Is iodine deficiency still a problem in sub-Saharan Africa?: a review

Factors associated with inadequate urinary iodine concentration among pregnant women in Mbeya region Tanzania

Background

Insufficient and above WHO-recommended levels of iodine intake during pregnancy can lead to serious health outcomes. This study aimed to assess median urine iodine concentration and its associated risk factors among pregnant women in the Mbeya region, Tanzania.

Method

A cross sectional survey involving 420 pregnant women (n=420) aged 15-49, registered in Reproductive and Child Health Clinics was conducted. Socio-demographic and dietary factors were assessed by structured questionnaire and the urine samples were analyzed using the ammonium persulfate digestion method.

Results

Median urinary iodine concentration (mUIC) was 279.4μg/L and it ranged from 26.1 to 1915μg/L. Insufficient mUIC (below 150μg/L) was observed in 17.14% of participants, sufficient mUIC was 24.29% and 58.57% had mUIC above the recommended level (>250μg/L). Sample women who reported consuming fish in the last 24 hours had an increased risk of insufficient mUIC [Adjusted OR= 2.60 (95%CI 1.31-5.15)] while the risk was lower for those who attended at least primary education [AOR= 0.29 (CI 0.08-0.99)]. Further, sample women resident in Mbarali district, in the oldest age group (35-49) and having a higher socio-economic status were associated with an increased risk of having MUIC above recommended level [AOR=4.09 (CI 1.85-9.010], [AOR=2.51 (CI 0.99-6.330] and, [AOR=2.08 (CI 0.91-4.71) respectively.

Conclusion

This study demonstrated a significant association between geographical, age and socio-economic factors and median urine iodine concentration above the WHO-recommended level. Further, this study found association between inadequate iodine in diet and insufficient median urine iodine concentration. Therefore, educational programs on iodine intake should be strengthened.

Changing trends in the global, regional, and national burden of iodine deficiency among adolescents and young adults: population-based study

Iodine is a micronutrient required for the production of thyroid hormones, which regulate metabolism, growth, and neurodevelopment. Iodine deficiency among adolescents and young adults is a major global health issue. We analyzed data from the Global Burden of Disease 2019 database to calculate the prevalence, incidence, and disability-adjusted life-year (DALY) rates of iodine deficiency among adolescents and young adults. We explored the specific year with the most substantial changes in the trends of iodine deficiency among adolescents with annual percentage change (APC) by Joinpoint Regression analysis. Descriptive analyses were conducted to characterize the iodine deficiency burden according to age, sex, location, and sociodemographic index (SDI) quintiles. All measures are listed with 95% uncertainty intervals (UIs), and all rates are reported per 100,000 individuals. From 1990 to 2019, the iodine deficiency prevalence rate among adolescents decreased from 3082.43 (95% uncertainty interval [UI], 2473.01-3855.86) to 2190.84 (95% [UI], 1729.18-2776.16) per 100,000 population, with an AAPC of -1.15 (95% confidence interval [CI], -1.29 to -1.02). Regarding the SDI in 2019, the highest prevalence and DALY rates of iodine deficiency were reported in low-SDI countries. In 1990, Southeast Asia had the highest prevalence and DALYs rates for iodine deficiency among adolescents, while in 2019, Africa had the highest prevalence rate (3330.12).

CONCLUSION

Globally, the iodine deficiency burden among adolescents has substantially decreased since 1990; however, low-SDI countries still bear a great burden. Implementation measures and monitoring systems should be strengthened to reduce the iodine deficiency burden, especially among adolescents.

WHAT IS KNOWN

• Iodine deficiency can cause severe or irreversible developmental disorders, particularly in adolescents and young adults. • Universal Salt Iodization was implemented for ensuring appropriate iodine intake.

WHAT IS NEW

• We found substantial declines in the prevalence rates of iodine deficiency among adolescents during the past three decades. Globally, the disability-adjusted life-year rate of iodine deficiency among adolescents decreased from 56.17 in 1990 to 35.38 in 2019. • Iodine deficiency among adolescents in low- sociodemographic index countries still bear a great burden.

Prevalence of Excessive Iodine Intake in Pregnancy and Its Health Consequences: Systematic Review and Meta-analysis

The objective was to estimate the prevalence of excessive iodine intake in pregnant women and to investigate the consequences for maternal-fetal health. The systematic review was based on PRISMA. The search was conducted in September 2021 in LILACS, PubMed/MEDLINE, Science Direct, and SCOPUS databases. Observational studies that assessed excessive nutritional iodine status in pregnancy diagnosed by urinary iodine concentration and associated it with biomarkers of thyroid health function were included. Study selection, data extraction, and risk of biased evaluation were performed independently. Meta-analysis was calculated using a fixed and random effect model, and heterogeneity was assessed by the chi-square test. Meta-regressions were performed to identify the causes of heterogeneity using the Knapp and Hartung test. Nine studies were included in the systematic review, and eight in the meta-analysis. The prevalence of excessive iodine intake in 10,736 pregnant women in different regions of the world was 52%. The main implications for pregnant women were hypothyroxinemia, hypothyroidism, and hyperthyroidism. For the newborn, macrosomia and thyroid dysfunction. In addition, drinking water with high iodine intake contributed to excessive iodine intake. Therefore, the prevalence of iodine excess was 52%, with high heterogeneity among studies, explained by trimester of gestation and FT4 level; therefore, the farther the trimester of gestation and the lower the FT4, the higher the prevalence of iodine excess. PROSPERO Registration: CRD420206467 ( https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=206467 ).

