Validation of a simple, manual urinary iodine method for estimating the prevalence of iodine-deficiency disorders, and interlaboratory comparison with other methods.

The measurement of urinary iodine in population-based surveys provides a biological indicator of the severity of iodine-deficiency disorders. We describe the steps performed to validate a simple, inexpensive, manual urinary iodine acid digestion method, and compare the results using this method with those of other urinary iodine methods. Initially, basic performance characteristics were evaluated: the average recovery of added iodine was 100.4 +/- 8.7% (mean +/- SD), within-assay precision (CV) over the assay range 0-0.95 mumol/L (0-12 micrograms/dL) was < 6%, between-assay precision over the same range was < 12%, and assay sensitivity was 0.05 mumol/L (0.6 microgram/dL). There were no apparent effects on the method by thiocyanate, a known interfering substance. In a comparison with five other methods performed in four different laboratories, samples were collected to test the method performance over a wide range of urinary iodine values (0.04-3.7 mumol/L, or 0.5-47 micrograms/dL). There was a high correlation between all methods and the interpretation of the results was consistent. We conclude that the simple, manual acid digestion method is suitable for urinary iodine analysis.

Control of iodine deficiency using iodination of water in a goitre endemic area.

Salt iodination is the method of choice for prevention of iodine deficiency in most parts of the world. However, establishment of such a program frequently involves considerable changes in the marketing and distribution patterns and requires years to achieve. This study was conducted to evaluate the efficiency of using well-defined water sources containing iodine-saturated silicon matrices for providing adequate iodine supply to an iodine deficient population in Kordofan State, Western Sudan. A system of water iodination using silicon matrices containing 30% sodium iodide placed in polyethylene baskets was used in four villages using either traditional wells or hand pumps. Before and every 6 months after iodination of water, urine and blood samples were obtained for determination of iodine and thyroid-related hormones, respectively. Goitre assessment on the village populations were performed at the start and 2 years later. Improvements in iodine status were recorded in all the study villages. The water iodine concentrations increased and a higher iodine content was observed in the hand pumps compared to the traditional wells. The median urinary iodine concentrations increased significantly, from 0.19, 0.20, 0.19, 0.11 to 1.20, 1.10, 0.37, 0.30 mumol/l in the four villages, respectively. The percentages of subjects with serum TSH above 4 mU/l were decreased from more than 30% before iodination to less than 15% at 2 years after iodine supply and the mean serum thyroxine hormone values rose. The rates of goitre decreased from 69% to less than 25%. The study shows that this system is effective, cheap, safe and practically applicable under conditions prevailing in rural areas in developing countries with iodine deficiency.

Breastfeeding in Belgium: tentative evaluation based on neonatal screening cards.

In Belgium as in most developed countries, the proportions of breastfed to bottle-fed newborns is poorly known. A compilation of infant feeding information, available on cards which were completed at the time newborns were screened for inborn metabolic errors, indicates that in the years 1992 and 1993, 62.5 percent of infants were breastfed on day five of life. The data collected in this way were consistent for the years studied. Other countries may also be able to use screening cards to estimate breastfeeding initiation rates.

The effects of different doses of oral iodized oil on goiter size, urinary iodine, and thyroid-related hormones.

The prevention of iodine deficiency is still a worldwide concern. This study, conducted in Soja in western Sudan, was carried out to evaluate the effects of a dose of iodized oil sufficient enough to give maximum protection against goiter and provide an acceptable iodine supply without side-effects over a sufficiently long period of time. Adult goitrous subjects (n = 117) were randomly assigned to three groups, A, B, and C, and received a single oral dose of 200, 400, or 800 mg iodine, respectively. Urine and blood samples were collected at the start of the study and monitored for 1 yr. In the 3 groups, mean serum T4 and median urinary iodine and serum TSH values were restored to reference limits, and these were maintained for about 1 yr. In each treatment group, about two thirds of the subjects displayed a reduction in goiter size, and the 400- and 800-mg doses were not more efficient than the 200-mg dose to accomplish normalization of thyroid hormone values. A temporary rise in TSH was noted 1 week after iodine administration in 1, 3, and 10 subjects, respectively, and 1, 0, and 3 subjects showed biochemical signs of thyrotoxicosis during the year after treatment with the 3 different doses. The data indicate that oral administration of 200 mg iodine is effective and acceptable for treating iodine deficiency in adults for 1 yr. Because of the risks of side-effects and the shortage of medical resources, higher doses are not recommended.

