230 likes | 405 Views
Good Morning!!. Morning Report Tuesday, September 13th. Common Causative Agents: Procainamide Hydralazine Penicilliamine (But you can also see drug-induced SLE with phenytoin , methimazole and many other medications). Hypothyroidism. Congenital Hypothyroidism. Why worry?
E N D
Good Morning!! Morning Report Tuesday, September 13th
Common Causative Agents: • Procainamide • Hydralazine • Penicilliamine • (But you can also see drug-induced SLE with phenytoin,methimazole and many other medications)
Congenital Hypothyroidism • Why worry? • T4 is critical to the myelinization of the CNS during the first 3 years after birth • Most preventable cause of potential intellectual disability (so you don’t want to miss it!!!)
Definition • In healthy newborns: • Abrupt rise in TSH within 30-60 mins of delivery stimulates T4 secretion • TSH levels peak early, while T4 levels peak 24-36h after delivery • In premature newborns: • Smaller increases in TSH lower T4 values • Immaturity of the hypothalamic-pituitary axis • Concurrent non-thyroid illnesses
Epidemiology • 85% cases sporadic, 15% hereditary (AR) • Incidence 1:4000 infants • More common in Hispanics and Caucasians • More common in females (2:1) • More common in twins • Longer the diagnosis and treatment are delayed, the lower the IQ
*Etiology • Thyroid dysgenesis (most common) • Ectopic thyroid • Thyroid aplasia • Thyroid hypoplasia • Inborn errors of thyroxine synthesis • Defects in thyroid peroxidase activity • Abnormalities in iodine transport • Production of abnormal thyroglobulin • Iodotyrosinedeiodinase deficiency
*Etiology (con’t) • Maternal antibody-mediated • Central • Won’t be detected on NBS using TSH screening • Iodine deficiency/ Iodide excess • Transient • Non-thyroid illness (euthyroid-sick syndrome)
*Symptoms and Signs Birthweight and length normal (? Increased HC) Open posterior fontanelle Umbilical hernia Lethargy/hypotonia Hoarse cry Feeding problems Constipation Macroglossia Dry skin
Laboratory Testing • Newborn Screen • Most states use initial T4 testing with f/u TSH • Initial labs • Free T4 • Total T4 • T3 • TSH • In all forms of congenital hypothyroidism, serum T4 is low and TSH is elevated, except for central hypothyroidism where both T4 and TSH are low
*Management • Goals are normal growth and good cognitive outcome • Levothyroxine • 10-15 mcg/kg/day • 50mcg/day recommended for all term and full-sized infants • 10-15mcg/kg for preterm infant using the higher range for infants with lower T4 • Tablets only • Do not mix with soy formula or any preparation with iron or calcium
*Management (con’t) • Quicker correction is better! • Goal to keep serum TT4 or fT4 in upper half of normal range for age and have normal TSH • Serum T4 (or free T4) and TSH • At 2 and 4 weeks after initiation of therapy • Q1-2 mos during 1st 6 postnatal mos • Q6mos from 6mos-3yrs • Q6-12 mos until growth is complete
*Prognosis • Babies born with congenital hypothyroidism who are appropriately treated within the first 2-6 postnatal weeks grow and develop NORMALLY! • Children who are treated inadequately in the first 2-3 years after birth have IQs below those of unaffected children • 6-15 point lower IQ in the severely affected • Even if IQ was not affected, difficulties with gross/fine motor coordination, ataxia, altered muscle tone, strabismus, decreased attention span and speech
Acquired Hypothyroidism • Onset after 6 mo old • Caused by failure of the hypothalamic-pituitary-thyroid axis • Primary: thyroid • Secondary: pituitary • Tertiary: hypothalamus
Epidemiology • Most cases are sporadic • Only 10-15% are inherited • More common in females (2:1) • Hashimoto thyroiditis most common cause • May occur by itself or in association with other AI diseases • Occurs more commonly in patients with Down syndrome or Turner syndrome
*Causes of Acquired Hypothyroidism Primary Secondary/ Tertiary Craniopharyngioma Neurosurgery Cranial irradiation Head Trauma • Hashimoto (AI) thyroiditis • Postablation • Irradiation to the neck • Medications • Iodine deficiency • Late onset congenital hypothyroidism
*Signs and Symptoms • Decline in linear growth • Fatigue • Constipation • Cold intolerance • Decline in school performance • Weight gain • Irregular menstrual periods • Dry skin • Hair loss
*Lab Evaluation ~Use of U/S and thyroid scan in diagnosis usually not warranted.
Management • Levothyroxine • Age 6-12 mos: 5-8 mcg/kg • Age 1-3 years: 4-6 mcg/kg • Age 3-10 years: 3-5 mcg/kg • Age 10-18 years: 2-4 mcg/kg • Serum free T4 and TSH levels q3-6 mos • Goal: fT4 in mid-normal range with TSH nml
Prognosis • Growth may not recover if: • Hypothyroidism longstanding • Diagnosed during puberty • Cognitive/ neurologic deficits unlikely if onset is after 2-3 yo
Other entities… • Thyroid-binding globulin deficiency • Low TT4, low or normal serum fT4, normal TSH • Normal free T4 by equilibrium dialysis • Corrects for low TBG • Low TBG • Thyroid hormone resistance • Normal labs with clinical features of hypothyroidism
Thanks for your attention! Noon Conference: Neonatal Surgical Emergencies, Dr. Mumphrey!!!