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PubMed1990

Neonatal apo A-I, apo B, and apo(a) levels in dried blood spots in an Australian population.

We measured neonatal apo A-I and apo B by ELISA, and apo(a) by RIA, in capillary blood spotted onto filter paper in samples also used for routine neonatal screening in 1032 consecutively born babies. In the 2- to 5-d-old babies with birth weights greater than or equal to 2.0 kg (n = 919), mean +/- SD levels of apo A-I and B were 0.48 +/- 0.19 g/L and 0.24 +/- 0.14 g/L of whole blood, respectively. The apo A-I levels were affected by birth weight (negatively) and by age at sampling (positively). The apo B levels were affected positively by both variables, and girls had higher levels than boys (p less than 0.01). These variables accounted for 3.5 and 6.2% of apo A-I and apo B variability, respectively (p less than 0.001). The apo(a) levels (mean +/- SD, 20 +/- 23 U/L; median, 14 U/L, n = 1032) were unaffected by these factors. After adjustment for these variables, apo A-I levels were nearly normally distributed, whereas those of apo B were still positively skewed. The apo(a) distribution was strongly positively skewed and 1.2% of babies had levels above the equivalent of 25 mg/dL of lipoprotein(a) in serum. Our study shows that blood spots can be used to estimate apo A-I, apo B, and apo(a) levels in neonates, and establishes normal ranges. The results suggest that the apo(a) gene is expressed during the 1st postnatal week and that levels are independent of birth weight and apo A-I and B concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

Transient congenital hypothyroidism due to maternal thyrotrophin binding inhibiting immunoglobulin.

Transient congenital hypothyroidism due to maternal thyrotrophin binding inhibitor immunoglobulin (TBII), a thyroid-stimulating hormone (TSH)-receptor blocking antibody, is described in three male siblings born to a mother with autoimmune thyroiditis. These cases are believed to be the first described in Australia. The first child was found to have a serum TSH of 565 mU/L and had a negative thyroid scan when presented for neonatal screening. He was treated with thyroxine but became thyrotoxic at 3 months of age when he was on a dosage of 85 micrograms/m2 of body surface area. He was euthyroid 6 months after discontinuation of therapy. Nine years later a second hypothyroid sibling was born, with a serum TSH of 709 mU/L on day 4. Both mother and child were demonstrated to be strongly positive for TBII. Again this child was able to cease therapy by the age of 9 months. A third sibling, also TBII positive, was born 12 months after the second. His TSH was 90 mU/L and his serum thyroxine (T4) was 169 nmol/L. On this occasion, thyroid stimulation-blocking antibody was found to be present in the serum of both mother and child. Thyroxine therapy was ceased at 1 month. The family present a picture of varying degrees of transient neonatal hypothyroidism due to the transplacental passage of a maternal receptor blocking antibody. The condition is self-limiting, resolving when the immunoglobulin is cleared from the infant's circulation.

Adult↗
PubMed1983

A case of transient neonatal citrullinemia.

A male infant with transient citrullinemia is described. Initially, he was found to have hypertyrosinemia and hypermethioninemia upon routine neonatal screening for inborn errors of metabolism performed at 4 days of age and was revealed to have citrullinemia upon detailed examination of plasma amino acids. At 30 days of age, the plasma citrulline concentration was 13 mg/dl (normal, less than 0.8). In addition, the citrulline concentrations in the urine and cerebrospinal fluid (CSF) were markedly elevated. The blood ammonia and the CSF ammonia concentrations (300 micrograms/dl and 59 micrograms/dl, respectively) were also increased, but the infant showed no symptoms. Dietary protein intake was restricted to 2 g/kg/day, resulting in normalization of plasma citrulline and blood ammonia concentrations by 2 months of age. At 12 months of age, the infant was given a regular diet, and his physical and mental development was normal. 14C-citrulline incorporation into trichloroacetic acid (TCA)-precipitable material was normal in the fibroblasts. This report describes the first case in the literature of transient neonatal citrullinemia.

Amino Acid Metabolism, Inborn Errors↗
PubMed2006

Needs assessment and review of services for people with inherited metabolic disease in the United Kingdom.

