Vitamin D Deficiency Clinical Trial
Official title:
Vitamin D Deficiency, Iodine Deficiency and Lead Levels in Haitian Infants and Children.
Vitamin D deficiency is common worldwide, including in infants and children, and rickets
remains a public health concern in many developing countries. The vitamin D status and
prevalence of vitamin D deficiency in the Haitian population has not been studied. There is
currently no approved point-of-care testing device for vitamin D deficiency. Iodine
deficiency and resulting hypothyroidism is the leading cause of preventable
neuro-developmental delay and cognitive impairment worldwide. Young infants and children are
especially susceptible to sequelae of disruption in thyroid function given the dependence of
the developing brain on sufficient levels of thyroid hormone. Perchlorate and thiocyanate
have been described as potential environmental disrupters of thyroid function. Lead
intoxication is a significant cause of disease throughout the world. Millions of people have
suffered the effects of lead poisoning. Although most developed countries have taken drastic
measures to limit the environmental lead levels, many countries in the developing world have
not been able to address, or even assess, the problem.
Our objectives are to study the following three components in 300 Haitian children between 9
months and 6 years of age in three different geographical areas of Haiti: 1) Vitamin D
status and prevalence of rickets, environmental factors associated with low vitamin D
levels, and the accuracy and efficacy of a vitamin D point-of-care testing (POCT) device for
the screening of vitamin D insufficiency. 2) Iodine status and thyroid function, and
environmental disruptors such as perchlorate and thiocyanate as potential risk factors for
abnormal thyroid function. 3) Lead levels and the extent of childhood lead poisoning.
BACKGROUND:
1. Vitamin D Deficiency
Vitamin D deficiency is common in the United States and worldwide, including in infants
and children 1,2. Moderate to severe deficiency in children can manifest as rickets, a
skeletal disease which results from a failure of mineralization of developing bones and
cartilage. In most industrialized countries, infantile vitamin D supplementation
represents the standard of care and has lead to a dramatic reduction in the incidence
of rickets. However, in many developing countries, rickets remains a public health
problem 3.In addition, recent literature indicates that there may be a resurgence of
rickets even in industrialized countries 4, especially among immigrant populations 5.
Potential extraskeletal effects of vitamin D deficiency are also being increasingly
recognized, including an increased susceptibility to type 1 diabetes, insulin
resistance and the metabolic syndrome, pulmonary disease such as asthma, pneumonia and
tuberculosis, and possible modulation of the innate immune system 6.
Growing children with severe vitamin D deficiency, most commonly defined as serum
25-hydroxy-vitamin D (25OHD) levels less than 8 ng/ml, are at greatest risk for rickets
and should undergo a diagnostic evaluation. When physical exam findings such as bowing
of weight-bearing extremities, rachitic rosary, or frontal bossing are not evident, the
level of serum alkaline phosphatase as an indicator for increased bone turnover and
calcium mobilization from bone can be used as a screening test 4,7. X-rays of knees and
wrists are typically obtained to confirm the diagnosis and establish a baseline for
follow up.
The vitamin D status and prevalence of vitamin D deficiency in the Haitian population
has not been studied. The prevalence of rickets is also unknown. Two studies conducted
in Puerto Rican children 8 and in newly immigrated adults of Caribbean background 9
found prevalence rates of 47% and 59%, respectively, suggesting the possibility of
moderate to high prevalence rates in Haiti.
The best indicator to assess vitamin D status is the 25OHD metabolite, the major
circulating form of vitamin D 10. There is no international consensus on the definition
of vitamin D deficiency. The Institute of Medicine defines deficiency as a 25OHD <
20ng/mL and suggests levels be maintained above this threshold for healthy children and
adolescents 11. The Endocrine Society recommendations were aimed at children and adults
with chronic conditions placing them at risk for a low bone mass and/or vitamin D
deficiency, and recommend using a level below 30 ng/mL (80 nmol/L) to define
insufficiency and below 20 ng/mL (50 nmol/L) to define deficiency 6. The Endocrine
Society treatment guideline for vitamin D deficiency for children 0-18 years suggests
administering oral vitamin D3 2000 IU daily or 50,000 IU weekly for 6 weeks, followed
by an age-appropriate maintenance dose.
