Table 2.
Study characteristics of studies of rickets in young children
| Study ID* | Country | Study design | Participant description | Vitamin D assay |
|---|---|---|---|---|
| Acoglu 2020 [40] | Turkey | Cross-sectional study | 77 Syrian and Iraqi refugee children, 1–24 months old (mean 11 months), who presented at the hospital for various reasons. Rickets definition: Inadequate vitamin D (< 12 ng/mL) and/or calcium with elevated ALP and PTH and radiological findings of rickets. | NR |
| Aggarwal 2012 [35] | India | Case–control study | 135 children, 0.5–5 years old (mean 13 months), with nutritional rickets (n = 67) and age- and sex-matched healthy controls (n = 68), 40% breastfed. Excluded children with non-nutritional rickets, hypocalcemic seizures, consuming calcium or vitamin D supplements in the past 6 months. | Electrochemiluminescence immunoassay (Cobas) |
| Aggarwal 2013 [36] | India | Trial | 67 children, 0.5–5 years old (mean 18 months), with nutritional rickets. Excluded children with features suggestive of non-nutritional etiology, hypocalcemic seizures, or consumption of calcium or vitamin D supplements in the past 6 months. This study did not report serum 25OHD at baseline. | Electrochemiluminescence immunoassay (Cobas) |
| Ahmed 2020 [37] | Bangladesh | Case–control study | 48 children, 1.0–10.9 years old (mean 3 years), with active rickets (n = 24) and their controls (n = 24) matched for age, sex and village. Excluded those who took medication or dietary supplements that could affect bone metabolism, with renal or intestinal disease, physical disability or impaired mobility. | Chemiluminescence immunoassay (Liaison, Diasorin), participating in the Vitamin D Standardization Program (VDSP) |
| Al-Atawi 2009 [51] | Saudi Arabia | Case series | 283 Saudi infants, 6–14 months old (mean 9 months), with nutritional rickets, 70% exclusively breastfed with no supplementation, seen at the hospital over a 10-year period. Excluded children with liver disease, renal disease, hypoparathyroidism, taking anti-convulsion medication, and with non-nutritional rickets. | NR |
| Alouf 2005 [52] | USA | Case report | One female, 3.5 months old, born at term, African-American. | NR |
| Amirlak 2008 [53] | United Arab Emirates | Case report | Two infants, 9 months old, exclusively breastfed, with rickets. | NR |
| Arnaud 1976 [54] | Canada and USA | Case–control study | 7 infants 2–42 months old (mean 1.7 years old) with nutritional deficiency rickets and 9 control children (mean 2.7 years old) followed in the outpatient clinics for well-baby care or problems unrelated to skeletal disease. | Radioimmunoassay |
| Ashraf 2002 [55] | UK | Case series | 3 children, 8, 9 and 15 months old, with (n = 2) and without (n = 1) radiological features of rickets, South East Asian ethnicity. | NR |
| Balasubramanian 2003 [38] | India | Case–control study | 58 children, 0.5–10 years (mean 29 months), with rickets (n = 24) and controls (n = 34) attending the pediatrics department for acute illnesses (e.g. upper respiratory tract infection). | Radioimmunoassay (DiaSorin) |
| Balkan 2005 [56] | Turkey | Case report | One male, 6 months old, exclusively breastfed, no vitamin D supplementation. | NR |
| Baroncelli 2008 [25] | Egypt and Turkey | Case–control study | 148 children, 0.5–4 years old, from hospitals with rickets (n = 98) and non-rachitic controls (siblings or children with minor illnesses such as upper respiratory infections) (n = 50), 10–70% breastfed. Excluded prematurity, renal, liver, intestinal, cardiac or central nervous system disease, chronic diseases, tuberculosis, and hereditary forms of rickets. | Competitive binding RIA (DiaSorin) |