Patients with inherited metabolic diseases need to be viewed as a specialist care group because of the range of expertise required for their diagnosis and management. In the UK, professional concerns have been expressed that existing services would struggle to meet needs resulting from new diagnostic and screening techniques, new treatments and increased survival. This needs assessment and service review was therefore undertaken at the request of the Joint Committee on Medical Genetics, guided by a national multidisciplinary stakeholder group. All 24 specialist centres identified in the UK provided evidence for the review. Approximately 10 000 patients are known to services and their annual number of referrals is increasing. Possible shortfalls in the number of patients attending specialist services were estimated for the UK as a whole by extrapolating the results from the region with the most comprehensive service and comparing this with known patient numbers. This analysis suggests that a further 5600 children and 3300 adults are not looked after by specialist services or have been lost to follow-up. The comprehensiveness of services was assessed using a new scoring system for clinical and organizational criteria. There are major regional disparities in the comprehensiveness of service provision across the country, with some regions having little or no specialist service. Unmet need will increase as a result of new diagnostic technologies, more effective treatments and new neonatal screening programmes; specialist services need to be developed and expanded to provide a comprehensive and more equitable service to the UK population.

Adult↗
PubMedDate not supplied

Regional experience with newborn screening for sickle cell disease, other hemoglobinopathies and G6PD deficiency.

BACKGROUND: Newborn screening for sickle cell disease, other hemoglobinopathies and G6PD deficiency is one of the most important means of decreasing mortality and morbidity in high prevalence areas. Nine years experience in newborn screening in Qatif Central Hospital are summarized. PATIENTS AND METHODS: All newborns in Qatif Central Hospital had cord blood screening for sickle cell disease, other hemoglobinopathies and G6PD deficiency using alkaline and electrophoresis, agar gel electrophoresis for sickle cell disease and fluorescent screening technique for G6PD deficiency. Families of infants with minor hemoglobinopathies and G6PD deficiency were informed about the results in the well baby clinic. RESULTS: From December 1992 to December 2001, 24 012 newborn were screened. 21 858 (91.03%) were Saudi and 2154 (8.97%) were non-Saudi. In the Saudi hemoglobin electrophoresis patterns, AF (normal) was found in 49.52%, hemoglobin FS (sickle cell disease) + FS Bart s (sickle cell disease with alpha thalassemia) in 2.57%, hemoglobin AFS (sickle cell trait) + AFS Bart s (sickle cell trait with alpha thalassemia) in 21.14%, and alpha thalassemia (based on elevated Bart s hemoglobin > or = 2%) in 35.68%. G6PD deficiency was found in 37.02% and 21.27% in males and females, respectively. Of 563 Saudi newborn with a presumptive diagnosis of sickle cell disease, 48 (8.5%) did not come to the hematology clinic or were not contactable. The diagnosis of sickle cell anemia or sickle thalassemia was confirmed in 513 patients, and 2 cases were found to have sickle cell trait on repeat testing. Many parents found it hard to accept the initial diagnosis and the resulting impact on their relationship with one another. CONCLUSION: Prevention and early identification of sickle cell disease, other major hemoglobinopathies and G6PD deficiency remains the cornerstone of management of these diseases. The main barriers to successful neonatal screening for hemoglobinopathies are the level of the education and deficiency in manpower. We recommend including newborn screening for hemoglobinopathies and G6PD deficiency in the national hypothyroidism screening program in the eastern province and the establishment of a special center for hemoglobinopathies with a high standard of medical care in Qatif.

Journal Article↗
PubMed2003

Cascade carrier-testing in cystic fibrosis.

