Heme/Endocrine Flashcards
What lab parameters are you looking out for iron deficiency anemia?
NORMAL - Hemoglobin: women >12g/dL, pregnant>11 g/dL, men >13g/dL - Reticulocyte Count: Women: 0.8-2 RBC Men: 0.8-2.3 RBC ABNORMAL - TIBC elevated >400mcg/dL - Ferritin <120ng/L (goal >500ng/L)
What would microcytic or macrocytic mean corpuscular volume (MCV) indicate?
Microcytic <79fL: thalssemia low ferritin iron deficiency Macrocytic >96fL: folate deficiency Vit B12 deficiency
What labs are you monitoring for folate deficiency?
- goal for serum folate level>4ng/mL - elevated homocystein level means low folic acid
What labs are you monitoring for Vit D levels? When would you have f/u labs?
25 (OH)D goal 30-32ng/dL deficient <20ng/dL severe deficiency < 12 ng/dL toxicity > 150 ng/dL - 3 months of therapy
What labs are you monitoring for Vit B-12 deficiency?
Serum B-12 assay, normal 150-200 pg/mL ABNORMAL: high methylmalonic acid (MMA)
What would you give for iron deficiency anemia? What are some common SE of this med?
Ferrous Sulfate 325mg (65mg elemental iron) 3x/day - n/v/d/constipation - may stain teeth
What are monitoring parameters for Ferrous Sulfate?
Ferritin goal >500 ng/L & H/H in range - up to 6-8 weeks for Hb to improve, even as long as 6 months - retuculocytosis in 7- 10 days
When is Ferrous Sulfate contraindicated?
hemochromatosis hemolytic anemia
What medications affect absorption of Ferrous Sulfate?
- Chelation: levodopa, penicillin, fluorquinolones. - Decreased absorption: Calcium (antacids, milk), aluminum and magnesium, cimetidine, methyldopa & tetracyclines.
When is Vit B-12 supplement indicated?
- pernicious anemia - Crohn’s - Gastric bypass
What are some causes of Vit B-12 deficiency?
Poor diet Lack of intrinsic factor ETOH Wt loss sx H pylori Crohns dx Fish tapeworm
What are monitoring parameters for B-12 replacement?
Serum B-12 assay (N 150-200pg/mL) Less than 200 is deficient 7-10 days for reticulocytosis Hct rise in 2 weeks & normal in 2mo
When is ORAL B-12 not recommended?
Oral vitamin B12 is not recommended for pernicious anemia, due to insufficient absorption due to lack of intrinsic factor.
Why is early diagnosis of B-12 deficiency important?
-early dx is important bc neuro deficits can occur: i.e. unsteady gait, paresthesia, slow thinking (first in extremities then moves up) if left untreated can be irreversible
Who should receive folic acid replacement indefinitely?
Patients w/hemolytic anemia, malabsorption or chronic malnutrition should receive oral folic acid indefinitely.
Why is folic acid important prenatal & during pregnancy?
prevent birth defects of brain and spinal cord
What medications would you need to increase your folic acid intake with?
methotrexate dilantin
What is the MOA of unfractionated heparin?
Bind to antithrombin III, inactivate Factor 2A and 10A, clotting cascade pathway Inactivate thrombin and prevent conversion of fibrinogen to fibrin
When would is Heparin indicated?
Undergo surgery or hemodialysis
Tx of thrombosis
Prophylaxis of VTE
Given inpatient
What are side effects of Heparin?
Bleeding
Heparin induced thrombocytopenia
What are monitoring parameters for Heparin? What is the antidote?
Bleeding
Heparin induced thrombocytopenia
aPTT
Subsequent tx of warfarin
Antidote: IV protamine sulfate
What meds are low molecular weight heparin? What’s the MOA?
enoxaparin
dalterparin
tinzaparin
Anticoagulant effect via binding to antithrombin which irreversibly inactivates clotting factor Xa
When would is low molecular weight heparin indicate?
Treatment & secondary prevention of VTE
Treatment of ACS
Prevent clot formation
What are monitoring parameters and antidote of low molecular weight heparin?
May need Subsequent tx of warfarin
Can monitor by anti-Za activity but shown to be linearly related so no need to monitor
Antidote: IV protamine sulfate
What are patient education for LMWH?
