Vitamin D in Jordanian Infants Najwa Khuri-Bulos Professor of Pediatrics and Infectious Disease Jordan University Hospital

Outline about vitamin D Sources of vitamin D Classical action on bone Non classical functions Normal vitamin D intake Pts at risk of vitamin D deficiency Clinical manifestations of vitamin D deficiency Laboratory diagnosis of vitamin D deficiency Treatment Status of vitamin D in jordan with special reference to children Prevention of vitamin D deficiency

Vitamin D Rickets first described in the 17th century Relationship to fat soluble vitamin and dietary vitamin D in early 20th century . This is the only vitamin that is synthesized by human body by interaction of skin with sunshine Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by vitamin D

Vitamin D pathways for the two sources of vitamin D

Definition Vitamin D2, Ergosterol plant sources Vitamin D3 Cholecalciferol from skin also manufactured from lanolin 25,0H vitamin D Calcidiol 1,25 OH vitamin D Calcitriol

Vitamin D actions Vitamin D promotes calcium absorption in the gut Maintains adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and prevents hypocalcemic tetany. It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts

Vitamin D actions Actions on bone Increased Bone density Increased calcium and PO4 deposition Decreased osteoporotic fracture

Vitamin D actions Immune response Increased regulatory T cell Increased oxidative burst Increased Cathelicidin Decreased cytokine release

Vitamin D actions Pregnancy ?Decreased pre eclampsia Decreased myopathy Decreased calcium malabsorption Decreased bone loss ?Decreased risk of CS Mulligan et al, American Journal of Obstetric and Gynecology, 2010

Vitamin D action Pancreas Decreased insulin resistance Decreased type 1 diabetes Increased insulin secretion

Vitamin D actions Children Decreased SGA Decreased risk of rickets Decreased risk of hypocalcemia Infantile cardiomyopathy if deficient Decreased severity of RSV infection Increased incidence of asthma if deficient

Sources of vitamin D Normal diets < 10% Must be synthesized by the skin or taken as dietary supplement Skin, must have direct exposure to sunshine 10-15 minutes at noon hours Exposure not acceptable behind glass No sun block applied Dark skin people need more exposure to have same level of vitamin D

Vitamin D in the newborn Highly correlated with vitamin D in the pregnant mother. Fetus totally dependent on maternal sources of vitamin D and Calcium After birth, Breast milk is a very poor source of vitamin D, only 10-40 Units/Litre Hence Must supplement infants very early in life Infants need 400 IU/ per day Even formula fed babies need vitamin D supplementation

Vitamin D status 1 nmole/litre = 0.4 ngm /ml Vitamin D levels are Inversely related to parathormone levels These level off at 30-40 nanograms determined to be the adequate range Calcium absorption increased at > 30 nanograms

Vitamin D 25 OH levels and vitamin D status Definition <20ng/ml <50 mm/L Deficient 20-30ng/ml 50-75 mm/L Insufficient >30- ng/ml >75 mm/L Normal, optimal >150 ng/ml >375 mm/L Toxic

Vitamin D sources Dietary Supplementation Sunlight Wavelength 290-315 penetrates the skin and converts 7 dehydrocholesterol to previtamin D3 Any excess of these is destroyed by sunlight. There is no toxicity from sun exposure. Vitamin D from the skin and dietary sources is metabolized by the liver to become 25 OH and the final 1 hydroxylation step occurs in the kidney to lead to 1, 25 OH vitamin D which is the active form This final renal step is highly regulated by parathormone and serum calcium and PO4 levels

Sun exposure and vitamin D Ultraviolet (UV) B radiation with a wavelength of 290–320 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3.

Adequate intake of vitamin D per day Infants <12 month 400 IU Children >1 yr 600 IU Adults, pregnant 600 IU >70 yrs 800 IU Mainly obtained from fish and fortified foods or exposure to sunshine 1 ug=40 units

People at risk of vitamin D deficiency Breast fed infants Older adults People with limited sun exposure People with dark skin People with fat malabsorption People with BMI>30

Causes of vitamin D deficiency in children and adolescents Reduced intake or synthesis of vitamin D3 Being born to a vitamin D-deficient mother; dark-skinned women, or women of who actively avoid exposure to sunlight or are veiled Prolonged breastfeeding Dark skin colour Reduced sun exposure — chronic illness or hospitalisation, intellectual disability, and excessive use of sunscreen Low intake of foods containing vitamin D

Causes of vitamin D deficiency in children and adolescents Abnormal gut function or malabsorption Small-bowel disorders (eg, coeliac disease) Pancreatic insufficiency (eg, cystic fibrosis) Biliary obstruction (eg, biliary atresia)

Causes of vitamin D deficiency in children and adolescents Reduced synthesis or increased degradation of 25-OHD or 1,25-(OH)2D Chronic liver or renal disease Drugs: rifampicin, isoniazid and anticonvulsants