It is good medical practice to offer carrier tests and counselling to the relatives of those affected by recessive disorders. Many are concerned about their own chances of having affected offspring. Cystic fibrosis carrier tests have been feasible since the discovery of the gene in 1989. It was generally agreed that although population screening was not practical, testing should be offered to relatives and their partners. There is evidence that such offers have not always been made and relatives have sometimes found it difficult to be tested. An active cascade programme of the counselling and testing of cystic fibrosis patients' relatives and their partners has operated from Royal Manchester Children's Hospital since 1993. The service operates with dedicated staff, backed up by a specialist cystic fibrosis molecular genetics laboratory and a specialist genetic counselling service. The main target groups are couples or individuals of child-bearing age. There is discouragement of the testing of young children and of grandparents beyond reproductive age, although, if parents or individuals are insistent, testing is often performed, after counselling. An audit of users has shown satisfaction, very few feeling that they were pressured into having the tests. The experience of other centres with cascade-testing in cystic fibrosis is summarised. Cascades can start whenever a sufferer or carrier is identified, although care should be exercised in instituting active cascades in the extended families of newborns identified as carriers in neonatal screening programmes.

Adult↗
PubMed2002

Foetal and neonatal thyroid disorders.

Thyroid hormones have been shown to be absolutely necessary for early brain development. During pregnancy, both maternal and foetal thyroid hormones contribute to foetal brain development and maternal supply explains why most of the athyreotic newborns usually do not show any signs of hypothyroidism at birth. Foetal and/or neonatal hypothyroidism is a rare disorder. Its incidence, as indicated by neonatal screening, is about 1:4000. Abnormal thyroid development (i.e. agenesia, ectopic gland, hypoplasia) or inborn errors in thyroid hormone biosynthesis are the most common causes of permanent congenital hypothyroidism. Recent studies reported that mutations involving Thyroid Transcriptor Factors (TTF) such as TTF-1, TTF-2, PAX-8 play an important role in altered foetal thyroid development. Deficiency of transcriptor factor (Pit-1, Prop-1, LHX-3) both in mother and in the foetus represents another rare cause of foetal hypothyroidism. At birth clinical picture may be not always so obvious and typical signs appear only after several weeks but a delayed diagnosis could have severe consequences consisting of delayed physical and mental development. Even if substitutive therapy is promptly started some learning difficulties might still arise suggesting that intrauterine adequate levels of thyroid hormones are absolutely necessary for a normal neurological development. Placental transfer of maternal antithyroid antibodies inhibiting fetal thyroid function can cause transient hypothyroidism at birth. If the mother with thyroid autoimmune disease is also hypothyroid during pregnancy and she doesn't receive substitutive therapy, a worse neurological outcome may be expected for her foetus. Foetal and/or neonatal hyperthyroidism is a rare condition and its incidence has been estimated around 1:4000-40000, according to various authors. The most common causes are maternal thyroid autoimmune disorders, such as Graves' disease and Hashimoto's thyroiditis. Rarer non autoimmune causes recently identified are represented by TSH receptor mutations leading to constitutively activated TSH receptor. Infants born to mothers with Graves' history may develop neonatal thyrotoxicosis. Foetal/neonatal disease is due to transplacental thyrotrophin receptor stimulating antibodies (TRAb) passage. It's extremely important recognizing and treating Graves' disease in mothers as soon as possible, because a thyrotoxic state may have adverse effects on the outcome of pregnancy and both on the foetus and newborn. Thyrotoxic foetuses may develop goitre, tachycardia, hydrops associated with heart failure, growth retardation, craniosynostosis, increased foetal motility and accelerated bone maturation. Neonatal Graves' disease tends to resolve spontaneously within 3-12 weeks as maternal thyroid stimulating immunoglobulins are cleared from the circulation but subsequent development may be impaired by perceptual motor difficulties. Hashimoto's thyroiditis is a very common autoimmune thyroid disease. In presence of maternal Hashimoto's thyroiditis, there are usually no consequences on foetal thyroid, even if antiTPO and antiTg antibodies can be found in the newborn due to transplacental passage. However there are some literature reports describing foetal and neonatal hyperthyroidism in the affected mothers' offspring.

Autoimmune Diseases↗
PubMed2005

A Scottish study of heel-prick blood sampling in newborn babies.