Ensure someone reliably & accurately administer sq injection
on or arrange HH
Monitor for heparin-induced thrombocytopenia
What is the MOA of warfarin/Coumadin?
Vitamin K Antagonist
Inhibit activation of clotting factors that depend on Vit K (factors 2,7,9,10)
Completely inhibits VKORC1 that activates Vt K in body, depletes reserves & reduce synthesis of clotting factors
Who is warfarin best indicated for?
Prevention of valve thrombosis w mechanical heart valves, prevention of VTE in ortho sx, & tx & secondary prevention of VTE
Preferred for those w renal disease
Best for those who can’t take novel anticoag:
ESRD
Mechanical valves
What are monitoring parameters for warfarin?
Check INR, long onset of effect
Goal: INR 2-3
(2.5 -3.5 for prosthetic heart valves or hypercoagulable conditions)
Labs:
Daily for 2 consecutive days, Dose change q3 days then 2x/weeks for few weeks then monthly
(usually pair w UFH or LMWH for acute DVT/PE)
Start at 5mg/day or lower based on co-morbidities: elevated liver enzymes, >75yo, thyroid status
What population is warfarin contraindicated or cautioned with? What is the antidote?
Pregnancy X
Caution w fall risk, dementia, HTN
Antidote Vitamin K
What drugs affect warfarin?
These drugs decrease effect:
(risk for thrombus)
OCPs
Carbamazepine
Barbiturates
Antifungals
These drugs increase effect:
(risk for bleeding)
SSRI’s
Fluoroquinolones, Bactrim (reduce by 50% then check lab in 3d)
NSAIDS
What drugs are Direct Thrombin Inhibitor Anticoagulants? What is their MOA?
Prevent fibrinogen to fibrin by thrombin
dabigatran etexilate
(Pradaxa)
Only oral
When are Direct Thrombin Inhibitor Oral Anticoagulants indicated?
CVA & thromboembolism prevention
Prophylaxis, reduce risk, & tx DVT & PE
Do any of the Direct Thrombin Inhibitor Oral Anticoagulants have an antidote? What labs are you checking before starting medication?
Pradaxa only med in class w antidote (Praxbind)
However, to reverse bleeding for those without antidote only can d/c med, RBC transfusion, & explore source of bleeding
Before initiation check:
PT, PTT, platelet, Cr <15
What are some drug/drug interactions with Direct Thrombin Inhibitor Oral Anticoagulants
P-glycoprotein inhibitors
(risk for bleeding)
ketoconazole
verapamil
P-glycoprotein inducers
(risk for clots)
phenytoin
rifampin
What meds are Factor Xa Inhibitors? What’s the MOA?
Bind directly to factor Xa [-xaban]
rivaroxaban (Xarelto)
apixaban
(Eliquis)
edoxaban
(Savaysa)
What are some drug/drug interactions with Factor Xa inhibitors?
Contraindicated w dual inhibitors of CYP-3A4 & P-glycoprotein
(risk for bleeding)
Antifungals
ritonavir
Contraindicated w dual inducers of CYP-3A4 & P-glycoprotein
(risk for clot)
phenytoin
rifampin
What are potential causes of hypothyroidism?
Failure of thyroid gland itself (Primary hypothyroidism)
Pituitary or hypothalamic disease (secondary or tertiary hypothyroidism)
Drugs: Amiodarone, Lithium
Radiation
Iodine deficiency
Chronic autoimmune thyroiditis (Hashimoto’s)
Primary hypothyroidism
Elevated TSH
Low T4
Secondary hypothyroidism
Pituitary dysfunction
Low T4
Low TSH
Tertiary hypothyroidism
Due to hypothalamus
Low T4
Low TSH
What are TSH goals?
TSH goal is 0.5-4.0mIU/mL. Some resources say high normal of 2.5 (p811)
When do you check labs for TSH?
In reading:
<65yo dose levothyroxine 1.6mcg/kg (round to nearest 25mcg)
> 65yo OR cardiac disease, start at 12.5-25mcg per day
Check TSH every 3 months (textbook) until normal then once a year, check T4 only if they still have symptoms
Check labs for children more often
What is the MOA of levothyroxine?
