Thyroid/Headache/Contraception

Thyroid Hormones

influence basal metabolic rate, T3 (active) and T4 (abundant)

low T3/T4 (- feedback) = TRH from hypothalamus = TSH from anterior pituitary = T3/T4 from thyroid

small changes T3/T4 large TSH changes but small TSH no T3/T4 changes

Thyroid Disorder Classification

hyperthyroidism= increased T3/T4

hypothyroidism= decreased T3/T4

primary= thyroid issue, feedback loop still intact

secondary= outside thyroid issue, TSH wrong

euthyroidism= normal levels

overt= changes in T3/T4 seen

subclinical= TSH changes only so less symptoms

Hyperthyroidism (less prevalent)

symptoms weight loss, tachycardia, tremors, heat intolerance, ramped up= thyroid storm

mainly caused by autoimmune Graves’ disease (if getting surgery make sure euthyroid before, after start levothyroxine to bring back up)

Hyperthyroidism Treatment

radioactive iodine (RAI)

surgery

antithyroid drugs (ATD)

• methimazole (MMI)- can use in 2nd trimester, AE granulocytopenia

• propylthiouracil (PTU)- use if MMI, RAI, and surgery not appropriate or 1st trimester, boxed warning for liver injury/acute liver failure

• both present in breastmilk but MMi is preferred

beta blockers

• use to reduce tachycardia and tremors, also use if HR>90 or CV disease

Hypothyroidism (more prevalent)

symptoms weight gain, bradycardia, cold intolerance, thinning hair, dry skin, fatigue, constipation, extreme= myxedema coma

mainly caused by autoimmune Hashimoto’s

Hypothyroidism Treatment

desiccated thyroid

liothyronine

levothyroxine (do not use for weight loss)

• average maintenance 1.6mcg/kg/day, range 50-220mcg/day

• adjust 12-25mcg q3-6 wks, monitor q4-6wks

• if no coronary heart disease and >60 YO, start 25-50mcg QD, if <60 still 1.6mcg/kg/day

• if coronary heart disease, start 12.5-50mcg QD, monitor cardiac

• take same time qam empty stomach 60 mins before food or 3-4 hrs after last meal, do not take Fe/Al/Ca/Mg within 4 hrs

• can impact BG, BMD, fertility

• monitor HR, BP, cardiac symptoms, BMD, hypo/hyper, biotin interferes with labs

• switch to IV (50-75% PO dose) if NPO or myxedema coma

• NTI so do not change manufacture without documented consent from pt and prescriber and checking Orange Book

• in pregnancy increase dose by 25-50%

Migraine Pathophysiology

trigeminal nerve activation leads to nociceptor sensitization, neurogenic inflammation, and vasodilation

CGRP increased, serotonin decreased

red flags worst headache, thunderclap, etc

Abortive Migraine Treatment

1st line NSAID ± acetaminophen

2nd line triptans ± naproxen

3rd lin gepant or ditan

(progress to next line when >= 3 attacks on current therapy or insufficient response)

Triptans

dose q2h prn (q4h for naratriptan or frovatriptan)

max monthly usage =< 10 days (overuse headache)

work as serotonin agonists of 5HT1B and 5HT1D (on trigeminal nerve) to induce vasoconstriction and reduce neurogenic inflammation (not much of an SS effect)

avoid in CV disease d/t 5HT1B and 5HT1D also in coronary arteries (causes vasoconstriction)

triptan sensation (tingling, warmth, flushing) is common and okay

Gepants

less AE than triptans but higher NNT

no overuse headache issue

Preventative Migraine Therapy

triggers often conflated and overemphasized (except for menstruation), keep headache log always but don’t cut diet or environment if trigger isn’t very clear

preventative therapy indicated if >=4 headache days/mo, impacts life, or abortive treatments ineffective/too frequent

goal reduction not eradication, assess effectiveness 3-6mo (1st f/u in 1mo) at least before changing treatment unless severe AE

Preventative Therapy Migraine Options

TCAs (amitriptyline 10mg, nortriptyline)- sedation and anticholinergic, tolerance to SE can occur

SNRIs (venlafaxine 37.5mg)- insomnia, diaphoresis, GI, tolerance to SE can occur

Valproate/Divalproex- teratogenic, monitor liver enzymes, interacts with CHC, need higher doses of folic acid

Topiramate- teratogenic, interacts with CHC, weight loss

Beta blockers (propanolol, metoprolol)

CCB (flunarizine)

ACEI/ARBS (candesartan)

OnobotulinumtoxinA

Monoclonal antibodies against CGRP receptor- zumabs, well tolerated and SQ, just $$$

Migraines with Aura

CI for combined oral contraceptives, risk proportional to estrogen amount and increased by smoking