In resource limited settings, laboratory facilities for vitamin D testing are
frequently unavailable. A point-of-care testing method would greatly facilitate
screening for vitamin D deficiency and insufficiency. The test 4D is a novel
point-of-care test device that is not yet FDA licensed. Only manufacturer based
information on test accuracy are currently available. The device has not been tested in
children (package insert is attached to this protocol).
2. Iodine Deficiency
Iodine deficiency and resulting hypothyroidism is the leading cause of preventable
neuro-developmental delay and cognitive impairment worldwide. Young infants and
children are especially susceptible to sequelae of disruption in thyroid function given
the dependence of the developing brain on sufficient levels of thyroid hormone.
Urinary iodine has been established as the gold standard for the assessment of iodine
status12. Values of 100-199 mcg/L are considered optimal, whereas levels <100 mcg/L,
<50 mcg/dL and <20 mcg/dL define mild, moderate and severe iodine deficiency,
respectively. On the other hand, the risk of iodine induced hyperthyroidism increases
when levels rise to 200 mcg/dl and above, and risk of adverse health consequences
increases with levels exceeding 300 mcg/L12. Perchlorate and thiocyanate are
environmental chemicals known to inhibit the sodium-iodine symporter when administered
at pharmacologic doses. This leads to interference with normal thyroidal iodine uptake
and results in decreased thyroid hormone production13,14. Both chemicals do not undergo
significant metabolism and can be readily detected in the urine. The effect of
environmental exposure to either is thought to be dependent on adequate iodine, and
should thus be assessed concurrent with urinary iodine status14.
Studies assessing the iodine status in Haiti are few in number and have mainly included
school-age children and adults. Three studies in school-aged children conducted between
1996 and 2002 have found moderate to severe iodine deficiency, with urinary iodine
levels ranging between 38.8 and 43.4 mcg/dL15-17, regardless of whether children from
coastal15,16 or mountainous regions17 were surveyed. One study found elevated TSH
values >5 mU/L in 78.5% of participants15. A more recent study conducted in 2008
examined 88 subjects between ages 2 and 72 years, and found a similar median urinary
iodine concentration18. Overall, between 60 and over 90% of the Haitian population may
be iodine deficient17-19, with up to 20% falling into the range of severe deficiency18.
Based on WHO data from 2005 to 2006, only 3% of households are consuming adequately
iodized salt19. No studies have been conducted in infants and children under the age of
5 years..
The proposed study will be the first to assess the iodine status of Haitian infants and
young children. The study will be conducted in 3 different geographical areas of the
country, including an urban setting (Port-au-Prince), a mountainous region (Central
Plateau), and a coastal area (Saint Marc) in an attempt to differentiate between areas
where iodine deficiency is more likely (Central Plateau) from those were it is less
likely (Saint Marc). For the first time, urinary iodine concentration in young children
will be obtained along with a clinical goiter assessment, concentrations of urinary
perchlorate and thiocyanate, as well as thyroid function studies (thyroid stimulating
hormone and free thyroxine).
Confirmation of iodine deficiency may have significant public health implications for
one of the most vulnerable populations: infants and young children. Improving their
access to iodized salt and/or iodine supplementation could have a major impact on
reducing the number of children (and future adults) with hypothyroidism-related mental
retardation. The study results may raise awareness of medical providers with regards to
the problem of iodine deficiency and related hypothyroidism, and may provide an
incentive to test children for hypothyroidism. There may be other major clinical
implications, including the ability to detect and treat affected children, and improve
their prognosis with regards to cognitive impairment. On a larger scale, depending on
the magnitude of the problem, the study findings may underline the need to assess
iodine deficiency and hypothyroidism in even younger infants, including newborns.