| Beck-Nielsen 2009 [57] | Denmark | Case series | 41 children, 4–19 months (median 11–14 months), with rickets, with (n = 15) and without (n = 26) seizures, approximately 50% Ethnic Danish, 49% breastfed or weaned within 6 months before diagnosis of rickets, 24% on milk-free diet. Excluded children with serum 25OHD ≥ 50 nmol/L. | NR |
| Bereket 2010 [58] | Turkey | Case series | 22 children, 0.2–3 years (mean 1.3 years), with rickets. Excluded prematurity, renal, liver or intestinal disease. | Chemiluminescence immunoassay (Nichols Advantage competitive binding assay) |
| Betend 1981 [59] | France | Case report | One male, 4 months old, term, healthy, fed with evaporated cow milk, no vitamin D supplement. | NR |
| Bhimma 1995 [60] | South Africa | Case series | 7 children, 1–3 years old (mean 2 years), dark skin, with no vitamin D or calcium supplementation, with vitamin D deficiency rickets (n = 3), with calcium deficiency rickets (n = 3), and with healing or healed rickets (n = 1). Excluded gastro-intestinal, hepatic and renal glomerular causes of rickets. | Competitive binding assay |
| Blok 2000 [61] | New Zealand | Case series | 18 children, 3–26 months old (median 12 months, mean 14 months), with vitamin D deficient rickets (serum 25OHD < 10 µg/L and radiological evidence of rickets), 66% of Indian ethnic origin. | NR |
| Blond 1997 [62] | France | Case report | One infant, 3 days old, dark skin. | NR |
| Bloom 2004 [63] | USA | Case report | One female and one male, 15 and 16 months old, with dark skin, no dairy intake, with rickets. | NR |
| Brinsmead 2011 [64] | Australia | Case report | One female, 12 months old, Indian ethnicity, was born at term. | NR |
| Chatterjee 2017 [65] | India | Case series | 191 children, 0.5–9 years, with nutritional rickets. Excluded prematurity, renal or hepatic disease, intestinal malabsorption, tumor, chronic diseases, tuberculosis, diseases of the skeletal system, hypophosphatemic rickets, phosphaturia, and vitamin D-dependent rickets types 1 and 2. | Chemiluminescence micropartical immunoassay (CMIA) |
| Chehade 2011 [66] | Switzerland | Case report | One infant, 16 months old, dark skin, breastfed, without vitamin D supplementation, little dairy intake. | NR |
| Chuang 2018 [67] | Taiwan | Case series | 8 children, 12–25 months (mean 20 months), with nutritional rickets, 80% with a special diet. Excluded those with rickets of causes other than nutritional, major systematic disease or taking anti-convulsant therapy. | Radioimmunoassay (Diasorin) |
| Curtis 1983 [68] | Canada | Case report | 3 children, 1.5, 2.75 and 3.5 years old, dark skin, breastfed, vegetarian diet, no vitamin supplements. | NR |
| Dabas 2022 [26] | India | Trial | 132 children, 0.5–12 years, with nutritional rickets. Excluded malabsorption, chronic kidney or hepatic disease, systemic illness or vitamin D or calcium supplement in the past 6 months. | Electrochemiluminescence immunoassay autoanalyzer (Roche Cobas e411) |
| Dawodu 2006 [69] | United Arab Emirates | Case series | 40 children, 2–30 months (median 14 months), Arab origin, with vitamin D deficiency rickets. Excluded rickets due to malabsorption, renal or liver diseases, inherited disorders such as vitamin D-dependent rickets. | NR |
| DeLucia 2003 [70] | USA | Case series | 143 children, 4–38 months old (mean 20.2 months), with nutritional rickets, 79% African-American, 96% history of breastfeeding, and 15% vitamin D supplementation. Three cases, 24, 24 and 9 months old, dark skin, and no vitamin D supplementation, were also presented in detail. Excluded nutritional deficiency secondary to another disease and rickets secondary to genetic or other non-nutritional etiologies. | Competitive binding assay |
