|The Prevention and Control of Iodine Deficiency Disorders - Nutrition policy discussion paper No. 3 (UNSSCN, 1988, 130 p.)|
Recent evidence indicates a vide spectrum of disorders resulting from severe iodine deficiency which puts at risk more than 400 million people in Asia as well as millions in Africa and South America. These iodine deficiency disorders (IDD) include goitre at all ages, with associated impairment of mental function; endemic cretinism characterized most commonly by mental deficiency, deaf-mutism and spastic diplegia and lesser degrees of neurological defect related to foetal iodine deficiency; increased stillbirths, perinatal and infant mortality.
Evidence is now available from both controlled trials and successful iodization programmes that these disorders can be successfully prevented by correction of iodine deficiency.
The social impact of IDD is great. Prevention will result in improved quality of life, productivity, and educability of children and adults. It is now clear that iodine deficiency is a major impediment to human development.
Iodized salt and iodized oil (by injection or by mouth) are suitable for correction of the condition on a mass scale. Alternative vehicles for iodine supplementation need to be sought.
A single injection of iodized oil can correct or prevent IDD for three to five years. Such injections offer a satisfactory immediate measure using primary health care services for the millions living in regions where iodized salt cannot be used, until a salt programme can be effectively implemented. Iodized oil could also be administered orally through the primary health care system.
In general, IDD can be categorized at three levels of severity:
(a) Mild IDD with goitre prevalence in the range 5-20% (school-children) and with median urinary iodine levels in excess of 50 mcg/g of creatinine. Mild IDD can be controlled with iodized salt at a concentration of 10-25 mg/kg (or ppm). It may disappear with economic development;
1See footnote in Section 4.8
(b) Moderate IDD with goitre prevalence up to 30%, some hypothyroidism with median urinary iodine levels in the range 25-50 mcg/g of creatinine. Moderate IDD can be controlled with iodized salt (25-40 mg/kg). Otherwise, iodized oil either orally or by injection should be used through the primary health care system;
(c) Severe IDD indicated by a high prevalence of goitre (30% or more), endemic cretinism (prevalence 1-10%), median urinary iodine below 25 mcg/g creatinine. Severe IDD requires iodine as iodized oil administered either orally or by injection - the fastest and most effective method-for complete prevention of central nervous system defects.
The main hazard of iodization is transient thyrotoxicosis seen mainly in adults over the age of 40. It is caused by autonomous thyroid function resulting from long-standing iodine deficiency. It can be minimized by lessening iodization for those over the age of 40.
The availability of suitable technology, while the basic requirement for a national iodization programme, is only one element of an IDD control programme. The reasons for success or non-success in various programmes have been investigated, and political, social and economic factors have all been found to be relevant. Experience indicates that there is a social process involving six elements or steps which comprise the programme.
They are as follows:
(a) Situation analysis: epidemiological data on IDD, including goitre surveys, with data on water iodine and urinary iodine levels and if possible thyroxine (T-4) levels.
(b) Communication of: operational data to health the findings professionals and the public with the assistance of the media using a social marketing approach.
(c) Plan of action: to be developed by the Ministry of Health with a national inter-sectoral IDD control commission, based on situation analysis with options dependent on cost considerations, including consultation and assistance from international agencies and bilateral support.
(d) Political support: to be developed following (a), (b) and (c). Concept of IDD expressed in social terms is essential. Authority to be given to the national IDD control commission with full political and legislative powers to carry out the programme.
(e) Implementation: organization of staff and resources, training, and establishment of cooperation with region.
(f) Monitoring and: measurement of effects on urinary evaluation iodine (salt iodine) and blood T-4. Evaluation by surveys of IDD incidence and prevalence.
There is a need for better coordination of research and iodization programmes focussed on the eradication of IDD. This has led to the establishment of an international consultative group similar to that already established for Vitamin A (IVACG) and nutritional anaemia (INACG). This is the International Council for Control of Iodine Deficiency Disorders (ICCIDD) which provides an expert resource for international agencies and national governments on all aspects of IDD and IDD control programmes.
Priority attention should be given to the prevention and control of severe IDD. This means that resources and technology can be focussed with particular reference to the use of iodized oil. A plan involving population targets and only can be drawn up with reference to previous experience with the EPI programme in many countries. With a moderate allocation of resources major progress could be achieved in a number of countries within the next five to ten years.
A resolution of the 39th World Health Assembly notes that prevention and control of IDD as a public health problem by reduction of goitre rates below 10 percent in schoolchildren is feasible within the next five to ten years. It also noted that such control will lead to improved quality of life and productivity and improved educabillty of children and adults and so make a significant contribution to health for all by the year 2000.