OBJECTIVE: to conduct a randomised-controlled trial to investigate the effectiveness of two heel-prick devices (Tenderfoot and Genie Lancet) used in the newborn-baby screening test. DESIGN: a randomised-controlled trial. PARTICIPANTS AND SETTING: the homes of 340 healthy term newborn babies discharged from the maternity unit of Stirling Royal Infirmary, Scotland. Data were collected between April and November 2003. INTERVENTIONS: babies were randomly allocated to be tested with either the Tenderfoot or Genie Lancet heel-prick device. MEASUREMENTS: primary study outcomes include (1) quality of the blood sample; (2) time taken to collect the sample; (3) number of heel pricks required to take the sample; (4) whether squeezing of heel was required; (5) pain expressed by the baby; and (6) presence of bruising. A potential intervening variable was the experience of the midwife. FINDINGS: on all outcomes, the Tenderfoot device was more effective than the Genie Lancet. Experienced midwives were more efficient in sample collection. KEY CONCLUSIONS: this study shows that the Tenderfoot device saves significant time for midwifery staff, improves baby care and reduces the need for more than one heel prick at each test, making it superior to the Genie Lancet device. IMPLICATIONS FOR PRACTICE: there is a case to be made for midwives to be issued with the Tenderfoot device for neonatal screening.

Analysis of Variance↗
PubMed2005

[Screening for congenital hypothyroidism in neonates of Zhejiang Province during 1999-2004].

OBJECTIVE: To analyze the data of screening for congenital hypothyroidism (CH) newborns in Zhejiang Province during 1999-2004. METHODS: The dried blood samples were collected on filter paper. The levels of thyroid-stimulating hormone (TSH) were measured by time-resolved fluoroimmunoassay, and the serum levels of TSH, triiodothyronine (T(3)) and thyroxine (T(4)) were detected by chemiluminescence. Infants with CH confirmed by neonatal screening were treated with levothyroxine (L-T(4)) initiated with 4-6 g/kg x d(-1 )for 2-3 years. Growth, development and intelligence status, scintigraphy or ultrasonography of thyroid, and bone age were investigated to evaluate the efficacy of therapy during follow-ups. RESULT: A total of 1112784 neonates were screened for CH during 1999-2004 with a coverage rate of 63.5%. Of the 6750 suspected CH cases, 6335 (93.8%) were recalled. 764 cases of CH were confirmed with an average incidence rate of 1 case CH per 1457 newborns (1/1457). 244 of 764 patients were followed-up for more than 1.5-2 years. All of them received thyroid by scintigraphy or ultrasonography. Among them 189 cases were found with normal gland, 35 with hypogenetic gland, 11 with ectopic gland, and the remaining 9 didn't show any image of thyroid. The average score of development quotient (DQ) was 106. 9. Among them, the DQ score was less than 85 in 2 cases, less than 90 in 9 cases, less than 100 in 28 cases, and in 68 cases the DQ was greater than 100. The bone age of 122 CH infants was evaluated with the X-ray radiography. In 90 cases of them,the bone age was normal, and 32 cases had progressed from development delay to normal. The height and weigh measured in all 106 cases had reached the related age criteria. The evaluation indicated that 55 cases were found with primary CH, 169 with temporary CH and 20 with subclinical CH. CONCLUSION: Neonatal screening for CH and regular treatment for CH patients are important for attaining normal body development and intelligence development of patients.

China↗
PubMed2005

Adrenal insufficiency in asymptomatic adrenoleukodystrophy patients identified by very long-chain fatty acid screening.

OBJECTIVE: Plasma assay for very long-chain fatty acids has made it possible to perform large-scale screening of at-risk individuals to identify asymptomatic patients with X-linked adrenoleukodystrophy (X-ALD). We evaluated the burden of undiagnosed adrenal insufficiency in 49 such patients (age, 4.5 +/- 3.5 years). STUDY DESIGN: Serum adrenocorticotropic hormone (ACTH) and standard-dose ACTH stimulation test were performed at the baseline and followed prospectively until initiation of adrenal replacement therapy (follow-up, 2 +/- 1.7 years). RESULTS: At baseline, 39 (80%) patients had impaired adrenal function, serum ACTH levels were elevated in 34 (69%) patients, and ACTH stimulation test was abnormal in 21(43%) patients. There was a moderate association between Serum ACTH and age at baseline, ( r = 0.32, P = .05). By the end of follow-up, 86% of patients had borderline or overt adrenal insufficiency (age of onset, 4.8 +/- 3.7 years). CONCLUSIONS: We detected a high prevalence of unrecognized adrenocortical insufficiency in asymptomatic boys with X-ALD. It is known to be a frequent cause of morbidity and can be prevented by careful monitoring, early identification of impaired adrenal reserve, and timely initiation of therapy. It manifests early and before onset of neurologic symptoms, suggesting X-ALD as a candidate disorder for neonatal screening.

