Endocrine Flashcards
Typical T4 replacement dose
1.6 mcg/kg
Clinical Presentation of Hypothyroidism
Extreme fatigue, Weight gain, depression, cold intolerance, dry skin/loss of hair, constipation, irregular, heavy menses, decreased concentration, forgetfulness, bradycardia, hypothermia, hoarseness, hyperlipidemia.
Hypothyroidism Lab Values
High TSH typically 5-10 mIU/ml. Treat > 5 w/symptoms and > 10 w/o sx.
Low TT4 (normal 5-12 mcg/dl)
Low free thyroxine (FT4) (normal 0.7-1.9)
Low TT3 (normal 80-180 ng/dl)
Thyroid antibodies present in Hashimoto dz
Low RAI uptake (RAIU)
True or False…All adults 18 y/o and older should be screened for thyroid disease every 5 years.
False. The US Preventative Services Task force found insufficient evidence to recommend for or against routine screening for thyroid disease in adults.
However the American Thyroid Association does recommend everyone older than 35 y/o be screened with a TSH test every 5 years.
Levothyroxine Treatment
Typically begins with TSH greater than 5 mIU/L
stable, pure, predictable potency
serum T3 is controlled physiologically
long half life, allows daily dosing
DOC American Thyroid Association/American Association of Clinical Endocrinologists.
Take on empty stomach but some studies show bedtime versus morning with improved levels.
Titrate dose to normalization of TSH , check TSH 6-8 weeks after each dose change then every 3-6 months during first year of diagnosis, and annually thereafter.
Thyroid Dz and Pregnant Women
Pregnant Women- treat even mildly elevated TSH
Increase T4 replacement by 30% with first detection of pregnancy
Monitor TSH monthly and adjust dose accordingly
Typically wil need a 40-50% increase in T4 dose.
Some evidence that T4 is a better marker in pregnancy vs TSH.
Cardiac Disease and Thyroid Treatment
Start low 12.5 mcg and go slow in 12.5 mcg increments every 6-8 weeks.
Drug Interactions with Levothyroxine
- Decrease in T4 absorption , take T4 2 hours before or 4 hours after. Cholestyramine, Calcium, Ferrous sulfate, sucralfate, aluminium hydroxide.
- Increase in T4 metabolism. Rifampin, Phenytoin, Phenobarbital, Sertraline
- Pharmacodynamic interactions. Warfarin, Digoxin.
Hyperthyroidism Causes/Clinical Presentation
Causes: Toxic diffuse goiter (graves dz), toxic adenoma, toxic multinodular goiter, subactute thyroiditis, silent thyroiditis, iodine-induced, excessive ingestion of thyroid hormone, drugs (amiodarone), tumor
Clinical Presentation: Heat intolerance or increased sweating. Tremor Palpitations and tachycardia Nervousness and irritability Frequent bowel movements or diarrhea less frequent, shorter, lighter menses fatigue and muscle weakness thyroid enlargement weight loss despite and increased appetite Exopthalmos and/or pretibial myxedema (in graves dz only) insomnia Elderly may have minimal s/s.
Diagnosis of Hyperthyroidism
PE: Increase HR, Thyroid palpation, eye exam, dermatologic exam
Labs: Low TSH (in primary dz, could be high in secondary dz but rare) High TT4 High FT4 High TT3 Thyroid antibodies High RAIU Thyroid scan
Treatment for HTR- Radioactive iodine
Most common tx of HTR in US
C/I in pregnancy and breastfeeding
Very high risk of subsequent HoTR
Treatment for HTR- Surgery
TOC for thyroid cancer, respiratory, or swallowing difficulties
find an experienced surgeon
hypothyroidism
Treatment for HTR- Thioamides
Medications are noninvasive, minimal risk of HoTR but potential for ADRS and need long term adherence.
MOA: inhibits organification and coupling; PTU also inhibits the peripheral conversion of T4 to T3. DELAYED EFFECT (weeks)
PTU: 300-600 mg/day in 2 or 3 doses, preferred in 1st trimeter of pregnancy, lactation and thyroid storm.
Methimazole (Tapazole): 30-60 mg/day in 1 or 2 doses, longer half-life, better adherence, LESS HEPATOTOXICITY, recommended thiamide unless first trimester of pregnancy.
Often used before RAI therapy, may use for 18-24 months in Graves Dz.
ADRs Rash, fever, arthralgias, severe agranulocytosis, hepatitis.
Need to get CBC on patients before they start therapy.
Treatment for HTR- Iodides
MOA: block thyroid hormone release, inhibit organification, inhibit peripheral conversion of T4 to T3. Decrease gland size/vascularity, Rapid onset (days)
Dose:
Saturated solution of potassium iodine (38 mg/drop): 1-5 drops in juice 3/day.
