1. Study the pattern of congenital hypothyroidism in newborns after positive newborn screening results.
2. Assess the characteristics of the cases (permanent congenital hypothyroidism and transient neonatal hyperthyrotopinemia).

Thyroid hormone is essential for normal somatic growth and neurological development in infants and children. Deficiency of thyroid hormone in the first 2 years of life results in congenital hypothyroidism (CH). CH manifests by mental retardation and growth retardation in newborn.

Newborn screening (NS) for CH aims to early diagnosis and treatment of hypothyroidism. CH occurs about one in 3000-4000 infants . CH is suspected in neonatal screening when capillary thyroid-stimulating hormone (TSH) concentrations are elevated (>15 mU/L in Germany). The diagnosis is confirmed by measuring venous TSH and free thyroxine levels (FT4) concentrations before the start of treatment.

CH can be classified into permanent or transient congenital hypothyroidism (TCH). While CH is a persistent deficiency of thyroid hormones that requires lifelong treatment, TCH is a temporary deficiency that reverts to normal concentrations with proper medical management, usually during the first few months of life and not after the age of 3 years.

Transient neonatal hyperthyrotropinemia (TNH) is defined as temporary postnatal elevation of TSH levels (10 mIU/L-20 mIU/L) with normal FT4 levels but TSH returning to normal (<10 mIU/L) when measured at 14 d of life. It is important to recognize TNH as these newborns have a higher risk of developing permanent hypothyroidism with repercussion on developmental status. Thus, we aimed at evaluating the neonatal and maternal factors associated with TNH . So that, identifying these factors may be considered as an appropriate strategy to prevent these possible disorders. There is a gap in studying the prevalence and the predictors of transient neonatal hyperthyrotropinemia particularly in Assiut Governorate.

Inclusion Criteria:

• For the case series study: all positive newborns cases with raised TSH level (the confirmed raised TSH cases after thyroid hormone screening) within one month after birth will be taken during one year.
• For the secondary outcome to study the predictors of permanent congenital hypothyroidism and transient neonatal hyperthyrotropinemia, control group with matched age and gender with normal TSH at birth according to the neonatal TSH screening will be taken. Matched normal neonates will be selected to be compared with permanent congenital hypothyroidism cases and transient neonatal hyperthrotropinemia cases.

Exclusion Criteria:

• Cases that refused to participate in research.
• Cases that missed for follow up.

Cases: Newborn with TSH (the confirmed raised TSH cases after thyroid hormone screening) within one month after birth, both transient neonatal hyperthyrotropinemia cases and permanent congenital hypothyroidism included in the study.