Adrenal Insufficiency↗
PubMed1999

Automated, simplified GC/MS data processing system for organic acidemia screening and its application.

Gas chromatography mass spectrometry (GC/MS) is widely used in diagnosis of organic acidemias. However, GC/MS has not yet become a routine laboratory test, because of the complexity in interpretation of GC/MS data. We developed a personal computer-based system of automated metabolic profiling and disease detection for the screening of organic acidemias by GC/MS. The data were processed after the GC/MS analysis of urinary organic acids. In this system, 130 kinds of metabolites and 25 disorders of organic acids were enrolled for the search and detection, respectively. Metabolites were identified with methylene unit values (MU). target ions (Q- and C-ions) and their intensity ratios, and semiquantified by peak relative area (%) of the Q-ions to that of an internal standard. Metabolites whose values exceeded the cutoff of the control table were flagged as abnormal. The diseases or pathological condition were automatically evaluated by combination of the abnormal compounds. In this system, index metabolites were categorized into three groups. "AND, "OR" and "NO". The groups, "AND" and "OR" comprised essential and optional compounds, respectively, for the specific diagnosis. The third group, "NO", included compounds which must be absent to reach a diagnosis. We compiled data of MU values and mass spectrum of 130 kinds of index metabolites, and tested the usefulness of this system by analysis of 74 patients with 19 kinds of diseases. In all cases, at least a correct diagnosis could be found among the disease names outputted. We have successfully applied this to a pilot neonatal screening by GC/MS in our regional area, and acylglycine analysis by the stable isotope dilution method with tert-butyldimethylsilyl derivatization. With our system, many people can attend for screening programs using GC/MS.

Amino Acid Metabolism, Inborn Errors↗
PubMed2002

Automated time-resolved immunofluorometric assay for Toxoplasma gondii-specific IgM and IgA antibodies: study of more than 130,000 filter-paper blood-spot samples from newborns.

BACKGROUND: To screen for congenital toxoplasmosis, we developed a time-resolved immunofluorometric assay for the simultaneous detection of Toxoplasma gondii-specific IgM and IgA in filter-paper samples collected from newborns 4-7 days after birth. METHODS: The assay was performed on the AutoDELFIA, and results were calculated based on the ToxoM WHO Third International Reference Serum. Comparison with an in-house mu-capture immunoassay was carried out retrospectively on filter-paper samples from children with confirmed congenital toxoplasmosis. Prospectively the assay was compared with a mu-capture immunoassay on 68 394 samples and a commercially available assay on another 69,467 samples. Before serum was requested from the newborn, positive samples were tested for IgA and IgM separately and in an IgM-immunosorbent agglutination assay developed for filter-paper samples. RESULTS: Intra- and interassay variations (CVs) were 8% and 16%, respectively. The cutoff of 5 units/mL produced a 0.5% retest rate. The assay detected 13 of 18 (72%) samples from newborns diagnosed with congenital toxoplasmosis in the retrospective study. Prospectively, the assay identified 24 newborns who were later diagnosed with congenital toxoplasmosis. Results for all 24 cases were positive by the respective comparison method. No cases were detected solely by the IgA antibodies in the sample. CONCLUSION: Neonatal screening for congenital toxoplasmosis can be automated by use of purified europium-labeled antigen for detection of T. gondii-specific IgM and IgA eluted from filter-paper samples.

Animals↗
PubMed1997

Neuropsychological development in a child with early-treated congenital hypothyroidism as compared with her unaffected identical twin.