| Duplechin 1999 [71] | USA | Case report | One female, 17 months old, dark skin, breastfed, described as “picky eater”. | NR |
| El Kholy 2017 [27] | Egypt | Case–control study | 109 rachitic children and 30 controls (siblings or children with minor illnesses), 7 months—3 years (mean 18 months). Excluded vitamin D or calcium supplementation prior to 6 months, kidney disease, tuberculosis, liver disease, prematurity, intestinal, cardiac, central nervous system or other chronic disease, other bone disease, hereditary rickets, or low weight for height. | Immunoassay (Immunodiagnostik) |
| Elidrissy 1984 [72] | Saudi Arabia | Case–control study | 51 children, 4–26 months old (mean 10.5 months), 92% breastfed, with active rickets (n = 16), healing rickets (n = 18) and no rickets (n = 17). | Competitive binding assay |
| Elidrissy 2012 [73] | Saudi Arabia | Case series | 136 children with active rickets (n = 86, mean age 17 months) and healed rickets (n = 50, mean age 23.9 months). | NR |
| Elzouki 1989 [74] | Libya | Case series | 16 children, 3–24 months (mean 15 months), treated for rickets at the hospital. Majority of the children were breastfed, infrequently exposed to sunshine, veiled mothers, malnourished. None had malabsorption. | UV absorptiometry and competitive protein binding assay |
| Eren 2015 [75] | Turkey | Case report | One male, 3 months old. | NR |
| Estrade 2017 [76] | France | Case report | One male, 2 years old, no vitamin D supplementation and his older brother, 3.2 years, and younger sister, 0.7 years, dark skin. | NR |
| Eugster 1996 [77] | USA | Case series | 7 children, 6–20 months old (mean 10 months), 57% dark skin, with (n = 6) and without (n = 1) radiologically confirmed rickets. | NR |
| Fidan 2017 [78] | Turkey | Case series | 26 children, 3–30 months old (mean 8.6 months), well-nourished | NR |
| Flot 2020 [79] | France | Case series | 38 children, 0.3–12.0 years (median 1.9 years), 78% exclusively breastfed, with (n = 8) and without (n = 30) seizures, 50% Sub-Saharan African, 34% North Africa and Middle East, 11% Europe, 5% South Asia. | NR |
| Gad 2014 [80] | UK | Case report | One female, 7 months old, dark skin, seizures, exclusively breastfed, no supplementation. | NR |
| Garabedian 1983 [81] | Belgium and France | Case series | 20 children, 4 months—12 years old (75% 4–26 months old), 80% immigrants, no anticonvulsant therapy. | Competitive binding assay |
| Ginat-Israeli 2003 [82] | Israel | Case report | One male, 2 years old, ate only a peanut snack and artificial raspberry juice, and female, 7 months old, fed diluted cow milk. Both are from Ethiopia. | NR |
| Graff 2004 [28] | Nigeria | Case–control study | 15 children, 2–8 years old (mean 46 months), with rickets and age- and 15 sex-matched control children (mean 47 months old). Excluded renal or liver disease, tuberculosis, chronic diarrhea, use of phenytoin, calcium or vitamin D supplements in the past 4 weeks. | Competitive binding assay |
| Hoecker 2002 [83] | USA | Case report | One male, 13 months old, dark skin, breastfed, no intake of soy, dairy or eggs. | NR |
| Holick 2009 [84] | USA | Case report | One male, 9 months old, African American, breastfed, no vitamin supplementation. | NR |
| Jain 2011 [41] | India | Cohort study | 98 infants, 2.5–3.5 months old (mean 3.1 months), term, AGA, 71% exclusively breastfed. | Radioimmunoassay (DiaSorin) |
| Jones 2018 [29] | Kenya | Case–control study | 21 children, 3–24 months old (mean 12 months old), with rickets, and 22 controls without rickets or acute malnutrition. Excluded emergency medical care, tuberculosis, facture in past 3 months, HIV infection or exposure. | Radioimmunoassay (DiaSorin) |