Adequacy of Iodine Status and Associations with Gut Health: A Prospective Cohort Study among Infants in 8 Low- and Middle-Income Countries

BACKGROUND

Environmental enteric dysfunction increases the likelihood of micronutrient deficiencies among infants, but few studies have assessed the potential impact of gut health on urinary iodine concentration (UIC) among this vulnerable group.

OBJECTIVES

We describe the trends of iodine status among infants from 6 to 24 mo old and examine the associations between intestinal permeability, inflammation, and UIC from 6 to 15 mo of age.

METHODS

Data from 1557 children enrolled in this birth cohort study conducted in 8 sites were included in these analyses. UIC was measured at 6, 15, and 24 mo of age by using the Sandell-Kolthoff technique. Gut inflammation and permeability were assessed using the concentrations of fecal neopterin (NEO), myeloperoxidase (MPO) and alpha-1-antitrypsin (AAT), and lactulose-mannitol ratio (LM). A multinomial regression analysis was used to assess the classified UIC (deficiency or excess). Linear mixed regression was used to test the effect of interactions among biomarkers on logUIC.

RESULTS

All studied populations had adequate (≥100 μg/L) to excess (≥371 μg/L) median UIC at 6 mo. Between 6 and 24 mo, 5 sites displayed a significant decline in the infant's median UIC. However, median UIC remained within the optimal range. An increase of NEO and MPO concentrations by +1 unit in ln scale reduced the risk of low UIC by 0.87 (95% CI: 0.78-0.97) and 0.86 (95% CI: 0.77-0.95), respectively. AAT moderated the association between NEO and UIC (P < 0.0001). The shape of this association appears to be asymmetric and in a reverse J-shape, with a higher UIC observed at both lower NEO and AAT concentrations.

CONCLUSIONS

Excess UIC was frequent at 6 mo and tended to normalize at 24 mo. Aspects of gut inflammation and increased permeability appear to reduce the prevalence of low UIC in children aged 6 to 15 mo. Programs addressing iodine-related health should consider the role of gut permeability in vulnerable individuals.

A systematic review and meta-analysis of the etiology and treatment patterns of thyrotoxicosis in Africa

INTRODUCTION

Thyrotoxicosis is one of the most common endocrine disorders seen in clinical practice. This study aims to determine the etiologies and treatment modalities of thyrotoxicosis in Africa.

AREAS COVERED

The study design is a systematic review with a meta-analysis. Medical databases and the gray literature were systematically searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies done in Africa on the etiology and treatment of thyrotoxicosis were selected.

EXPERT OPINION

In Africa, it is still believed that autoimmune diseases, generally, are not as common as what is seen in the western world. The frequency of Graves' disease is reportedly lower in Africa. The treatment of thyrotoxicosis depends on the cause. Therefore, it is of substantial importance to establish the etiology following the diagnosis of the clinical syndrome.

The effect of sodium restriction on iodine prophylaxis: a review

PURPOSE

Sodium is essential to life. However, its dietary excess is detrimental to the cardiovascular system, and sodium restriction is a crucial step in cardiovascular prevention. Iodine deficiency has been fought worldwide for decades, and substantial success has been achieved introducing the use of iodine-enriched salt. Nevertheless, areas of iodine deficiency persist around the world, both in developing and industrialized countries, and a major concern affecting dietary sodium reduction programs is represented by a possible iodine intake deficiency. There are substantial differences in the source of alimentary iodine among countries, such as iodized salt added, household tap water, seafood, or salt employed in packaged food. It is clear that a sodium-restricted diet can induce differences in terms of iodine intake, depending on the country considered. Moreover, iodine status has undergone relevant changes in many countries in the last years.

METHODS

Systematic review of literature evidence about the possible effects of sodium restriction on population iodine status.

RESULTS

To date, the available results are conflicting, depending on country, salt iodization policy, as well as time frame of data collection. However, to ensure an optimal iodine supply by salt fortification, without exceeding the current recommendation by World Health Organization for salt intake, seems to be an achievable goal.

CONCLUSION

A balanced approach may be obtained by an adequate iodine concentration in fortified salt and by promoting the availability of iodized salt for household consumption and food industry use. In this scenario, updated prospective studies are strongly needed.

Assessment of the Impact of Salt Iodisation Programmes on Urinary Iodine Concentrations and Goitre Rates: A Systematic Review

Introduction

Two main strategies are currently recommended for the prevention and control of iodine deficiency in the world: implementation of universal salt iodisation programmes and permanent monitoring of iodine consumption by the population. Although iodine intake and coverage iodised salt have increased in the world population, iodine deficiency disorders (IDDs) may still be a public health problem in a few countries or communities.

Objective

To assess the impact of salt iodisation programmes on urinary iodine concentrations and goitre rates in the world population. Methodology. A systematic review based on the PRISMA method. We obtained articles from Scopus, Science Direct, MEDLINE databases, and other sources between March and April 2020, without limitation of dates. "Iodisation" AND "urinary iodine concentrations" AND "goitre" in English, Portuguese, and Spanish without filters and clinical trial, case-control, and cross-sectional studies were included in this review.

Results

Of 479 abstracts, twenty-three were eligible. Coverage on iodised salt was in the range of 16 to 98%, and 11 studies had been sufficient, whilst eight studies had adequate iodine concentration in salt and three excess. 81.8% of studies that had an adequate median of UIC had a good impact in their respective salt iodisation programmes.

Conclusion

After 18 years of salt iodisation programme implementation in the 13 countries, the majority achieved sustaining elimination of IDD whilst all had adequate median UIC; however, more detailed studies are still needed to confirm that all communities are equally protected of IDD.