Thyroid Drugs

Question 1

Hyperthyroidism Presentation

Answer 1

Diaphoresis/Sweating !! 
Heat Intolerance !!
Nervousness/Irritable !!
Hyperdefacation/diarrhea
Oligomenorrhea (infrequent)

Question 2

Hyperthyroidism Diagnosis

Answer 2

primary TSH - low
secondary TSH - way too high
T4 - high

Question 3

Hyperthyroidism Treatment

Answer 3

Referral to endocrine

Control Sx

• propanolol 10-40 QID or other BB (tremors/tachy)
• methylcellulose gtt PRN for eye exop

Treatment Choices
- RAI – FIRST LINE (over 20yo, erradicates tissue)
&raquo_space; can become hypo, then treat accordingly to hypo
&raquo_space; TSH/T4 monitor q 6 weeks
- Antithyroid Drugs (2.PTU, 1.methimazole)
&raquo_space; monitor TSH/T4, CBC, LFT
- Surgery: rare in the US common in JAP,GER

Question 4

Methimazole A/E

Answer 4

can cause fetal harm (contra in preg and lactating)

• hypothyroidism
• bone marrow suppression
• hepatoxicity
• exfoliative derm
• unexplained fever
• vasculitis
• lupus like symptoms

Question 5

Hypothyroidism Presentation

Answer 5

• slowed reflexes

Question 6

Hypothyroidism Diagnosis

Answer 6

Vague, non specific complaints
TSH – high
T4 – low

Secondary: pituitary
Tertiary: hypothalamus

antithyroid antibodies: elevated in hashimotos and graves

Question 7

Hypothyroidism Treatment

Answer 7

Consult: myxedema, significant cardiac dx, secondary hypothyroidism

Standard of care: levothyroxine
- TAKE ON EMPTY STOMACH
- 60 min before breakfast OR
- at bedtime 3 or more hrs after even meal
- newer thinking shows consistent absorption is key - same with meals, time of day, meds
- desiccated thyroid/liothyronin not better
&raquo_space; can lead hyperthyroid effects (afib, osteo) and can increase CV risk

• many meds interact/increase or decrease absorption
  CYP inducers (pheny, carbamez) decrease levo level
  TCA increase levo level
• avoid with antacids ca iron
• 4 hour gap ^

Question 8

Hypothyroidism Treatment Goals

Answer 8

1. resolution of symptoms (including signs, biological and physiologic markers)
2. achieve normal TSH 0.5-3.5
3. avoid overtreatment esp (iatrogenic thyrotoxicosis) esp in elder

Question 9

Brand Switch Levothyroxine

Answer 9

okay to switch, mcg to mcg

Question 10

Hypothyroid Treatment - 2 methods

Answer 10

Healthy Adults: Levothyroxine(T4) 1.6mcg/kg/day

1. Full replacement for young/middle aged
   - when TSH > 10
   - based on total body weight
2. partial replacement with gradual increase
   - when TSH < 10
   - 25-50mcg/day

Known CVD
- 12.5-25mcg/day

Elderly with no CVD
- 25-50mcg/day

Dose Adj: 12.5-25mcg q 4-6weeks

1kg = 2.2lbs

Question 11

Hypothyroidism Follow Up

Answer 11

TSH/T4 q 4-6 weeks
then when Stable TSH/T4 : Check q 6*12mo
-undetectable TSH: overtreatment
-TSH > 20: undertreatment/non adherence