Synthetic form of T4 (inactive form)
prodrug
What are monitoring parameters for levothyroxine?
More monitoring: phenytoin (Dilantin), chemo & carbamazepine (Tegretol)
Amiodarone increases TSH
What is time frame response for levothyroxine?
6-8 weeks to reach steady state, lab of serum TSH (also T4)
(focus on sx)
Check every 6 months, at least once per year
What are contraindications for levothyroxine?
Uncorrected renal cortical insufficiency
Adrenal insufficiency
Thyroid toxicosis
What are special considerations for special populations?
Pediatrics:
Require 4-10mcg/kg/d bc rapid metabolism
Need higher dose
Geriatric
Start at lower dose
Symptoms:
Ataxia
Paresthesia
Carpal tunnel
depression
At risk for bone density issues (may need Dexa scan)
Pregnancy:
Check every trimester
More T4 bound in circulation will need to increase dosing
What is patient education for levothyroxine?
take on empty stomach 30-60min before meal, DO NOT take within several hours before or after
cholestyramine (Questran)
sucralfate (Carafate)
aluminum-containing antacids
calcium carbonate
What are some dose adjustments with levothyroxine?
Oral contraceptives or estrogen replacement therapy: need to increase T4 dose
niacin & androgen: need to decrease T4 dose
Salicylates & high dose Lasix: decrease affinity of T4 & T3 to TBG (thyroid-binding globulin) displace hormones & increase free T4 & T3
Monitor anticoag studies more with Coumadin (increase bleeding time)
Limit non-Rx decongestants
What are potential causes of hyperthyroidism?
Graves disease, autoimmune disease (most common)
Toxic nodular goiter (Plummer disease)
Thyrotoxicosis factitia- intentionally take high T4 doses (p.814)
Toxic adenoma
When are follow up lab checks for hyperthyroidism?
Evaluate every 1-3 months after start of therapy (T4 level)
Euthyroid within 6-12 weeks of beginning antithyroid
Can decrease dose & reevaluate in 3-4mo
What is 1st line for treating hyperthyroidism?
Radioactive Iodine
What are monitoring parameters and contraindications for radioactive iodine?
After treatment hypothyroidism, check TSH & T4
Pregnancy, lactation
Cannot get pregnant for 6mo post tx
What is the drug of choice for treatment of hyperthyroidism? What’s the MOA?
methimazole
tapazole
Block production of thyroid hormone T3 & T4 in thyroid gland
Blocks oxidation of iodine (prevent T4 to T3)
What are side effects for methimazole and PTU?
Urticaria
Arthralgia
Transient granulocytopenia
Hepatic abnormalities
GI upset
Fever
Rash, itching
agranulocytosis
What is the effect of Iodine on methimazole?
Iodine intake caution can enhance med
Can you take methimazole in pregnancy?
1st trimester of pregnancy PTU okay, methimazole okay 2-3 trimester
What are some drug/drug interactions with methimazole?
Enhances effects of digoxin, clozapine, theophylline
What are some drug/drug interactions w PTU?
Enhances effects of warfarin, digoxin
What is the MOA of PTU?
Interferes
Peripheral conversion of T4 to T3
Inhibit iodine & peroxidase that help to form T4 & T3
What is the time response and monitoring parameters of PTU?
Routine CBC monitoring 1st 3 months
(agranulocytosis)
Report sx of sore throat & fever immediately!
Takes several weeks to work
Iodine intake caution can enhance med
What are considerations for geriatrics and women w hyperthyroidism?
Encourage women of childbearing age to consider definitive treatment (radioiodine or surgery) before conception
PTU in 1st Trimester then Methimazole in 2nd or 3rd Trimester
May need higher dosing
Geriatric:
Do not overtreat due to natural rise in TSH
What is the MOA of Beta blockers? Which ones are used for hyperthyroidism?
propranolol
atenolol
Decrease sx of adrenergic stimulation
Block sympathetic NS activation
What are the indications of use of beta blockers in hyperthyroidism?
Adjunct agents, treat symptoms
Suppress tachycardia
Given during thyroid storm
Prevent hyperthyroid-induced AFib or control ventricular rate
What are signs and symptoms of hypothyroidism?
What are signs and symptoms of hyperthyroidism?
