Congenital hypothyroidism (CH) is defined as thyroid hormone deficiency present at birth. Babies with CH who are not identified and treated promptly develop severe mental retardation. Most of the babies with CH do not manifest the typical known signs and symptoms of hypothyroidism, and this is most likely due to transplacental passage of some maternal thyroid hormone in addition to some residual neonatal thyroid function, as might be seen with thyroid hypoplasia, an ectopic gland, or mild dyshormonogenesis. Screening for CH has enabled the virtual eradication of the devastating effects of mental retardation due to sporadic CH in most developed countries of the world. CH is classified into permanent and transient forms, which in turn can be divided into primary, secondary, or peripheral etiologies. Permanent CH refers to a persistent deficiency of thyroid hormone that requires life-long treatment. Transient CH refers to a temporary deficiency of thyroid hormone that is discovered at birth but recovers to normal in the first few months or years of life. In the last several decades, there have been exciting advances in our understanding of fetal and neonatal thyroid physiology. In addition, advances in molecular biology have helped in understanding the early events in thyroid gland embryogenesis, mechanisms of thyroid action in the brain, the molecular basis for many of the inborn errors of thyroid hormonogenesis, and thyroid hormone action. However, many questions and challenges are still not answered. For example, the increasing numbers of surviving small and premature neonates with abnormalities in thyroid function need definite diagnostic criteria and whether they require medical therapy. Another challenge is the dilemma of finding the best screening methodology that is sensitive and cost effective.

Objective To assess the performance of the use of umbilical cord blood for screening of primary congenital hypothyroidism in the Saudi Aramco Medical Services Organization newborn thyroid screening programme. Methods Umbilical cord blood total thyroxin (CB-TT4) was measured. In samples with low T4 concentrations, an additional measurement of cord blood thyroid-stimulating hormone was made. Results A total of 96,015 newborn infants were screened in the period January 1990 -December 2007. Twenty-six cases of primary congenital hypothyroidism, six cases of transient hypothyroidism and 13 cases of central hypothyroidism were detected. This method of screening resulted in 100% sensitivity and 98% specificity (95% CI 84 -100, and 95% CI 98-98.2, respectively). However, there was a high mean recall rate of 1.9%. Conclusion The use of CB-TT4 is a valid screening strategy for primary congenital hypothyroidism. It meets the metabolic screening demands of early discharge policy and guarantees screening all newborns delivered in the hospital.

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The diagnosis of spontaneous haemophilia A with severe antihaemophilic globulin deficiency (less than 1%) was established in an 11-year-old girl with a normal female chromosomal pattern. Coagulation studies proved that the proposita is the offspring of a normal father with negative history for bleeding disorders and a normal mother who had an antihaemophilic globulin concentration of 200%. Family history revealed no bleeding disorder in 3 successive generations of the maternal side. This together with AHF activity exceeding slightly AHF-like antigen concentration provides good evidence against the carrier state of the mother. The possible mechanisms through which spontaneous haemophilia may occur in a genotypically normal female are discussed.

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