Neonatal screening for congenital hypothyroidism in West Black Sea area, Turkey

Abstract

The aim of this study was to investigate the incidence of congenital hypothyroidism (CH) in the West Black Sea Area, a mild-to-moderate iodine deficient area in Turkey. Neonatal screening for CH was performed using blood specimens collected onto filter paper. Thyrotropin [thyroid-stimulating hormone (TSH)] was measured by radioimmunoassay, and a value >20 microU/ml was considered as cut-off point for re-examining. Venous serum was obtained to measure TSH, thyroxin (T4), free T4 (FT4) and thyroglobulin (TG). To determine the iodine status of the study area, median urinary iodine was measured in 212 randomly selected neonates and their mothers. A total of 18606 neonates were screened from three cities (Bolu, Düzce, and Zonguldak) between 2000 and 2002. With a cut-off point of TSH value >20 microU/ml, the recall rate was found 1.6%. Eight cases of CH were diagnosed (incidence 1/2326). There were three cases of transient hypothyroidism, with an incidence of 1/6202. Twenty-six percent of the TSH values was greater than 5 microU/ml. Median urinary iodine concentrations in neonates and their mothers were 85 microg/l and 40 microg/l, respectively. The incidences of CH, transient hypothyroidism and the recall rate were higher in our study area than many countries in Europe. The study area has been affected by mild-to-moderate iodine deficiency. Neonatal screening for CH should be introduced in Turkey without delay. A national comprehensive infantile hypothyroidism and iodine prophylaxis policies should be developed.

Higher Incidence Rates of Hypothyroidism and Late TSH Rise in Preterm Very-Low-Birth-Weight Infants at a Tertiary Care Center

“…Published data suggest an overall CH incidence of 1: 1,823 in Lebanon among term and preterm infants combined [19], which is slightly higher than reported rates from the US [20, 21], Europe [21], and some countries in the region [22-25]. To our knowledge, there are no published data in Lebanon regarding screening protocols or rates of CH among VLBW infants.…”

Neonatal thyroid screening in a mild iodine deficiency endemic area in Iran

“…[15] The incidence of hypothyroidism was 2/1000, which is high as compared with that in other countries such as Finland, Hungary, and Turkey. [12,16] Our patients were under treatment, and we could not distinguish between the forms of hypothyroidism. Since salt iodization program has reduced goiter rate in Iran, [17] we thought the transient type is the main form of hypothyroidism in the area.…”

“…[10,11] Also, a recall rate of 1.6% with a cut off point of 20 µU/mL has been reported in Turkey. [12] Several studies have confi rmed the validity of this policy as an acceptable index for evaluating iodine intake in populations. [13,14] The frequency of neonatal blood TSH, spotted on fi lter paper, was above 3%, which indicated a mild iodine defi ciency (ID) in the area on the basis of the proposal made by WHO/UNICEF/ICCIDD.…”

Impact of Lower Screening TSH Cutoff Level on the Increasing Prevalence of Congenital Hypothyroidism

“…The increased prevalence of CH after reducing the cutoff point is not necessarily a single predictor of transient TSH elevation [3], but in our case the prevalence of transient CH increased more than 8-fold. Similarly, an approximate 5-fold increase in the prevalence of transient CH has been reported in Turkey after reducing the cutoff point (1/1154 vs. 1/6202) [10,20]. The percentage of transient CH within the entire CH group revealed in our study showed an increment from 5.5% of all CH to 29.2%, indicating the important contribution of the lower TSH cutoff level in detecting additional cases of transient CH.…”