Age influence on clinical features in hospitalized thyroid patients: dissimilarity between clinical and laboratory findings in adulthood. A retrospective study.

To evaluate the influence of age on clinical findings of thyroid disease, the records of 209 consecutive hospitalized patients with hyperthyroidism (n = 109) or hypothyroidism (n = 100) over a ten year period (1979 to 1988) were retrospectively reviewed. Patients included 51 males and 158 females, aged 21-99 years. Control euthyroid subjects (n = 70) were selected in the same age range and for similar non-thyroid illness as patients. Patients and controls were sorted by age decade of life. For each group a clinical index was calculated on the basis of 10 symptoms and 10 signs most frequently observed in thyroid disease. With increasing age, the occurrence rate of the clinical manifestations of thyroid disease decreased in patients while it increased in controls. This opposite evolution was less marked in hypothyroidism than in hyperthyroidism and was independent of biological parameters which remained stable whatever the age of patients and controls. Specific clinical features were identified for hyper- and hypothyroidism but none of them had sensitivity higher than 60% except goiter in hyperthyroid patients aged 61-80. In conclusion, a clinical diagnosis of thyroid disease is difficult in aged subjects because there are only a few specific features and their frequency is low. Therefore, in subjects over 60 years, we advocate performance of thyroid biochemical screening.

Evolution of osteocalcin, alkaline phosphatase and parathyroid hormone after parathyroidectomy in patients receiving chronic maintenance hemodialysis.

Parathyroid hormone (PTH), osteocalcin and alkaline phosphatase (AP) were investigated before and after parathyroidectomy in 12 patients receiving hemodialysis. Early post-parathyroidectomy, PTH decreased (p less than 0.001), AP increased (p less than 0.05), but osteocalcin remained unchanged. At 3 months, osteocalcin and AP declined. A negative correlation was observed between aluminum staining and post-parathyroidectomy osteocalcin. In conclusion, early post-parathyroidectomy, osteocalcin and AP reflect persistent osteoblastic activity, which declined after 3 months. In patients receiving hemodialysis both variables may represent different aspects of osteoblastic activity and osteocalcin allows mixed uremic osteodystrophy after parathyroidectomy.

Biochemical thyroid profile in patients infected with the human immunodeficiency virus.

Over a 2-year period, thyroid function was studied in 102 patients infected with the human immunodeficiency virus (HIV) and in 102 age- and sex-matched controls with various infectious diseases. Biochemical abnormalities were observed in 1-20% of the patients, depending on thyroid indices, but thyroid disease (hypothyroidism) was diagnosed in only 1. Compared to controls, patients, especially those with the acquired immunodeficiency syndrome (AIDS), had a significant increase in serum thyroxine-binding globulin, a lower T3 and free thyroxine index, and a higher frequency of thyroglobulin antibodies.

Superiority of thyrotropin to thyroxine as a tool in the screening for congenital hypothyroidism by the filter paper spot technique.

The effects of storage on the assessment of thyroxine (T4) and thyrotropin (TSH) were evaluated in blood spots collected on filter paper according to the methods commonly used in screening for congenital hypothyroidism. Comparisons were made with serum values obtained simultaneously in the same subjects. In samples stored at room temperature a clear-cut decrease in T4 was observed after 24 hours while TSH was stable for at least 15 days. Spot samples collected in an area of severe endemic goiter in Africa and analyzed in Brussels displayed a systematic decrease in T4 (up to 133 nmol/l) while TSH was fairly stable. Spot samples collected in Belgium were stored at -18 degrees C and were reassayed after 1 year; they did not show any significant change in TSH but a systematic decrease in T4. We conclude that spot TSH is the tool of choice in screening for congenital hypothyroidism particularly in developing countries and that spot T4 should not be used for field studies or under any circumstances in which assays cannot be performed very soon after blood collection.