OBJECTIVE: Neonatal screening for congenital hypothyroidism (CH) prevents the serious neuropsychological features of CH, but the question remains whether intelligence and motor skills of CH children treated early are completely normal. DESIGN: In this report we describe the rare case of two genetically identical twins, only one of whom was affected by CH due to thyroid agenesis. L-Thyroxine (9 microg/kg body weight/day) therapy was initiated at 27 days of age and was adequate throughout the follow-up. METHODS: Neuropsychological evaluation was performed on the twins in parallel from 3 months to 8 years of age. RESULTS: The CH twin (NB) did not show major neuromotor impairments but, compared with the unaffected twin (EB), she had a slight delay in postural/motor achievements and in language development that completely disappeared at 8 years of age. On standardised tests of intelligence, NB was indistinguishable from control children but, compared with her twin, she had lower IQ scores in most testing occasions up to 7 years of age (NB = 108 vs EB = 115). School achievements of NB did not significantly differ from those of her classmates but, compared with her twin, she scored worse in writing, mechanical reading, verbal memory, and possibly in arithmetic. CONCLUSIONS: Because the twins were genetically and phenotypically identical, were raised in the same environment, and received a similar education, it is concluded that hypothyroidism in utero and in the first neonatal month was responsible for the lower neuropsychological achievements of the CH twin. While foetal hypothyroidism is at present unavoidable, earlier diagnosis and initiation of treatment in neonates with CH are important and highly recommended.

Aging↗
PubMed1991

Early detection of hearing impairment: what role is there for behavioural methods in the neonatal period?

A survey of the use of behavioural methods for neonatal hearing screening in 1985 (1) concluded that the future for automated methods was quite promising. Since then several studies have assessed the two main automated behavioural tests: the Auditory Response Cradle (ARC) and the Crib-o-Gram (COG). As a screen targeted at neonatal intensive care unit (NICU) babies and other high risk groups (at present the most cost-effective form of neonatal hearing screening), the ARC is shown to have low sensitivity, even for severe hearing impairments, and the COG has an unacceptably low specificity. Any future for behavioural testing during this period must therefore rely on new implementations flowing out of a fundamental understanding of (a) the way in which neonates respond to sound and (b) the ways in which a behavioural test might complement screening with Auditory Brainstem Responses (ABR) or Evoked Oto-acoustic Emissions (EOAE). A clearer understanding of the relative benefits of detecting different degrees of hearing impairment at birth in both the NICU population and the unrestricted population is urgently needed. To determine what role should be played by specific screening programmes such benefits need to be balanced against the total costs of screening assessment and rehabilitation, in which false positives (low specificity) play a large part.

Acoustic Stimulation↗
PubMed2004

Effect of long-term L-thyroxine treatment on bone mineral density in young adults with congenital hypothyroidism.

OBJECTIVE: To evaluate whether long-term L-thyroxine therapy in young adults with congenital hypothyroidism may affect bone mineral density (BMD). DESIGN: Thirty-seven subjects with congenital hypothyroidism, detected by neonatal screening and longitudinally followed from the time of diagnosis and treatment (26+/-4 days) up to the age of 17.8+/-1.0 years, were studied. METHODS: Spinal (L2-L4) BMD, measured by dual-energy X-ray densitometry, and bone quality, measured as amplitude-dependent speed of sound (Ad-SoS) by quantitative ultrasound, were evaluated. RESULTS: Z-score mean values (+/-s.d.) of BMD (-0.3+/-0.7) and Ad-SoS (-0.7+/-1. 1) were slightly below the average but within the normal range. Ad-SoS resulted in a z-score below -1 in 38% of patients as compared with BMD which resulted in a z-score below -1 in only 13.5% of subject. No significant differences were observed between males (BMD, -0.3+/-0.7; Ad-SoS, -0.9+/-1.0) and females (BMD, -0.3+/-0.7; Ad-SoS, -0.5+/-1.2) or when dividing patients on the basis of aetiological defects; ectopic gland (BMD, -0.3+/-0.6; Ad-SoS, -0.8+/-0.9), athyreosis (BMD, -0.3+/-0.9; Ad-SoS, -0.8+/-1.0) and eutopic gland (BMD, -0.3+/-0.8; Ad-SoS, -0.4+/-1.3). No significant relationships were observed between BMD or Ad-SoS z-score and hormonal status or L-thyroxine dosages at the time of the study or during the pubertal period. CONCLUSIONS: The careful monitoring of serum thyroid-stimulating hormone and adjustment of l-thyroxine dosage avoided the significant deleterious effects of prolonged L-thyroxine replacement therapy on bone tissue in adolescents and young adults with congenital hypothyroidism treated from the neonatal period.