Osseous signs of vitamin D deficiency (common to less common) Swelling of wrists and ankles Rachitic rosary (enlarged costochondral joints felt lateral to the nipple line) Genu varum, genu valgum or windswept deformities of the knee Frontal bossing Limb pain and fracture Craniotabes (softening of skull bones, usually evident on palpation of cranial sutures in the first 3 months) Hypocalcaemia — seizures, carpopedal spasm Myopathy, delayed motor development Delayed fontanelle closure Delayed tooth eruption Enamel hypoplasia Raised intracranial pressure secondary hyperparathyroidism

Radiological features Cupping, splaying and fraying of the metaphysis of the ulna, radius and costochondral junction Coarse trabecular pattern of metaphysis Osteopenia Fractures

Treatment of Hypocalcemia < 1 month of age 10% calcium gluconate: 0.5 mL/kg (max 20 mL) intravenously over 30–60 minutes. Calcium: 40–80 mg/kg/day (1–2 mmol/kg/day) orally in 4–6 doses, Calcitriol ( vitamin D3) : 50–100 ng/kg/day or in 2–3 doses until serum calcium level is > 2.1 mmol/L or 8 mg/L

Treatment of vitamin D deficiency ACUTE Management Age < 1 month Vitamin D: 1000 IU (25 μg) daily for 3 months. Maintenance Vitamin D: 400 IU (10 μg) daily or 150 000 IU (3750 μg) at the start of autumn.‡ Monitoring 1 month: Serum calcium and alkaline phosphatase. 1-12 months Vitamin D: 3000 IU (75 μg) daily for 3 months, or 300 000 IU (7500 μg) over 1–7 day 3 months: Serum calcium, magnesium, phosphate, alkaline phosphatase, calcidiol, parathyroid hormone. Wrist x-ray to assess healing of rickets. Annual: Calcidiol. >12 months Vitamin D: 5000 IU (125 μg) daily for 3 months, or 500 000 IU (15 000 μg) over 1–7 days. Calcitriol , 1, 25 OH vitamin D, Calcidiol, 25 oh vitamin D

Adequate calcium intake Age Calcium intake 0-6 months 210 mg 6-12 months 270 mg 1-3 years 300 mg 4-8 years 800 mg 9-18 years 1300 mg

Recent Studies on vitamin D in Jordanians 2011, Batieha Et al Ann Nutr Met 37% females were deficient 5.6% of males were deficient 2010 Abdul Razzak , Pediatric International 28% deficient, 16% severe Association with breast feeding was found National micronutrient survey 2010 women deficient < 12 ng/ml > 50% children 1-6 yrs< 11 ng/ml 10-20% Takruri, Khuri-Bulos et al , JMJ, 1-6 yrs also 30% insufficient

Study on newborn and pregnant mothers and vitamin D Ongoing study of vitamin D in newborn More than 3000 vitamin D levels obtained in the first day of life Range from 0.1- 15 ng/ml Cut off for this is 20 ng/ml 99.8 were vitamin D deficient below 10 ng/ml Mean was 3 ng/ml !!! 100 Mothers who were tested also had decreased vitamin D level. Almost uniformly less than 10ng/ml

Vitamin D levels in newborns in Jordan Overwhelming majority >99% are deficient < 15 nanograms/ml

What should be done Increased sun exposure, not consistent with current social norms Supplementation of the different age groups Fortification of food items, most useful Which food item?? Oil preferable but flour more feasible since it is cheaper and is the main staple food For infants must give vitamin d drops Pregnant women should be studied further and supplementation during pregnancy must be done

Thank you

Vitamin D activity Activated T lymphocytes and macrophages have increased VDR This stimulates antibody mediated and phagocyte mediated cytotoxicity Clinical association with asthma and RSV if cord blood vitamin D is deficient Increased risk of cesarian section also with vitamin D deficiency

Metabolism of 25-Hydroxyvitamin D to 1,25-Dihydroxyvitamin D for Nonskeletal Functions. Figure 2. Metabolism of 25-Hydroxyvitamin D to 1,25-Dihydroxyvitamin D for Nonskeletal Functions. When a macrophage or monocyte is stimulated through its toll-like receptor 2/1 (TLR2/1) by an infectious agent such as Mycobacterium tuberculosis or its lipopolysaccharide, the signal up-regulates the expression of vitamin D receptor (VDR) and 25-hydroxyvitamin D-1α-hydroxylase (1-OHase). A 25-hydroxyvitamin D [25(OH)D] level of 30 ng per milliliter (75 nmol per liter) or higher provides adequate substrate for 1-OHase to convert 25(OH)D to its active form, 1,25 dihydroxyvitamin D [1,25(OH)2D]. 1,25(OH)2D travels to the nucleus, where it increases the expression of cathelicidin, a peptide capable of promoting innate immunity and inducing the destruction of infectious agents such as M. tuberculosis. It is also likely that the 1,25(OH)2D produced in monocytes or macrophages is released to act locally on activated T lymphocytes, which regulate cytokine synthesis, and activated B lymphocytes, which regulate immunoglobulin synthesis. When the 25(OH)D level is approximately 30 ng per milliliter, the risk of many common cancers is reduced. It is believed that the local production of 1,25(OH)2D in the breast, colon, prostate, and other tissues regulates a variety of genes that control proliferation, including p21 and p27, as well as genes that inhibit angiogenesis and induce differentiation and apoptosis. Once 1,25(OH)2D completes the task of maintaining normal cellular proliferation and differentiation, it induces expression of the enzyme 25-hydroxyvitamin D-24-hydroxylase (24-OHase), which enhances the catabolism of 1,25(OH)2D to the biologically inert calcitroic acid. Thus, locally produced 1,25(OH)2D does not enter the circulation and has no influence on calcium metabolism. The parathyroid glands have 1-OHase activity, and the local production of 1,25(OH)2D inhibits the expression and synthesis of parathyroid hormone. The 1,25(OH)2D produced in the kidney enters the circulation and can down-regulate renin production in the kidney and stimulate insulin secretion in the beta islet cells of the pancreas. Holick MF. N Engl J Med 2007;357:266-281.

