ABSTRACT
Significant changes in thyroid hormones occur during the first weeks after birth. We assessed the degree of changes in thyroid-stimulating hormone [TSH] and total thyroxin [T4] concentrations in neonates screened seven days after the first high serum TSH levels, just before starting treatment. This prospective study was carried out on newborns referred for their high TSH concentrations on heel blood spot in hypothyroidism screening tests [5- 20 miu/ml], between December 2009 and December 2010. First, serum TSH and T4 were assessed by radioimmunoassay. One week later, in neonates with the first serum TSH >/= 10, serum TSH and T4 were rechecked before starting treatment. Any definite decision to continue treatment was based on the second test results. The results showed a significant decrease in serum TSH level after one week [p<0.01]. Serum T4 level increased significantly in neonates with the first serum TSH >/= 40 [p<0.05], while no significant difference was observed in other infants with the first serum TSH<40. Incidence rate of Congenital Hypothyroidism [CH] reduced from 1/329 to 1/851, during the study. It may be appropriate to repeat serum T4 and TSH concentrations after 2 and 4 weeks in neonates with normal serum T4 but elevated TSH. In the case of persistent TSH elevation, the infant should be treated as this can prevent unnecessary treatments, family stress and iatrogenic hyperthyroidism in these patients
ABSTRACT
Sensory signals and intrinsic activity of the neuronal circuits deeply influence on developing the sensory systems in early life. Light deprivation of animals is known as an established method in assessment of environmental signals in development of the nervous system. In this experimental study eighteen male rats at 75 days of postnatal age were used. The animals were divided in two groups, one reared in a cycle of 12light/12dark [light reared-LR] and the other keep in darkness since birth through experiment [Light deprived- LD]. The animals were trained in a Morris water maze for spatial memory. They must navigate the maze until finding a platform hidden 1 cm below of water. Then, the time required and the distance spent to find the platform were measured for assessment of the animal behavior. Each animal was given 4 trials/day and the experiment lasted for 6 days. This stage was followed by probe and postprobe tests to evaluate how the learning is consolidated. The results indicated that, compared to their LD counterparts, the LR group was superior in finding the platform where they required a noticeable shorter time to hit the platform [p<0.009]. Also, animals in the LR group steered a shorter distance to find the target than did the LD animals [p<0.034]. While the two groups elicited a considerable difference during the first half of the experiment both LR and LD rats demonstrated a similar behavior over the second half of the study. The light deprivation negatively influences the spatial navigation in water maze so that the visually deprived rats show less ability in searching the maze based on the spatial cues