Thyroid diseases in children and adolescents include acquired or congenital conditions, including genetic disorders either isolated or part of a syndrome. Briefly, we will review the physiology and pathophysiology of the thyroid gland and its disorders. The aim of this chapter is to describe genetic abnormalities of the thyroid gland.

Case report 19 months old African American boy with nonsignificant past medical history presented with inability to walk, hypotonia chewing difficulties and speech delay. Initial laboratory evaluations demonstrated serum hyponatremia of 120-129 mEq/dl, low serum osmolality 261 mosm/kg (normal serum osmolality 275-295 mosm/kg) with inappropriately high urine osmolality 445 mosm/kg) (normal urine osmolality 300-1000 mosm/kg). Blood work for thyroid, adrenal, and pituitary function was unremarkable. Vasopressin level of 2.4 pg/ml (normal 0.0 - 4.7 pg/mL) did not support the diagnosis of Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). Fludrocortisone challenge test ruled out aldosterone deficiency with insufficient decrease in urine sodium and no response in serum sodium. Renal ultrasound and brain MRI were normal. Genetic testing revealed AVPR2 X-linked mutation c.409C>T p.R137C, consistent with nephrogenic syndrome of inappropriate antidiuresis (NSIAD). The patient was discharged on sodium chloride tablets 2g every 8 hours and remained stable, asymptomatic. One month after discharge patient showed significant neurological improvement. Discussion Sodium is known to play a significant role in growth and maturation of the whole body, especially of the nervous system. Moderate (120-129 mEq/L) to severe (<120 mEq/L) hyponatremia can present with nausea, malaise, headache, lethargy, motor and speech delay, seizures and even death due to brain herniation. Normal fluid and electrolyte balance is achieved by the thirst mechanism and free water excretion in kidneys. This is mediated by Vasopressin, which acts through V2R receptor in distal renal collecting duct. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of hyponatremia. Reset osmostat syndrome with a congenitally low serum osmolality threshold is one of the rare disorders on the differential. Hereditary nephrogenic syndrome of inappropriate antidiuresis is very rare mutation in vasopressin receptor, which clinically resembles SIADH except for normal/low vasopressin levels in set of hyponatremia. It causes gain of function and inappropriately high water retention. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

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Childhood obesity is highly prevalent among certain populations of New York. This cross-sectional pilot study examined the associations between parental attitudes about outdoor activities and body mass index (BMI). A questionnaire was distributed among parents of 1 to 13 aged children at ambulatory pediatric clinics. Of 104 children included in the study 57 were of normal weight and 47 were overweight or obese. Most parents of children with BMI <85% reported frequent playground utilization, considered longer hours to spend outside on weekdays, reported a larger total temperature range for outdoor playground utilization and a lower tolerable minimum temperature compared to parents of children with BMI ≥85%, p < .05. Only having a parent born outside of the United States remained a significant predictor of overweight and obesity in the final model. Parents of children with BMI < 85% are more willing to spend time outdoors, regardless of weather. Immigrant parents are protective against overweight.