Synthesis and Metabolism of Vitamin D in the Regulation of Calcium, Phosphorus, and Bone Metabolism. Figure 1. Synthesis and Metabolism of Vitamin D in the Regulation of Calcium, Phosphorus, and Bone Metabolism. During exposure to solar ultraviolet B (UVB) radiation, 7-dehydrocholesterol in the skin is converted to previtamin D3, which is immediately converted to vitamin D3 in a heat-dependent process. Excessive exposure to sunlight degrades previtamin D3 and vitamin D3 into inactive photoproducts. Vitamin D2 and vitamin D3 from dietary sources are incorporated into chylomicrons and transported by the lymphatic system into the venous circulation. Vitamin D (hereafter “D” represents D2 or D3) made in the skin or ingested in the diet can be stored in and then released from fat cells. Vitamin D in the circulation is bound to the vitamin D–binding protein, which transports it to the liver, where vitamin D is converted by vitamin D-25-hydroxylase to 25-hydroxyvitamin D [25(OH)D]. This is the major circulating form of vitamin D that is used by clinicians to determine vitamin D status. (Although most laboratories report the normal range to be 20 to 100 ng per milliliter [50 to 250 nmol per liter], the preferred range is 30 to 60 ng per milliliter [75 to 150 nmol per liter].) This form of vitamin D is biologically inactive and must be converted in the kidneys by 25-hydroxyvitamin D-1α-hydroxylase (1-OHase) to the biologically active form — 1,25-dihydroxyvitamin D [1,25(OH)2D]. Serum phosphorus, calcium, fibroblast growth factor 23 (FGF-23), and other factors can either increase (+) or decrease (–) the renal production of 1,25(OH)2D. 1,25(OH)2D decreases its own synthesis through negative feedback and decreases the synthesis and secretion of parathyroid hormone by the parathyroid glands. 1,25(OH)2D increases the expression of 25-hydroxyvitamin D-24-hydroxylase (24-OHase) to catabolize 1,25(OH)2D to the water-soluble, biologically inactive calcitroic acid, which is excreted in the bile. 1,25(OH)2D enhances intestinal calcium absorption in the small intestine by interacting with the vitamin D receptor–retinoic acid x-receptor complex (VDR-RXR) to enhance the expression of the epithelial calcium channel (transient receptor potential cation channel, subfamily V, member 6 [TRPV6]) and calbindin 9K, a calcium-binding protein (CaBP). 1,25(OH)2D is recognized by its receptor in osteoblasts, causing an increase in the expression of the receptor activator of nuclear factor-κB ligand (RANKL). RANK, the receptor for RANKL on preosteoclasts, binds RANKL, which induces preosteoclasts to become mature osteoclasts. Mature osteoclasts remove calcium and phosphorus from the bone, maintaining calcium and phosphorus levels in the blood. Adequate calcium (Ca2+) and phosphorus (HPO4 2−) levels promote the mineralization of the skeleton. Holick MF. N Engl J Med 2007;357:266-281.

The immune system and Vitamin D Calcitriol (I,25, OH) has immune modulating function First described with sarcoidosis Calcitriol produced by macrophages in the granulomas lead to hypercalcemia Calcitriol also inhibits proliferation of MTB in cells This is not subject to feedback as is the kidney Vitamin D deficiency has been shown to increase the risk of infection especially respiratory infection

Vitamin D functions Vitamin D has other roles in the body, including modulation of cell growth, neuromuscular and immune function, and reduction of inflammation Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by vitamin D Serum concentration of 25(OH)D is the best indicator of vitamin D status. It reflects vitamin D produced cutaneously and that obtained from food and supplements and has a fairly long circulating half-life of 15 days

Sun exposure and vitamin D Complete cloud reduces UV energy by 50%; shade UVB radiation does not penetrate glass, so exposure to sunshine indoors through a window does not produce vitamin D Sunscreens with a sun protection factor (SPF) of 8 or more appear to block vitamin D-producing UV rays