| Khan 2020 [85] | Pakistan | Trial | 198 children, 0.5–3 years (mean 13 months), with rickets. Excluded non-nutritional rickets, congenital anomalies, kidney or liver disease, malabsorption, antiepileptics, and history of vitamin D megadose. | NR |
| Koseick 2007 [86] | Turkey | Case report | One male, 14 months old, breastfed, no supplementation. | NR |
| Kreiter 2000 [87] | USA | Case series | 23 children, 5–24 months (mean 14 months), African American, breastfed. | NR |
| Kruse 2000 [88] | Germany | Case series | 115 children, 1 month—4.2 years old (median 13 months), with vitamin D deficiency rickets, 63% immigrants. | NR |
| Kubota 2006 [89] | Japan | Case series | One female, 19 months old, and one male, 29 months old, with rickets, both breastfed, male no diary intake. | NR |
| Ladhani 2004 [90] | UK | Case series | 65 children, 0–13 years old (mean 2.6 years), with vitamin D deficiency rickets (25OHD < 25 nmol/L and radiologically confirmed rickets), 60% Asian, 37% Afro-Caribbean, 3% European, with (n = 29) or without (n = 36) hypocalcemic symptoms. | Radioimmunoassay (ImmunoDiagnostic) |
| Lautatzis 2019 [91] | Canada | Case series | 114 children, 0–16 years (median 30 months), with nutritional rickets (n = 46) or vitamin D deficiency (n = 68). Children with 25OHD < 30 nmol/L had radiography. | LC–MS/MS or radioimmunoassay (Diasorin) |
| Lazol 2008 [42] | USA | Case series | 58 children, 2–132 months old (mean 18 months), with nutritional rickets, 96% born full-term, 81% African Americans, 14% Arabic, 3% Hispanic, 2% Caucasian, 96% breastfed, no vitamin supplements. | NR |
| Lemoine 2020 [92] | France | Case report | One infant, 13 months old, Eurasian, breastfed, vegan diet, no vitamin D supplementation. | NR |
| Lin 2020 [93] | USA | Case report | One female, 6 months old, formula-fed. | NR |
| Machiels 1995 [94] | Belgium | Case report | One female, 13 months old, no dairy intake. | NR |
| Markestad 1984 [95] | Norway | Cohort study | 7 infants followed at 3, 5, and 12 months of age. | Radioimmunoassay |
| Meyer 2017 [96] | Norway | Case series | 37 children, 0.1–3.5 years (mean 1.4 years), with nutritional rickets (25OHD < 12.5 nmol/L or 25OHD 12.5–25 nmol/L and elevated alkaline phosphatase or PTH or low serum calcium or 25OHD 25–37 nmol/L with rickets in x-ray), 93% non-Western immigrant background. | NR |
| Mittal 2014 [97] | India | Trial | 76 children, 0.5–5 years old (median 12 months), with rickets. Excluded malabsorption, liver or renal insufficiency, hypercalcemia, history of vitamin D, calcium or medication affecting vitamin D metabolism in the past 6 months. | Radioimmunoassay (DiaSorin) |
| Mittal 2019 [98] | India | Trial | 86 children, 0.5–5 years old (median 10.5 months), with rickets. Excluded malabsorption, steroids, antitubercular or antiepileptic drugs, history of vitamin D, calcium or medication affecting vitamin D metabolism in the past 6 months or non-nutritional rickets. | Radioimmunoassay (DiaSorin), participating in the Vitamin D External Quality Assessment Scheme (DEQAS) |
| Molla 2000 [99] | Kuwait | Case–control study | 103 children with rickets (mean age 14 ± SD 5 months) and 102 age- and socioethnic-matched controls (mean age 15 ± SD 6 months). | Radioimmunoassay |
| Moncrieff 1974 [100] | UK | Case report | One female, 4 days old, born at term, Asian ethnicity. | NR |
| Mondal 2014 [101] | India | Trial | 61 children, 0.5–5 years old (mean 13 months), with rickets. Excluded non-nutritional rickets, vitamin D or calcium in the past 6 months. | Radioimmunoassay (DiaSorin) |
