Lecture5 Endocrine and Cardiovascular Laboratory Values

Question 1

What are factors that can affect blood glucose levels?

Answer 1

diet (carb component), exercise, endocrine hormones (insulin, glucagon), cell membrane receptors (GLUT4)

Question 2

What are the different types of blood glucose lab values?

Answer 2

A. Random Blood Glucose: sample taken during a non-fasting state, should be <11.1 mmol/L, Ref range: 3.3-11.0, Crit: <2.6 or >24.9

B. Fasting Blood Glucose: no food consumed in previous 8 hours, should be <7.0 mmol/L, Ref range: 3.3-6.0

C. Oral Glucose Tolerance Test: sample taken 2 hours after a 75 mg glucose load, should be <11.1 mmol/L, Ref range: <7.8

D. Hemoglobin A1c: glycated protein, indicates avg blood glucose levels over previous 2-3 months, should be <7.0 mmol/L, Ref range: 4.3%-5.9%

Question 3

What hormones are looked at when measuring thyroid fx?

Answer 3

A. Thyrotropin releasing hormone (TRH) - regulates release of TSH from anterior pit

B. thyroid stimulating hormone (TSH) - regulates release of T3 and 4 from thyroid, present in systemic circulation, used to monitor thyroid fx, Normal: 0.2-4.0 mU/L, Ref range: 0.2-6.5 mU/L

C. tetraiodothyronine (T4) (more abundant), 99.9% protein bound ⇒ measure free T4 ⇒ Ref: 10-25 pmol/L

and triiodothyronine (T3) is more potent, 99.6% protein bound ⇒ measure free T3, Ref: 3.0-6.5 pmol/L

often used to assess hyperthyroidism

Question 4

What are drugs that can interfere with thyroid fx lab tests?

Answer 4

lithium, amiodarone, propanolol, corticosteroids, oral contraceptives, phenytoin, carbamazepine

Question 5

What are the different adrenal fx lab values?

Answer 5

adrenocorticotropic hormone (ACTH): Ref: Calgary (06:30-10:30) - 2.0-11.5 pmol/L, Edmonton (08:00-10:00) - 1.6-3.9 pmol/L

B. Cortisol: Ref (blood): Morning - 120-620 nmol/L, afternoon - 85-460 nmol/L, Ref (urine): 24 hour urine collection <230 nmol

Question 6

What drugs and conditions can affect adrenal fx lab values?

Answer 6

corticosteroids, estrogen, spironolactone

pregnancy, severe injury, physical or emotional stress

Question 7

S&S of Adrenal Insufficiency

Answer 7

weakness, lethargy, fatigue, anorexia, weight loss, hypoglycemia

Question 8

S&S of Adrenal Excess

Answer 8

increased body weight, redistribution of body fat (centripetal obesity), HTN, hirsutism

Question 9

What is a lipid panel?

Answer 9

reports blood levels for directly measured values: total cholesterol (sum of all cholesterols, HDL, LDL, VLDL), HDL, triglycerides, apoprotein B (ApoB)

and calculated - non-HDL-C [TC-HDL], LDL (NIH equation)

Question 10

What are the flagging limits for lipid panels regarding the lipids?

Answer 10

Total Cholesterol: >5.20 mmol/L

HDL Cholesterol: Males - <1.00 mmol/L, Females: <1.30 mmol/L

Non-HDL-C: >4.20 mmol/L

LDL: >3.50 mmol/L

Triglycerides: >1.70 mmol/L

Apoprotein B (ApoB): >1.05 g/L

Question 11

What are the different lab values for cardiac injury?

Answer 11

Cardiac proteins: A. Troponin I, high sensitivity (HS-TnI) - <18 ng/L (upper ref limit)

B. Troponin T, high sensitivity (HS-TnT) - <14 ng/L (upper ref limit)

Cardiac enzyme: C. creatine kinase MB

Question 12

What is creatine kinase and what causes it to increase?

Answer 12

its an enzyme present in other tissues identified by fractional unit - BB = brain, MB = cardiac tissue, MM = cardiac and skeletal muscle

causes of its increase are skeletal muscle - vigorous exercise, trauma, rhabdomyolysis

cardiac muscle - myocarditis, acute MI

Meds: statins, fibrates, ethanol (binge drinking), IM injections

Question 13

What steps are involved in the coagulation process?

Answer 13

Platelet activation: platelets swell and create pseudopods, clump together and form a plug

Fibrin formation: clotting factors released by platelets and other cells create fibrin matrix that stabilizes the plug and produces an insoluble clot

Question 14

Platelets, where are they made, lifespan, ref range, and conditions associated?

Answer 14

formed in extravascular spaces of bone marrow

Lifespan: 8-12 days

removed from circulation by spleen, liver, bone marrow

ref range: 140-400 x 10^9/L

Conditions: thrombocytopenia (low count) - AEs, liver disease, thrombocytopenia purpura

thrombocytosis (high count) - bleeding, iron deficiency, some cancers, problems with bone marrow, splenectomy, trauma

other conditions are Vit-K deficiencies - malnutrition, fat malabsorption (decrease absorption of Vit K), drug interactions with warfarin

Question 15

What is prothrombin time (PT)?

Answer 15

measures how long it takes (in seconds) for blood to clot in presence of sufficient conc of Ca2+ and tissue thromboplastin - coagulation is activated through extrinsic pathway

this (aka Factor II) is one of several Vit-K dependent clotting factors made by liver - indirectly this will help assess liver fx, was mainly used to monitor warfarin therapy

wide variation in lab reagents and instruments used to measure this - ref range varies from lab to lab, most labs only report now the INR

Question 16

International Normalized Ratio (INR)

Answer 16

is = PT(patient) / PT(control)

control PT: is standardized for potency of the thromboplastin reagent developed by WHO

Ref range: 2-3

Question 17

Partial Thromboplastin Time (PTT)

Answer 17

used to monitor effects of unfractionated heparin

measures how long it takes (in seconds) for blood to clot - coagulation activated through intrinsic pathway (excludes factors VII (tissue factor) and XIII (fibrin stabilizing factor)

an activated this includes the addition of an activator to accelerate the clotting time

Ref: 60-70 seconds, activated form is 30-40 seconds