Detection And Treatment Of Congenital Hypothyroidism PdfDownload Free Software Programs Online12/12/2016 Newborn Screening for Congenital Hypothyroidism. Abstract. Newborn screening (NS) for congenital hypothyroidism (CH) is one of the major achievements in preventive medicine. Most neonates born with CH have normal appearance and no detectable physical signs. Hypothyroidism in the newborn period is almost always overlooked, and delayed diagnosis leads to the most severe outcome of CH, mental retardation, emphasizing the importance of NS. Blood spot thyroid stimulating hormone (TSH) or thyroxine (T4) or both can be used for CH screening. The latter is more sensitive but not cost- effective, so screening by TSH or T4 is used in different programs around the world. Screening of newborns for congenital hypothyroidism guidance for developing programmes international atomic energy agency vienna, 2005.Thyrotoxic myopathy (TM) is a neuromuscular disorder that develops due to the overproduction of the thyroid hormone thyroxine. Also known as hyperthyroid myopathy, TM is one of many myopathies that lead to muscle weakness and. Hypothyroidism is a common endocrine disorder that mainly affects women and the elderly. This article outlines the aetiology, clinical features, investigation and management of hypothyroidism. Dental Health Considerations & Solutions in Patients with Turner Syndrome Robert Korwin, D.M.D. Post Graduate Certificate in General Practice Master, Academy of General Dentistry Master, International College of Oral. TSH screening was shown to be more specific in the diagnosis of CH. T4 screening is more sensitive in detecting especially those newborns with rare hypothalamic- pituitary- hypothyroidism, but it is less specific with a high frequency of false positives mainly in low birth weight and premature infants. The time at which the sample is taken may vary. In the majority of the centers, blood is obtained from a heel prick after 2. TSH due to the physiological neonatal TSH surge that elevates TSH levels and causes dynamic T4 and T3 changes in the first 1 or 2 days after birth. Early discharge of mothers postpartum has increased the ratio of false positive TSH elevations. Although transient hypothyroidism may occur frequently, all these infants should be treated as having CH for the first 3 years of life, taking into account the risk of mental retardation. A reevaluation after 3 years is needed in such patients. Hypothyroidism can be induced by various diseases. An autoimmune cause accounts for approximately 90% of adult hypothyroidism, mostly due to Hashimoto's disease. The majority of Hashimoto patients are women aged between 20 and. The goal of initial therapy in CH is to minimize neonatal central nervous system exposure to hypothyroidism by normalizing thyroid function, as rapidly as possible. Conflict of interest: None declared. Keywords: Neonatal screening, congenital hypothyroidism, iodine deficiency. INTRODUCTIONCongenital hypothyroidism (CH) is the commonest treatable cause of mental retardation. It is one of the most common disorders related to mental impairment and growth retardation in newborns. In many countries, neonatal thyroid screening programs are performed for early diagnosis and treatment of hypothyroidism. CH is usually sporadic and occurs in one in 3. Most infants with CH are normal at birth and show no signs, emphasizing the importance of screening programs in early detection of CH (1,2). Newborn screening (NS) for CH is one of the major achievements of preventive medicine. Although since 1. CH has been resolved in developed countries by the implementation of NS, the same cannot be said for developing countries that still have no NS programs for CH (2,3). Since diagnosis based on clinical findings is delayed in most instances because of few symptoms and signs, hypothyroidism in the newborn period is almost always overlooked, and delayed diagnosis leads to the most severe outcome of CH, namely, mental retardation. In a Danish study (4) conducted on infants born between 1. In the remainder of the infants, the diagnosis was delayed to the 3rd and 4th years of life. In a retrospective analysis of 1. CH from Turkey (5), the mean age at diagnosis was reported to be 4. The first CH screening was performed by Dussault (6,7), in Quebec- Canada in 1. They detected 7 hypothyroid infants among 4. The high frequency of false positives delayed the diagnosis and increased the cost, and they therefore devised cut- offs values to be used for recall. Thyroid hormone and thyroid- stimulating hormone (TSH) levels were assessed in the recalled group of babies. In the meantime, radioactively labeled antibodies for determining thyroxine (T4) in dried blood spots were introduced regionally in the USA and in Europe. Screening programs for CH went parallel with screening programs of phenylketonuria. In the initial report by Dussault et al (8), the method was recommended as a confirmatory test, knowing that it would miss cases with hypothalamic- pituitary hypothyroidism, which they reported to constitute 1. In 1. 97. 