| Mughal 1999 [102] | UK | Case report | 6 children, 10–28 months old (mean 18 months), with rickets, breastfed exclusively or prolonged periods of time, no vitamin D supplementation, dark-intermediate skin. | NR |
| Mustafa 1999 [103] | Canada | Case report | One male, 5 months old, breastfed, no supplement, dark skin. | NR |
| Naik 2017 [45] | India | Trial | 110 children, 6 months old, whose mother received (n = 53) or not (n = 57) vitamin D supplementation during post-partum, breastfed. | Radioimmunoassay (DiaSorin) |
| Oginni 1996 [104] | Nigeria | Case–control study | 26 children, 1–5 years old, with rickets and healthy controls. | Radioimmunoassay (ImmunoDiagnostic) |
| Oginni 2003 [105] | Nigeria | Case series | 26 children, 2–5 years (mean 3.1 years), with rickets. | Radioimmunoassay (Incstar) |
| Ojeda 2010 [106] | Spain | Case report | One female, 5 months old, breastfed, dark skin. | NR |
| Olgun 2003 [107] | Turkey | Case report | One female, 9 months old. | NR |
| Oramasionwu 2008 [30] | Nigeria | Case series | 12 children, 2–14 years old (mean 38 months). | NR |
| Orbak 2005 [108] | Turkey | Case series | 42 infants, 1–3 months (mean 2 months), 83% exclusively breastfed. | Radioimmunoassay (Biosource) |
| Ozkan 2009a [109] | Turkey | Case–control study | 39 children, 0–36 months old (mean 10 months), with vitamin D deficiency rickets and 15 controls. | Competitive binding RIA (Immunodiagnostic Systems) |
| Ozkan 2009b [110] | Turkey | Trial | 21 children, 2–16 months old (mean 7 months), with vitamin D deficiency rickets. Excluded children with familial rickets, kidney, liver and gastrointestinal system diseases. | Competitive binding RIA |
| Pearson 2010 [111] | USA | Case report | One male, 16 month-old, breastfed up to 12-month-old, Hispanic, with cow milk allergy, fed rice milk. | NR |
| Pedersen 2003 [112] | Denmark | Case series | 31 children, 0.5–4 years (mean 1.7 years), 100% immigrants. | NR |
| Pedrosa 2013 [113] | Portugal | Case report | One female and three males, 4 months, 8 days, 9 months and 4 months old, breastfed, no supplements, dark skin. | NR |
| Perez-Rossello 2012 [114] | USA | Case–control study | 36 children, 8–24 months old (mean 11.4 months), with vitamin D deficiency (25OHD ≤ 20 ng/mL) with (n = 2) or without (n = 34) rachitic changes in x-ray. Excluded chronic disease, oral glucocorticoids, anticonvulsants, or other medications affecting vitamin D metabolism in the past 3 months. Rickets definition: 25OHD ≤ 20 ng/mL and radiologically rachitic changes. | Radioimmunoassay (DiaSorin) |
| Pietrek 1980 [115] | Poland | Case–control study | 213 infants, 2–24 months old, healthy (n = 90) or hospitalized (n = 123). | Radiocompetitive assay |
| Prentice 2008 [116] | Gambia | Case–control study | 193 children 1.1–16.4 years (mean 43 months old), with active rickets (n = 13) and non-active rickets (n = 33) and community controls (n = 147). | Radioimmunoassay (DiaSorin) |
| Rajah 2008 [117] | United Arab Emirates | Trial | 16 children, 6–48 months (mean 17 months), with nutritional rickets with vitamin D deficiency (n = 8) or calcium deficiency (n = 8). Excluded hypocalcemia-related tetany/seizures. | Chemiluminescence immunoassay (Nichols Advantage system) |
| Rajah 2010 [118] | United Arab Emirates | Trial | 10 children, 11–39 months old (mean 21 months), with rickets. Excluded renal or liver disease, antiepileptic medication, vitamin D dependent or hypophosphatemic rickets. | HPLC |
| Ramavat 1999 [119] | Kuwait | Case series | 14 newborns, within 24h of birth, born with rachitic rosary and with rickets radiologically confirmed by wrist x-ray | Radioimmunoassay |
