USMLE Internal Medicine Review 10 05 Neonatal Hypothyroidism

USMLE Internal Medicine Review 10 05 Neonatal Hypothyroidism

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Let’s start our USMLE Review with Hypothyroidism and Hyperthyroidism from the Gold Standard USMLE Foundations of Medicine Audio Review program.

 

Play USMLE Audio MP3 10 05 Neonatal Hypothyroidism Below

 

Begin 10 05 Neonatal Hypothyroidism Transcription

What is another term for Neonatal hypothyroidism, starting with C?

  • Cretinism

Neonatal hypothyroidism may result from failure of the thyroid to descend properly during embryonic development.

Where is the thyroid originally located?

  • The thyroid descends from its origin at the base of the tongue to its usual site in the lower anterior neck.

What results from this failure of the thyroid to descend properly?

  • This results in an ectopic thyroid gland which functions poorly.

Cretinism, originally occur primarily in geographical locations with which two characteristics?

  • Cretinism originally occurs primarily in regions of low iodide intake and endemic goiter.

In the U.S. have neonatal screening programs revealed white or black infants more prone to neonatal hypothyroidism?

  • The incidence of neonatal hypothyroidism in white infants was revealed to be about 1 in 5,000, while in black infants it was only 1 in 32,000.

Placental transfer to the embryo from a mother with Hashimoto’s thyroiditis may result in what thyroid abnormality?

  • Agenesis of the thyroid gland or athyroidic cretinism.

Student doctor please pause the tape and summarize for the incidence of neonatal hypothyroidism, along with a complication from Hashimoto’s thyroiditis in the mother.

  • Neonatal hypothyroidism or cretinism may result from failure of the thyroid to descend properly during embryonic development from its origin at the base of the tongue to its usual site in the lower anterior neck.  This results in an ectopic thyroid gland which functions poorly. Cretinism originally occurs primarily in regions of low iodide intake and endemic goiter. In the US, neonatal screening programs have revealed white infants more prone to neonatal hypothyroidism than black infants by a ratio of about 6 to 1. Placental transfer to the embryo from a mother with Hashimoto’s thyroiditis may result in agenesis of the thyroid gland or athyroidic cretinism.

Pause the tape and do your best to describe the typical signs and symptoms profile of the infant with neonatal thyroidism.

  • Hypothyroid infants may suffer from all or some of the following: mental retardation and retardation of bone maturation, short stature with muscle weakness, respiratory difficulties, cyanosis, jaundice, poor feeding, a hoarse cry, puffy appearance of the face and hands, protuberant abdomen sometimes with umbilical hernia, and frequently deaf mutism and neurological signs of pyramidal and extrapyramidal track abnormalities.

And absence of which two structural epiphysis normally present in infants above 2500 grams also strongly suggest neonatal hypothyroidism?

  • The absence of the proximal tibial and distal femoral epiphysis suggest the diagnosis.

Student doctor please pause the tape and repeat the signs and symptoms profile of the hypothyroid neonate.

  • Hypothyroid infants may suffer from all or some of the following: mental retardation and retardation of bone maturation, short stature with muscle weakness, respiratory difficulties, cyanosis, jaundice, poor feeding, a hoarse cry, puffy appearance of the face and hands, protuberant abdomen sometimes with umbilical hernia, and frequently deaf mutism and neurological signs of pyramidal and extrapyramidal track abnormalities. The absence of the proximal tibial and distal femoral epiphysis also strongly suggests the diagnosis of hypothyroidism in infants.

What kind of inherited hormonal defects can induce neonatal hypothyroidism and goiter?

  • Inherited defects in thyroid hormone biosynthesis.

Rarely causes of neonatal hypothyroidism involve administration during pregnancy of which three agents?

  • (Just list them please) iodides, antithyroid drugs or radioactive iodine.

Introduction of which two routine screenings for newborns has been a major factor in the early diagnosis of neonatal hypothyroidism?

  • Introduction of TSH and T4 screenings for newborns.

Serum T4, under how many µg in infants is indicative of neonatal hypothyroidism?

  • Serum T4 under 6µg per dL.

And TSH above how many micro units per mL is indicative?

  • Serum TSH above 30micro units per mL.

If one or both of these readings is indicative diagnosis of neonatal hypothyroidism can then be confirmed by what radiological evidence?

  • Radiological evidence of retarded bone age.

Student doctor please pause the tape and remark on inherited defects, rare causes, and screening tests for neonatal hypothyroidism.

  • Inherited defects in thyroid hormone biosynthesis can induce neonatal hypothyroidism and goiter. Rarer causes of neonatal hypothyroidism involve administration during pregnancy of iodides, antithyroid drugs or radioactive iodine. Introduction of routine T4 and TSH screenings for newborns has been a major factor in the early diagnosis of neonatal hypothyroidism. Serum T4 under 6µg per dL or TSH above 30micro units per mL in infants is diagnostic. If one or both of these readings is significant, diagnosis of neonatal hypothyroidism can then be confirmed by radiological evidence of retarded bone age.

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