6, Walfish (9) reported in the Lancet that cord blood TSH measurements had greater sensitivity and specificity as compared to cord blood T4 and spot blood (collected on 3 to 4 day old newborns) T4 results and that both false positives and costs were higher in the T4 method. This same author also suggested routine T4 supplemented by TSH estimation be used in mass screening. Although more sensitive, screening by T4 and TSH together is not cost- effective, therefore, mostly TSH, and rarely T4 screening, is used around the world. In Europe, TSH screening is preferred, whilst some centers in the USA prefer primary T4 testing supplemented by TSH (1. The recall rate for primary hypothyroidism in both approaches is 0. T4 strategy. TSH screening was shown to be more specific in the diagnosis of CH, while T4 screening was more sensitive in detecting newborns with rare hypothalamic- pituitary hypothyroidism but less specific with a high frequency of false positives mainly in low birth weight and premature babies. T4- binding globulin (TBG)- deficient babies who are euthyroid and who were not targets for NS, could also be detected by T4 screening. The Neonatal Thyroid Screening Conference held in Tokyo in 1. NS programs oriented to detect infants with elevated serum concentrations of TSH. It has been also suggested that this could be accomplished by measuring TSH in filter paper blood spot or by measuring T4 supplemented by TSH on the same blood spot of infants who have T4 values in the lower 3rd to 1. Methods. The aim of NS programs is to detect all cases with the disease as early as possible, with an acceptable cost- benefit ratio and to avoid false positive results. In recent years, more sensitive and automated methods (chemiluminescence, fluoroimmunoassay, etc.) for determining both TSH and T4 in dried blood spots have been introduced (1. These new methods have increased sensitivity and specificity in the detection of CH. However, despite the development of more accurate test programs, approximately 5% of CH cases may still be missed in any screening program. The reasons could be failure of sample collection, unsatisfactory samples, misinterpretation of samples and unsatisfactory recalls, the condition being subclinical or, as is true for programs which measure only TSH, failure to detect infants with central CH (1. The ideal time to obtain the blood spot is 3- 5 days after birth to minimize the false positive high TSH values due to the physiological neonatal TSH surge that elevates TSH levels and causes dynamic T4 and total triiodothyronine (T3) changes in the first 1 or 2 days after birth. Early discharge of mothers postpartum has increased the ratio of false positive TSH elevations from 3: 1 to 5: 1. The difficulty in screening for CH using cord blood samples is with the handling and transporting the samples, making it an impractical method for mass screening (2. In some laboratories, the threshold cut- off is adjusted based on the age of the infant when the blood spot is obtained. The cutoff for reporting an elevated TSH is a level above 2. U/m. L in most screening programs. Whichever method is used, babies whose initial TSH is > 5. U/m. L are most likely to have permanent CH, whereas a TSH level between 2. U/m. L is frequently a false positive or represents transient hypothyroidism. Transient CH is particularly common in premature infants in borderline iodine- deficient areas. In the primary TSH method (immunofluorometric method), when 1. U/m. L is used as cutoff, the recall rate is quite low (0. Iodine deficiency could increase false positives and increase recall rate up to 3% . The sensitivity of the TSH method for CH is reported to be 9. CH is reportedly increasing in the United States, possibly reflecting changes in screening methods. The TSH cutoff value has been decreased from 1. U/m. L to 5 m. U/m. L, thus adding cases that have predominantly functional disorders which impact on intellectual disability, if left untreated, remains to be determined (2. In short, NS with primary TSH method detects overt and compensated primary hypothyroidism but misses secondary/ tertiary hypothyroidism, TBG deficiency, and premature infants with very low body weight with delayed TSH surge. In primary T4 screening, performed in some states of the USA, cutoff at the 1. T4 values resulted in 1. Only 2% of cases were missed using the 2. Optimal screening requires initial T4 determination to be followed by TSH determinations in case of low T4 samples. In short, NS with primary T4 method detects overt primary hypothyroidism, secondary/tertiary hypothyroidism (1 in 5. TBG deficiency, and hyperthyroxinemia but misses compensatory hypothyroidism with subnormal T4 and elevated TSH levels as well as transient hyperthyrotropinemia when iodine deficiency is present. The reliability of the laboratories is as crucial as the reliability of the detection methods (with emphasis on sensitivity, specificity, and positive predictive value). According to the recommendations of the Working Group of Neonatal Screening of European Society for Pediatric Endocrinology (ESPE), screening should be conducted in centralized laboratories covering 1. These laboratories should participate in international control programs. In North America, it is estimated that 6- 1. CH are missed due to biological factors and screening errors (2. Results and Discussion. Hypothyroxinemia(low T4 and normal TSH)This condition occurs most commonly in premature infants and is found in 5. Screening programs that employ primary TSH analysis will miss these infants because of normal TSH levels. Often, the free T4 (f. T4) is less affected than the total T4. The reasons for the hypothyroxinemia of prematurity are complex. In addition to hypothalamo- pituitary immaturity, low TBG levels and decreased conversion of T4 to T3 exists in premature babies. Numerous studies have shown that there is a correlation between the degree of lowering of T4 and negative outcomes such as mortality and development problems.
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