| Robinson 2006 [120] | Australia | Case series | 126 children, 0–15 years (median age 15.1 months), with rickets, 71% breastfed, 4% White, hypocalcemia (n = 65) or normocalcemia (n = 61). | Competitive binding assay |
| Sakamoto 2018 [121] | Japan | Case series | Two patients, 12–26 months old, with nutritional rickets. | Radioimmunoassay |
| Salama 2010 [122] | Egypt | Case series | 32 infants, 3–18 months (mean 8 months), breastfed, not receiving supplements, with rickets. | NR |
| Saluja 2021 [123] | India | Trial | 66 children, 9–60 months old (mean 21 months), with rickets, 95% breastfed, 51% hypocalcemia. Excluded ill, malabsorption disorders, liver or renal insufficiency, hypercalcemia, history of vitamin D, calcium supplements or drugs affecting vitamin D metabolism in past 6 months. | Radioimmunoassay (Beckman Coulter India) |
| Shah 1994 [43] | USA | Case series | 42 children, 5–109 months old (median 16 months), with nutritional rickets, 2 received ant-convulsant therapy and 18 followed a vegan or non-dairy diet. | NR |
| Shah 2000 [124] | USA | Case series | 9 children, 8–23 months old (mean 16 months), with nutritional rickets. | NR |
| Shaikh 2006 [125] | USA | Case series | 5 children, 7–24 months old (mean 16 months), with vitamin D deficiency rickets, dark skin, breastfed, no supplement, described as "picky eater". Excluded prematurity, chronic renal disease, familial hypophosphatemia, hypocalcemia, congenital and genetic abnormalities. | NR |
| Sodri 2021 [126] | Malaysia | Case report | One female, 22 months old, little sun exposure. | NR |
| Soliman 2008 [127] | Qatar | Case series | 46 children, up to 3 years old (mean 13 months), with nutritional rickets (i.e. low serum 25OHD, elevated ALP, normal or low Ca, normal or low PO4, high PTH, radiological confirmation of rickets). Excluded children with heritable disorders of vitamin D metabolism. | NR |
| Soliman 2010 [128] | Qatar | Case series | 40 children, up to 3 years old (mean 16 months), with rickets. Excluded malabsorption, liver disease, renal insufficiency, malnutrition, parenteral nutrition, vitamin D deficiency secondary to congenital disorder of vitamin D metabolism. | Radioimmunoassay (Mediagnost) |
| Specker 1992 [47] | China | Trial | 256 term infants born in Spring or Fall in a Northern or Southern city at 3–5 days of age and at 6 months of age, randomized to vitamin D supplementation (100, 200 or 400 IU/d). | Radioimmunoassay |
| Spence 2004 [129] | USA | Case report | One male, 9 months old, African American, breastfed, no vitamin supplementation. | NR |
| Stevens 2009 [130] | USA | Case report | One male, 6 months old, African American, exclusively breastfed. | NR |
| Thacher 1997 [39] | Nigeria | Case–control study | 37 children, 9 months—8 years (mean 3.2 years), with active rickets, only 7% were severely malnourished, no seizures, and 37 age-matched healthy controls, recovered from acute illness with normal weight. Excluded chronic diarrhea, signs of liver or renal disease or on anticonvulsant therapy. | Radioimmunoassay |
| Thacher 1999 [131] | Nigeria | Trial | 123 children, 1–14 years old (median 46 months), with active rickets. Excluded vitamin D or calcium supplement in past 12 weeks, renal disease, tuberculosis, liver disease. | Radioimmunoassay |
| Thacher 2000 [31] | Nigeria | Case–control study | 246 children, 1–14 years old (median 44 months), with active rickets (n = 123) and controls (n = 123). Excluded vitamin D or calcium supplement in past 12 weeks, renal disease, tuberculosis, liver disease. | Radioimmunoassay |
| Thacher 2006 [132] | Nigeria | Case series | 16 children, 15–48 months old (mean 31 months), with active rickets. | Radioimmunoassay (DiaSorin) |