Absorptiometry, Photon↗
PubMed1985

Direct solid-phase radioimmunoassay for screening 17 alpha-hydroxyprogesterone in whole-blood samples from newborns.

We describe a direct, solid-phase RIA for 17 alpha-hydroxyprogesterone (17-OH-P) that we are using to screen neonates for congenital adrenal hyperplasia. Phosphate buffer containing danazol and anti-17-OH-P is placed in tubes coated with antibody to IgG. The tubes also contain standards, controls, or blood samples on filter paper discs 3 mm in diameter. 125I-labeled 17-OH-P is added to each tube. The mixture is vortex-mixed and incubated overnight. The fluid and disc are removed, the radioactivity remaining in the tubes is counted, and the amount of 17-OH-P per disc is calculated by using a log-logit transformation of the standard curve. Results compare favorably with those by two extraction assays. Inter- and intra-assay CVs were less than 11% and less than 9%, respectively. Sensitivity was 2 pg per assay tube. There is no significant cross reactivity with structurally related steroids at their physiological concentrations. Analytical recovery of added 17-OH-P averaged 104%. 17-OH-P in whole blood spotted on filter paper is stable for at least six months.

17-alpha-Hydroxypregnenolone↗
PubMed1982

Immunoassay of blood spot TSH; development of a rapid two-site immunoradiometric assay and comparison with radioimmunoassay as a screening method for neonatal hypothyroidism.

The development of a two-site immunoradiometric assay (IRMA) for thyrotropin (TSH) eluted from dried blood filter paper discs is described and compared with a conventional TSH radioimmunoassay (RIA) as a screening procedure for neonatal hypothyroidism. The iodinated antibody for the IRMA is prepared by a reproducible four step procedure. Specific antibody is selected from whole TSH antiserum with TSH covalently linked to microparticulate cellulose, iodinated as the solid phase antigen-antibody complex, and eluted by repeated changes in pH from 3 to 10. The pooled eluted material is finally purified by Sepharose 6-B gel chromatography to recover labelled monomeric anti-TSH IgG. Solid phase antibody for the IRMA is prepared by covalently linking a partially purified IgG fraction of TSH antiserum to carbonyldiimidazole-activated microparticulate cellulose. Typically yields of 2-3 mg protein per 100 mg cellulose (2-3%, w/w) are obtained. The two-site IRMA involves a primary incubation of excess labelled TSH antibody and the blood disc for 16-18 h at pH 8 and a secondary 3 h incubation under agitation, with solid phase TSH antibody. Bound and free fractions are separated by a semi-automated washing procedure. Compared with the conventional RIA, the two-site IRMA is quicker (results available within 24 h compared to 3 days for RIA), more precise at clinically important TSH levels (25-30 mU TSH/l), and more sensitive (detection limit less than w mU/l compared to 6 mU/l for RIA). The two-site IRMA is technically simpler than RIA and has proved rugged in routine practice. TSH levels in filter paper blood spots prepared from whole blood with levels of standard TSH (MRC 68/38) within the range 6 to 200 mU/l, correlated well in both assays (r = 0.969). Recoveries of 98% and 104% were demonstrated for the two-site IRMA and RIA, respectively. It is concluded that the two-site TSH IRMA has advantages over conventional RIA in speed, sensitivity, precision and ruggedness and can be recommended as an efficient screening procedure for neonatal hypothyroidism.

Autoanalysis↗