Hypothyroidism

Question 1

What are the causes of Primary Hypothyroidism?

Answer 1

Thyroiditis
-Hashimoto's 
-Postpartum
Iodine Def/Excess
Radiation
Surgery
Infiltrative
Drugs

Question 2

What are the causes of Secondary Hypothyroidism?

Answer 2

Surgical (excision of adenoma)
Infiltrative/mets
Rad therapy
Apoplexy
Low T4 with innap. low TSH

Question 3

What are the clinical Features of Hypothyroidism?

Answer 3

Hair loss, brittle nails
non-pitting edema (GAGs)

Pericardial Effusion, edema
Bradycardia

Decreased GI Motility , Constipation
Ascites

Menstrual Abn
Dec Fertility

Depression, fatigue
Dec Reflexes
Carpel Tunnel Synd

Hyperchol, HyperTRG
Weight Gain

Question 4

What are the lab levels seen in Hashimoto’s Thyroiditis?

Answer 4

ELevated TSH +/- Low T4

Usually TPO Ab are elevated however not required for diagnosis

Question 5

What are the main sources of Iodine in I induced Hypothyroidism?

Answer 5

Radiocontrast for CT
Amiodarone
Supplements

Question 6

What are the Tx of Hypothyroidism?

Answer 6

Replacement of Levothyroxine (T4)
about 1.5mcg/kg/day
Start low in older, cardiac Pt
Indicated if TSH > 10
Usually not necessary if TSH

Question 7

What are the special considerations of Hypothyroid Tx in Pregnancy?

Answer 7

Thyroid hormone needs increase throughout pregnancy

may need 150% of original dose by end of preggo

Question 8

WHat are the Dangers and considerations in Myxedema Coma?

Answer 8

Acute Medical Emergency
-Mental Status changes
-Hypothermia
-Hypoglycemia
-Resp Failure, Hypotension, BrCa
Older women
Precip by infection, CVA, MI

Question 9

What is the Tx of Myxedema Coma?

Answer 9

Supportive MEasures
Fluid Therapy
IV thyroxine replacement
Treat cause
Hydrocortisone 100mg

Question 10

WHat are the considerations in Thyroid Cancer?

Answer 10

Usually surgically hypothyroid
T4 used to replace endogenous production
Used to suppress TSH to goal

Question 11

WHat are the considerations in Secondary Hypothyroidism?

Answer 11

Pituitary or Hypothalamic insult
TSH no longer reliable
Free T4 used to guide dose adjustments

Question 12

What is generally not reccomended in Hypothyroid therapy?

Answer 12

Using T4 to 
-Shrink nodules
-Lose Weight
-Treat Depression
-Lower Cholesterol
May lead to iatrogenic hyperthyroidism

Question 13

What factors increase TBG?

Answer 13

Estrogen (pregnancy, BCP)
Congenital
(less active Thyroid Hormone)

Question 14

What factors decrease TBG?

Answer 14

Systemic Illness
Glucocorticoids
(More active Thyroid Hormone)

Question 15

What is the best test of thyroid function?

Answer 15

TSH (less prone to fluctuations)

Inversely Proportional to thyroid function

Question 16

What are other tests for the Thyroid? What do they tell you?

Answer 16

Thyroperoxidase Ab: Thyroiditis, Hypothyroid
Thyroglobulin & Thyroglob Ab:
Thyrotropin Rec Ab/TS Ab: Graves’
Radionucleide Scans: Funct activity of the thyroid