Results may further obviate the need for a newborn screening program for hypothyroidism
in Haiti.
3. Lead Intoxication
Lead intoxication is a significant cause of disease throughout the world. Millions of people
have suffered the effects of lead poisoning. Although most developed countries have taken
drastic measures to limit the environmental lead levels, many countries in the developing
world have not been able to address, or even assess, the problem.
Lead poisoning is a medical condition caused by increased levels of lead in the body. Lead
is a highly toxic heavy metal environmental toxicant and nerve poison that can contribute to
the destruction of many developmental functions by interfering with a variety of body
processes. Due to its insidious nature, lead causes subtle and sometimes unnoticeable
effects in children. Even low levels of lead exposure among children can be associated with
developmental problems including impaired cognitive function, reduced intelligence, impaired
hearing, reduced stature or damage to the bone marrow 20,21. Lead poisoning can cause severe
toxicities including convulsions, coma, and death 22. In the United States, the Centers for
Disease Control and Prevention (CDC) define an elevated child BLL as ≥ 10 µg/dL. At this
BLL, the CDC has given permission to initiate public health actions. Additionally, the CDC
has also recommended that children with BLLs ≥ 45 µg/dL receive intensive medical management
and chelation therapy 23 to prevent irreversible damage to the child.
Among developing countries, major sources of childhood lead poisoning include lead mining
and smelting, paint, leaded gasoline, battery recycling, and traditional medicines 24,25
Despite the abundance of lead containing materials available in these developing countries,
there are still a limited number of studies that have actually documented environmental lead
contamination. Even with documented cases, information is further limited to adults living
in small-scale gold ore-processing communities 26-29. Despite the many advances of treatment
of lead poisoning in the US, there is still a paucity of information for childhood lead
poisoning in the developing world.
The proposed study will document lead levels in the pediatric population in three different
regions of Haiti. Data obtained from this study may lead to clinically relevant prognostic,
diagnostic or therapeutic modalities. This information may further be used to implement or
even eradicate lead as a public health hazard.
STUDY OBJECTIVES
Our objectives are to study the following three components in 300 Haitian children between 9
months and 6 years of age in three different geographical areas of Haiti: 1) Vitamin D
status and prevalence of rickets, environmental factors associated with low vitamin D
levels, and the accuracy and efficacy of a vitamin D point-of-care testing (POCT) device for
the screening of vitamin D insufficiency. 2) Iodine status and thyroid function, and
environmental disruptors such as perchlorate and thiocyanate as potential risk factors for
abnormal thyroid function. 3) Lead levels and the extent of childhood lead poisoning.
Aim 1: To determine the proportion of children with vitamin D insufficiency, deficiency and
severe deficiency, as defined by serum 25-hydroxyvitamin D (25OHD) levels <30ng/ml, <20
ng/ml, and <10 ng/ml, respectively.
Aim 2: To determine the proportion of children at high risk for rickets as defined by
vitamin D deficiency and elevations in alkaline phosphatase.
Aim 3: To determine the extent to which dietary vitamin D intake and sun exposure are
related to serum 25OHD levels.
Aim 4: To correlate the results from a vitamin D POCT device with serum 25OHD levels.
Aim 5: To determine the prevalence of iodine deficiency. Aim 6: To assess the subjects'
thyroid function (TSH and free T4). Aim 7: To screen for urinary presence of two potential
environmental disruptors of thyroid hormone production.
Aim 8: To determine the correlation of abnormal thyroid function, geographical area, and
presence of urinary perchlorate and thiocyanate with iodine status.
Aim 9: To determine the mean and range of blood lead levels (BLL). Aim 10: To determine the
proportion of children with a blood lead level (BLL) ≥ 10 µg/dL.
;
Observational Model: Ecologic or Community, Time Perspective: Cross-Sectional
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