کرتینیسم

To assess the relationship between parental consanguinity and permanent congenital hypothyroidism (PCH). From February 1998 to August 2002, cord dried blood spot samples, viz. only live births, in eight hospitals and a rural birth center in Tehran and Damavand were collected on Whatman BFC 180 filter papers. Samples with cord TSH  20 mU/L (two-site IRMA) were recalled. Between 7-14 days of life or thereafter, congenital hypothyroidism (CH) was confirmed by serum TSH > 10 mU/L and T4 < 6.5 g/dL and L-T4 was immediately started. CH-affected newborns were followed-up until May 2003. Thyroid dysgenesis was determined using 99m technetium pertechnetate thyroid scanning and/or ultrasonography. In thyroid eutopic newborns, dyshormonogenesis was diagnosed by a 4-week discontinuation of L-T4 between 2-3 years of age followed by abnormal serum TSH and T4 values. Of 35067 specimens, 373 (1.06%) were recalled, 25 had PCH (1:1403 births), 18 had thyroid dysgenesis (1:1948 births), and 7 had thyroid dyshormonogenesis (1:5010 births). Twenty-one PCH cases were detected from July 2000 onwards and 6648 (28.6%) of 23227 neonates had parental consanguinity. The odds ratio of parental consanguinity in PCH was 2.75 (95%CI: 1.17-6.47 P=0.02) and in dysgenesis was 3.74 (95%CI: 1.33-10.52 P=0.01) and the odds ratio of first-cousin parental consanguinity in PCH was 2.96 (95%CI: 1.23-7.15 P=0.02) and in dysgenesis was 3.21 (95%CI: 1.14-9.02 P=0.03) compared to non-PCH and non-dysgenetic cases, respectively. Parental consanguinity can be considered as the possible causative factor for the high prevalence of PCH and dysgenesis in Tehran.

Following screening of newborns for congenital hypothyroidism (CH) in Tehran for 49 months and in Damavand for 21 months, a question was raised as to whether there are any differences between the recall rates and CH incidences in metropolitan and district populations. The present study was conducted to address the aforementioned issue. From February 1998 to March 2002, cord blood spot samples from 8 hospitals and a rural birth center in Tehran (the capital) and Damavand (district) were collected and tested for TSH measurement using a two site IRMA method. TSH values  20 mU/L were recalled. The diagnosis of CH was confirmed using age-adjusted reference values for serum TSH and T4 levels. The frequency distribution of recalls and CH cases in Tehran and Damavand were compared using 2 and Fisher’s exact tests, respectively. Of 30085 (Tehran: 28001 and Damavand: 2084) screened neonates, 319 (Tehran: 297 and Damavand: 22) had cord TSH values  20 mU/L. The recall rate was 1. 06% (Tehran: 1. 06% and Damavand: 1. 06%). Thirtyـtwo (Tehran: 30 and Damavand: 2) neonates had CH. The CH incidence was 1 in every 940, 933, and 1042 live births in total, Tehran, and Damavand populations, respectively. A total of 5119 out of 18260 (28%) neonates had parental consanguinity. This was 4582 out of 16178 (28. 3%) in Tehran and 537 out of 2082 (25. 8%) in Damavand. The recall rates and CH incidences were not significantly different in Tehran and Damavand. Preliminary findings of CH screening program showed that recall and CH occurrence do not have significantly different distributions in Tehran and Damavand and CH was prevalent in both regions. It could be concluded that CH might be prevalent in other parts of the country.

The recall of neonates with primary abnormal tests has almost always been considered the first step in the detection of congenital hypothyroidism (CH) in the CH screening programs. Considering recall rate as one of the indicators of cost-benefit and operational feasibility assessment of a program, forecasting of recall rate(s) could be beneficial to an optimized allocation of funds and resources. The trend of time-series of neonatal monthly recall rates was assessed in this report. From March 1998 to March 2002 (48 months), cord blood spot samples from 8 hospitals and a rural birth center in Tehran and Damavand District were collected on filter papers (Whatman BFC 180). TSH values were measured in the Endocrine Research Center laboratory using a two-site IRMA method. Primary TSH levels  20 mU/L were considered abnormal and recalled for serum confirmatory tests. Monthly recall rate (total number of primary TSH levels  20 mU/L to total live births per month  100) was recorded for 48 consecutive months. Monthly recall rates were analyzed using linear models of Box and Jenkins (ARIMA). The autoregressive model was fitted to forecast the next recall rates with a 95% confidence interval. Out of 29908 cord blood spot samples, 314 showed TSH levels  20 mU/L (total recall rate of 1.05%) of whom 32 had CH (1: 935 live births). Total data showed normal distribution and were stationary. Fitting of particular type of AR(3) model showed that monthly recall rate is predictable according to the recall rate obtained three months ago. Therefore, the autoregressive model of zt = 0.67 + 0.45 zt-3 + et, with significant parameters (p  0.003), was obtained to forecast the next recall rates, ultimately. Forecasting of monthly recall rates is possible using the autoregressive model.