynthesized vitamin D or the lack of dietary vitamin D was a similar risk of rickets was an important turn in the comprehension of the disease. We look at the sequence and turn of events related to the discovery of vitamin D. RESULTS: Rickets has been recognized first as a disease of urban living people. Cod liver oil had been used since 1700 as a nonspecific treatment for a range of diseases. Generations of children in cities of the north of Europe had learned to hate the taste and smell of the black oily liquid and then grown up to be parents who, in turn, hated to force it down their children's throats. Occasional papers before 1900 pointed to its efficacy for rickets, and most textbooks of the early 1900s mentioned it only as a treatment option. The discovery in the early 1900s that artificial and natural ultraviolet rays had both antirachitic activity allowed to produce antirachitic foods just by food irradiation with artificial ultraviolet irradiation. Clinical guidelines were adopted to propose exposure to sunlight or to artificial ultraviolet radiation to prevent rickets in children. By the mid-1920s, rickets was promoted as universal, at times invisible to non-experts, but present to some degree in nearly every young child regardless of race or class. It was thus used to promote the young disciplines of preventive medicine, pediatrics, and public health. Innovative advances were made in the understanding of vitamin D synthesis from 1915 to 1935. A public health campaign of the 1930s was a success to eradicate rickets, using irradiated ergosterol from yeast to enrich milk and other foods with vitamin D, ensuring that the general population was consuming sufficient vitamin D. CONCLUSION: Rickets therefore provides an excellent window into the early politics of preventive health and the promotion of targeted interventions in the world. It is also a relevant historical counterpoint for current debates over the role of risk factors (absence of light or sun) for disease (today's so-called "lifestyle" diseases).

Selective rickets from localized advanced maturation-a case report.

An unusual cause of rickets is illustrated by a patient with infantile multisystem inflammatory disease who, by age 2 years and 4 months, developed striking radiographic and clinical rickets restricted to those joints involved by the inflammatory process. The locally increased vascularity from his inflammation led to increased maturation at those sites so rapid as to override the usual enchondral calcification, thus causing a rickets pattern. Other sites, such as the proximal humeri, lacking any inflammation, showed no increased maturation rate and did not manifest local rickets. Rapid local bone maturation may cause localized rickets.

Vitamin D insufficiency: Definition, diagnosis and management.

Severe vitamin D deficiency can be defined as the dose of vitamin D or serum 25OHD concentrations needed to prevent nutritional rickets or osteomalacia. There is large international consensus that these diseases can be prevented by 400 IU of vitamin D/d and 25OHD above 30 nmol/l (12 ng/ml). Vitamin D deficiency can also accelerate the risk of fractures and probably also of falls in elderly subjects but there is no consensus on the required daily doses or minimal 25OHD threshold for these endpoints. The majority of experts consider 800 IU/d and serum 25OHD above 50 nmol/l (20 ng/ml) as sufficient, with a minority opinion aiming for 75 nmol/l or even higher. For other extra-skeletal endpoints, no hard evidence is available to define whether or not this is causally related to vitamin D status. Therefore, for these endpoints no minimal dosage or 25OHD threshold can be defined.

[Rickets/Osteomalacia. Consensus on Vitamin D Deficiency and Insufficiency in Children.]

Vitamin D deficiency is usually manifested as rickets in children. Since vitamin D deficiency/insufficiency is common worldwide, global consensus has been formulated on prevention, diagnosis and treatment of nutritional rickets represented by vitamin D-deficient rickets. This consensus has defined vitamin D insufficiency as the status with serum 25-hydroxyvitamin D(25OHD)level between 12 and 20 ng/mL and vitamin D deficiency as the status with serum 25OHD level below 12 ng/mL. Generally low dietary calcium(Ca)intake coexists with vitamin D deficiency/insufficiency in patients with rickets, and it is important to ensure sufficient Ca intake ensure in the management of nutritional rickets.

[Rickets and anaemia caused by coeliac disease in a three-year-old girl].

We present a case report of a three-year-old girl of Pakistani origin with coeliac disease. The first symptom was spontaneous fracture of the fibula. Vitamin D deficiency rickets and iron deficiency anaemia were demonstrated. An intestinal biopsy and elevated antibody levels confirmed the coeliac disease. Rickets is a known but rare presentation of coeliac disease, but this case report illustrates, how coeliac disease in children often presents with non-gastrointestinal symptoms. The importance of investigations for malabsorp-tion, if iron deficiency is not easily corrected with sufficient iron supplements, is underlined as well as the importance of screening for coeliac disease.

Implications of vitamin D toxicity & deficiency.

Vitamin D deficiency is an increasing problem affecting all ages. Patients should be assessed for risk factors as part of preventive health maintenance. Vitamin D toxicity is a rare occurrence caused by oversupplementation and errors in food fortification. The connection between vitamin D deficiency and osteoporosis, is well established. However, a cause and effect relationship has yet to be established between vitamin D deficiency and many chronic illnesses. An evidence-based approach is treating patients for an underlying vitamin D deficiency in hopes of improving many chronic illnesses.

Health Risks of Hypovitaminosis D: A Review of New Molecular Insights.

Hypovitaminosis D has become a pandemic, being observed in all ethnicities and age groups worldwide. Environmental factors, such as increased air pollution and reduced ultraviolet B (UVB) irradiation, as well as lifestyle factors, i.e., decreased outdoor activities and/or poor intake of vitamin D-rich food, are likely involved in the etiology of a dramatic reduction of vitamin D circulating levels. The insufficiency/deficiency of vitamin D has long been known for its association with osteoporosis and rickets. However, in the last few decades it has become a serious public health concern since it has been shown to be independently associated with various chronic pathological conditions such as cancer, coronary heart disease, neurological diseases, type II diabetes, autoimmune diseases, depression, with various inflammatory disorders, and with increased risk for all-cause mortality in the general population. Prevention strategies for these disorders have recently involved supplementation with either vitamin D2 or vitamin D3 or their analogs at required daily doses and tolerable upper-limit levels. This review will focus on the emerging evidence about non-classical biological functions of vitamin D in various disorders.