Iodine deficiency not only causes endemic goiter and cretinism but also a wide spectrum of disabilities which includes deaf mutism, mental and physical retardation and various degrees of neuromotor dysfunction(1).

Surveys conducted in 239 districts of 25 states and 4 union territories have identified 197 districts as endemic for IDD. The states having a high prevalence of goitre include Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana, Bihar, Uttar Pradesh, West Bengal, Sikkim, Assam, Mizoram, Meghalaya, Tripura, Manipur, Nagala.n9 and Arunachal Pradesh. Others include the National Capital Territory of Delhi, Maharashtra, Madhya Pradesh and Gujarat(2,3).

The district Hamirpur, Himachal Pradesh is a known iodine deficiency endemic area. A survey conducted in 1956 reported a goiter prevalence of 41.2% in the district(4). To ensure adequate availability and use of iodised salt, the government of HP issued a ban on the sale of non-iodised salt for human consumption in 1976(5). Under this ban notification iodised salt with a mmimum of 30 ppm iodine at the manufacturer's level and 15 ppm iodine at the consumer level should be available in the state.

The present study was conducted with the objective to assess the current prevalence of 100 in district Hamirpur and to estimate the iodine content of salt consumed by population in the district.

Subjects and Methods

The study was conducted in the district Hamirpur of Himachal Pradesh. The multi- stage cluster sampling methodology was followed for selecting the survey sites. The district Hamirpur has a total population of 3,86,295. All the rural and urban units in the district with their respective populations were enlisted. The 30 clusters to be surveyed were selected by using population proportionate to size sampling methodology. In each population unit one or more schools were covered till the sample size of 220 children in the population unit was not covered.

Children in the age group of 8-10 years were considered for the present study. School children in this age group are recommended for the assessment of IDD because of their combined high vulnerability to disease, representativeness of their age group in community and easy accessibility(6). In Himachal Pradesh, the school enrollment of primary classes was more than 90% and hence the school approach was adopted.

Calculation of Sample Size

The sample size of children to be surveyed was calculated with a presumption that the prevalence of goitre at the time of the survey was 15%. The Confidence level of 95%, relative precision of 10% and de- sign effect of three was considered for calculation of sample size. Utilizing these parameters a sample size of 6570 was obtained (i.e., 219 children per cluster).

Selection of Subjects

In each identified population unit (cluster), all the primary schools were enlisted and one school was selected for the de- tailed survey. In each school, about 220 children were surveyed. If the sample could not be covered in the school, an ad- joining school was included to complete the sample of a cluster. The school teachers and children were briefed about the activities to be undertaken during the survey. Subsequently, the children between 8-10 yrs of age were identified with the help of school records for inclusion in the study. An attempt was made to study an equal number of children (70-80) in the ages of 8, 9,10 years.

Assessment of Goiter

The clinical examination for goiter was done by the first. three authors who are public health specialist with 20 years of experience. Grading of goiter was done according to the criteria recommended by the joint WHO/UNICEF/ICCIDD. The goiter was classified into three categories: (i) Normal: 'When neck is in normal position, goitre neither palpabe nor visible; (ii) Grade I: When neck is in normal position, goiter not visible but palpable; and (iii) Grade II: When neck is in normal position, and goitre visible. In doubt, investigators were asked to record the immediate lower grade. Inter- observer variation was controlled by initial training in goiter grades by the experts. The sum of grades 1 and 2 provided the total goiter rate (TGR) in the study population.

Urinary Iodine Excretion

On the spot urine samples were collected from 20% of the subjects (every fifth child included in the study). The casual urine samples were collected in wide mouthed screw capped plastic bottles (one drop of toluene was added to each sample to inhibit bacterial growth and to minimize bad odour). Iodine was determined by the wet digestion method(7). The results were expressed as mcg iodine/ dl urine.

Iodine Content of Salt Consumed

In each cluster, about 100 salt samples were randomly collected from the school children who were included (every second child) in the study. The subjects were asked to bring about 20g of salt which was routinely being consumed in their respective homes in autoseal polythene pouches. The iodine content of the salt was estimated by the spot testing kit (STK). The STK has a sensitivity of 85% and specificity of 71 % (developed by MBI Chemicals, Madras)(8).

Results

A total of 6897 school children in the age group of 8-10 years were included for the study. Three thousand four hundred and eleven males and 3486 females were studied. The total goitre prevalence rate was found to be 8.8%. The prevalence of goiter in male and female children is shown in Table I. No significant difference was found in goiter prevalence amongst the male and female children.

It was found that 7.0 (n = 99), 8.8% (n = 125) and 17.0% (n = 240) of the children had urinary iodine excretion (DIE) levels of < 2, 2-4.9, and 5-9.9 mcg/ dl, respectively. Nine hundred and forty nine children had UIE of 10 mcg/ dl and above. The median urinary iodine excretion of the children studied was found to be 14.0 mcg/ dl.

It was observed that salt with a nil iodine content was consumed only by 2.5% of the beneficiaries. About 10.8% of families consumed salt with an iodine content of less than 15 ppm.

Discussion

It has been recommended that if more than 5% school age children (8-12 yrs) are suffering from goitre, the area should be classified as endemic to iodine deficiency(7). In the present study, a total goitre prevalence rate of 8.8% was found, signifying that in district Hamirpur, HP mild iodine deficiency existed. An earlier study in 1956, a goitre prevalence of 41.2% was reported in the district. The decrease in the prevalence of TGR could be possibly attributed to the availability of iodised salt to the beneficiaries.