Lugol’s solution (6 mg/drop): 3-5 drops in juice 3times/day
Radiographic iodinated contrast agents (1 gram daily)
Most often used in graves dz patients before surgery and in thyroid storm.
ADRs:
Allergic reactions, dose-related toxicity, metallic taste, “escape” phenomenon.
CI:
Pregnancy
Before RAI therapy
Patients with nodular goiter or adenomas.
Treatment for HTR- Beta Blockers
MOA: selective inhibitor of B1 adrenergic receptors (manages sympathetic-mediated hyperthyroid symptoms)
Inhibit T4 conversion (propranolol, nadolol)
Quick onset, (hours)
Propranolol 120-160 mg/day in 3-4 divided doses
Nadolol 80mg/day in 1 or 2 doses.
Used until more specific thyroid therapy can take effect.
ADRS
Hypotensio/Bradycardia/Fatigue.
PCOS Causes/Clinical Presentation/DX
Excess androgen production in the ovaries..leads to insulin resistance. Excess insulin also decreases hepatic synthesis of sex hormone- binding globulrin (SHBG) which normally binds free T, resulting in increased hirsutism.
CP: Chronic anovulation Hirsutism Acne Male pattern hair loss Hyperandrogenemia Insulin Resistance Acanthosis nigricans, overwieght/obese IGT, nonalcoholic steatohepatitius, abdominal obestiy.
Dx: Two of the following
Oligovulation or anovulation, elevated circulating androgens, Polycystic ovaries 12 or more 2-9mm diameter follicles in each ovary or increase ovariam volume
PCOS Treatment
Weight reduction (5-7% ) has shown improvement in androgen levels Exercise decreases insulin resistance.
Infertility: Weight loss, clomiphene, metformin
Hyperandrogenism/hirsutisim: OCs
Other:
Sprionolactone,
Elfornithine (Vaniquia) reduces hair growth
Flutamide (potent nonsteroidal antiandrogen, 250 mg daily, hepatotoxicity conerns, CI in liver dz/pregnancy)
Cyproterone: Antiandrogen often used in combo with OCs.
Topical Minoxidil for alopecia
Insulin Resistance: metformin, pioglitazone
Menstrual Irregularities/endometrial hyperplasia/OCs
See chart Table 1 on page 183 of chapter.
Prolactinoma What is it? Causes?
Pituitary tumor, that secretes excessive amounts of prolactin, most common type of pituitary tumor
Prolactin levels >30 ng/ml
Normal 15-25 ng/dml
Causes:
Levels > 200 ng/ml are usually associated with a tumor.
Modest prolactin elevation 30-100 ng/ml Pregnancy Stress Hypothyroidism Kidney failure Liver faitlure Medications "Stalk effect" any dz within or near the pituitary that interferes with delivery of dopamine from hypothalamus to prolactin secreting cells. No longer under chronic inhibition.
Drug Induced Hyperprolactenemia Causes
Dopamine antagonists: (phenothiazine, TCS, metoclopramine) SSRIs, estrogen-progesterone, Methyldopa, Verapamil, Gondadotropin-releasing hormone analogs.
Clinical Presentation of Prolactinomas
Women: Reproductive age, irregular periods, infertility, galactorrhea, reduction in sex drive, vision loss/ha, osteoporosis.
Men: 50-60’s, decreased libido, erectile dysfunction, loss of body hair. Vision loss/ha, osteoporosis.
Treatment of Prolactinomas
Transsphenoidal surgery
Radiotherapy
Drug Therapy: TOC D2 receptor agonists, stimulate postsynaptic dopamine receptors in the hypothalamus.
- Bromocritine Dose start at 1.25 mg once daily or BId and increase weekly up to 15 mg/day (preferred for fertility),
- Cabergoline 0.25 mg Bid, maximal dose of 1 mg BID. Drug interactions with 3A4 inhibitors, less nausea.
Growth Hormone Excess-Acromegaly, Causes/CP
Causes: pituitary adenoma, rarely cuased by tumors of the pancrease, lung, ovary, or breast.
CP: Enlarged hands and feet excessive sweating coarse facial features several skin tags deepened voice osteoarthritis sleep apnea increased risk of DM, colonic polyps, colon CA, CAD
Growth Hormone Excess-Acromegaly Dx
Elevated serum GH level in the fasting state and after an OGTT
Elevated IGF-1 (somatomedia C) ideal screening test
MRI with special cuts of pituitary
Growth Hormone Excess-Acromegaly- Treatment
Transsphenoidal sugary (TOC) Stereotactic radiosurgery Drug Therapy (when surgery has failed or is contraindicated) Dopamine agonists (bromocriptine, cabergoline) relative lack of efficacy
Octreotide and ocreotide LAR (Sandostatin)
Lanreotide
Pegvisomant