Screening for congenital hypothyroidism was carried out by measuring thyroid stimulating hormone (TSH) on dried blood spots (mean + 2SD cut oV value 12 µU/ml) by fluoroimmunoassay using DELFIA kits. A total of 20 021 infants were screened, and seven cases with congenital hypothyroidism were detected, giving an incidence of congenital hypothyroidism of 1:2860 (female:male ratio 6:1). In four of seven infants with congenital hypothyroidism (57%) the mother also had thyroid disease, supporting the importance of genetic factors as a cause of congenital hypothyroidism. Transient hyperthyrotropinaemia occurred in 654 infants (recall rate 3.3%). There was a significant association of transient hyperthyrotropinaemia only with cardiac failure at birth or caesarean section (p<0.01). Family studies showed no predisposition to thyroid diseases associated with a transient increase of TSH. (J Med Screen 1998;5:20-21) Keywords: neonatal screening; congenital hypothyroidism; thyroid stimulating hormone; hyperthyrotropinaemia Neonatal screening for congenital hypothyroidism, started in 1989, was the first genetic screening programme in Estonia.1 Methods Blood samples were obtained from 99% of newborns aged 3 to 5 days at three maternity hospitals and transferred to filter paper cards (Schleicher and Schuell No 2992). These cards contained information about the sex, nationality, birth date, date on which the sample was taken, gestational age, birth weight, height, and abnormalities of the infants. The cards were stored in bags between 2°C and 8°C for one to 14 days.Screening for congenital hypothyroidism was carried out by measuring the concentration of thyroid stimulating hormone (TSH) on a single dried blood spot specimen (punch size 3 mm with equivalent blood volume 4.8 µl by packed cell volume 50%) using a solid phase fluoroimmunoassay with the DELFIA neonatal hTSH kits (Wallac Oy, Turku). The fluorescence was read by the Arcus fluorometer 1230 (LKB, Wallac). The intra-assay and interassay variations were 4.5-6.6% and 4.7-5.7% respectively. The results from 415 normal newborns gave a cut oV value for TSH of 12 µU/ml (mean + 2SD).The screening was carried out in three stages: (a) TSH concentration was measured on the first dried blood spots in the institute laboratory; (b) when the TSH concentration was above the cut oV value the infants were recalled and TSH measurement repeated on a second filter paper; (c) if the TSH concentration when retested was still over the cut oV value TSH, thyroxine (T4), and triiodothyronine (T3) concentrations were measured in the serum to confirm the diagnosis. The diagnostic criteria for congenital hypothyroidism were: (a) a TSH concentration above the cut oV value (12 µU/ml) on the first and second blood spot analysis; (b) a TSH concentration in serum above normal (more than 15 µU/ml) but T4 and T3 concentrations below the normal value in serum; (c) the existence of clinical features of congenital hypothyroidism and an abnormal thyroid scan.When screening was positive, additional dat...

According to neonatal thyroid screening the incidence of congenital hypothyroidism in Estonia is 1:2,860. Transient hyperthyrotropinemia with a raised thyroid-stimulating hormone level of 5 μU/ml occurred in 17.7% of infants and was not associated with low birth weight, small birth length, low gestational age or congenital anomalies. Based on WHO criteria (WHO/UNICEF, 1994) it corresponds to mild iodine deficiency in Estonia (3% or less is in iodine-sufficient areas). This is in agreement with the previously reported median urinary iodine content of 65 μg/l in children. The frequency of infants with TSH >5 μU/ml was 16.4, 21 and 17.2% in three regions (north, central and south) of Estonia, respectively, indicating mild to moderate iodine deficiency. These findings show the possibility of using the results of newborn screening for congenital hypothyroidism to assess the severity of iodine deficiency in Estonia. The introduction of universal iodine prophylaxis is recommended.

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The results of a routine and fluorescence microscopic investigation of chromosomes are presented in 208 normal adults and 141 mentally retarded children (80 with diagnosis of "mental retardation of unknown etiology" and 61 with Down's syndrome). The occurence of both real chromosome aberrations and chromosome variants are presented, with special attention being paid to the chromosome variants. The data obtained show that in all groups studied there is considerable polymorphism of heterochromatic regions that appears to be dependent on sex and connected with the origin of some pathologic conditions.