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Objectives: Clinical laboratories store filter paper samples used in neonatal screening for various periods of time after performing hormonal measurements. However, due to lack of data concerning specimen stability, it is unclear for how long these samples should be stored. The objective of this study is to determine the stability and reproducibility of thyroid-stimulating hormone (TSH), thyroxine (T(4)) and 17-hydroxyprogesterone (17-OHP) measurements in filter paper blood samples stored for up to 60 months., Methods: Two hundred and twenty-eight blood samples, drawn between the second and the fourth day of life, were divided into seven distinct groups and kept at 4-8 degrees C for one day or 2, 12, 24, 36, 48 or 60 months after basal hormonal measurements. In each group, TSH, T(4) and 17-OHP levels were initially assayed 24-48 hours after collection (basal) and repeated once at the end of storage timing. All the measurements were performed by time-resolved fluorometry (1235 AutoDELFIA, Wallac Oy, Turku, Finland). Repeated and basal levels of each hormone were compared within the same group by Student's paired t-test. Differences were considered significant at P < 0.05., Results: Compared with basal measurements, TSH and T(4) levels declined significantly only when these hormones were re-assayed at 48 or 60 months of sample storage. In contrast, 17-OHP concentrations decreased earlier, starting at 24 months and continuing throughout the remaining period., Conclusion: Our data suggest that neonatal screening of filter paper samples kept at 4-8 degrees C are reliable for repeating the hormonal measurements when specimens are stored for up to one year, in the case of 17-OHP, or three years, in the case of T(4) and TSH.

Objective: Symptoms of hypothyroidism in adults can be mistaken for medical and psychiatric diseases, as well as for general signs of ageing such as weakness, lethargy and fatigue. The incidence of hypothyroidism is many-fold higher in adults than in newborn children. The latter have been routinely screened for the condition using filter paper dried blood spots (DBS) for nearly three decades but this cost-effective screening technique has only recently been applied to adults. This study was undertaken to show that DBS testing in adults and older children is an accurate way to screen for hypothyroidism., Methods: Serum and DBS specimens were collected from adults and children. Assays were run on both specimens and the results correlated. In addition 972 specimens were collected from adults at community centres and nursing homes. Follow-up studies were performed on patients with positive results., Results: The correlation coefficient for 118 matched serum and DBS specimens was 0.99. Thyroid-stimulating hormone (TSH) values were elevated in 50 of the 972 adults from nursing homes and community centres. Thirteen of these individuals were on thyroid medication and 28 had either high serum TSH or high thyroglobulin (TgAb) or thyroid peroxidase (TPOAb) antibody levels., Conclusions: Individuals can be screened for hypothyroidism by collecting finger stick DBS specimens at community centres, nursing homes and other locations which can be mailed by regular postal service to a central laboratory for accurate and inexpensive testing.

Screening for hypothyroidism has been achieved by seeking raised concentrations of thyroid stimulating hormone (h-TSH) in dried blood samples collected on absorbent paper from some 1700 newborn babies each week using double antibody radioimmunoassay and 125I-label counting on a NE1600 gamma counter linked to a HP9815S desk top calculator. Specificity, accuracy, and quality control of the assay have been investigated. The calculator programme stores all count, time, and calculated data and uses log-log function formation and third-power homoscedastic polynomial fit to the calibration data followed, if necessary, by elimination of outliers set at P = 0.5%. Branching in the calculation procedure provides the ability to process sample data in subgroups, completely to reprocess data (including presentation in a form suitable for making a histogram plot), and to reset without loss of data in case of instrument or main power failure. Variance analysis was used to select the minimum duration of count (50 s), and it was demonstrated that homoscedasticity pertains in the regression calculation.

A multicentre study for the detection of congenital hypothyroidism by enzyme-immunoassay of thyrotropin in filter paper blood spots is described. The method is accurate, with good precision and adequate sensitivity. No interference due to common blood constituents has been observed. Moreover, the TSH determination can easily be performed by photometric measurement of enzyme activity. Large series of samples can be processed by automation using common laboratory analysers. Values show good agreement with those obtained by RIA methods. We present a method for screening for congenital hypothyroidism which can be performed in all clinical laboratories.

The radioimmunoassay described measures TSH in dried whole blood spots collected from neonates onto filter paper Guthrie cards. Microgranular cellulose is added to the precipitating reagent at the critical separation stage of the assay to overcome imprecision caused by the presence of the filter paper sample disc in the tube. The method was developed for a regional neonatal screening unit and has been found to be very reliable during ten months' routine use. It was required to be as precise, sensitive, accurate, rapid, simple, and inexpensive as possible and suitable for use with automatic diluting equipment in order to process large numbers of samples. Other methods were examined for their suitability and found not to fulfil one or more of the above criteria.