| Thacher 2009a [32] | Nigeria | Trial | 17 children, 28–118 months old (mean 44.5 months), with nutritional rickets. | LC–MS/MS (API 4000) |
| Thacher 2009b [33] | Nigeria | Case–control study | 19 children, 2–10 years old, with rickets and 15 age-matched controls. | Radioimmunoassay (DiaSorin) |
| Thacher 2010 [133] | Nigeria | Case–control study | 49 children, 15–120 months old (mean 43 months), with rickets (n = 28) or healthy controls (n = 21). | Radioimmunoassay (DiaSorin) |
| Thacher 2012 [134] | Nigeria | Trial | 4 children (4 out of 647), 12–18 months old (mean 14.8 months), who had radiologically active rickets after 18 months intervention (calcium + vitamin A, ground fish + vitamin A or vitamin A alone). | Radioimmunoassay (DiaSorin) |
| Thacher 2013 [135] | USA | Case series | 17 children, 5–27 months old (mean 13 months), with nutritional rickets. | NR |
| Thacher 2014 [34] | Nigeria | Trial | 37 children 1–3 years old, with active rickets (radiographic score of at least 2.5). Note: Only the children below 4 years of age were included. | LC–MS/MS |
| Thacher 2015 [136] | Nigeria | Trial | 88 children, 6–151 months (median 35 months), with active rickets. Excluded vitamin D or calcium supplement in the past 4 weeks. | LC–MS/MS |
| Train 1995 [137] | UK | Case report | One male, 5 months old, black. | NR |
| Trivedi 2020 [46] | India | Trial | 114 children, at 6 months old, exclusively breastfed, from mothers given vitamin D3 supplements (4 × 60,000 IU) or placebo. | Chemiluminescence immunoassay (CLIA) (Access2 Beckman Coulter) |
| Uday 2018 [138] | UK | Case series | Three children of 5, 6, and 6 months old, exclusively breastfed, dark skin, with rickets. | NR |
| Valerio 2015 [139] | Portugal | Case report | One male, 28 months old, dark skin, breastfed, no dairy intake, no supplementation. | NR |
| Vanstone 2012 [140] | USA | Case report | One male 4 months old and a female 2 years old, both dark skin and breastfed. | NR |
| Vierucci 2017 [141] | Italy | Case report | One male, 10 month old, dark skin. | Radioimmunoassay (DiaSorin) |
| Vuletic 2016 [142] | Serbia | Case report | One male, 5 months old, not breastfed, no vitamin D supplement. | NR |
| Walter 2010 [143] | Spain | Case report | Two males, 6 and 7 months, of North Africa and Asia origin, breastfed. | NR |
| Weinstein 2003 [144] | USA | Case report | One male, 20 months old, dark skin, soy-based milk, no vitamin D supplementation. | NR |
| Wheeler 2015 [44] | New Zealand | Case series | 58 children, 0.3–11 years old (median 1.4 years), with vitamin D deficiency rickets (25OHD < 50 nmol/L, elevated ALP and/or radiological rickets—77.4% with radiological changes), 87% born at full-term, 50% dark skin, 31% intermediate skin, and 19% fair skin, 93% history of exclusive breastfeeding, 9% vitamin D supplementation. Excluded chronic disease, fat malabsorption, liver disease, renal insufficiency, genetic forms of rickets, and parenteral nutrition. | NR |
| Williams 2008 [145] | USA | Case report | One female, 11 months old, African, breastfed, no intake of milk, no vitamins. | Radioimmunoassay (DiaSorin) |
| Yener 1995 [146] | Turkey | Case–control study | 16 children, 7–24 months (mean 14.9 months), with rickets, breastfed during first months, well-nourished, but inadequate vitamin D intake (12 with infection on admission) and 15 controls, 6–24 months (mean 15.8 months), healthy (10 with infections). | Radioimmunoassay (Incstar, Stillwater) |
| Yu 2006 [147] | Canada | Case report | One male, 2-year-old, Inuit, no dairy, soy milk. | NR |
Notes: NR: Not reported
*Studies in bold reported calcium intake