Metabolic and Cardiac Diagnostic Labs Flashcards
Diabetes is a disorder of the (…) cells
pancreatic beta cells
What is the normal function of pancreatic beta cells?
secrete insulin in response to glucose intake causing increased cellular glucose uptake
- Which type of diabetes is an acute onset of immune0mediated insulin deficiency related to destruction of pancreatic beta cells?
- When does the onset of this diabetes usually occur?
- type 1 diabetes
- pediatric onset
What does type 1 diabetes require from onset (treatment)?
requires exogenous insulin administration
- What type of diabetes occurs when insulin uptake in cells is impaired and there is a slower destruction of beta cells in the pancreas?
- When does the onset of this diabetes occur?
- type 2 diabetes
- gradual onset - adulthood
How is type 2 diabetes usually treated?
oral medications initially
Which diabetes occurs in pregnancy?
gestational diabetes
What test is used to diagnose diabetes when a fasting or random glucose reading is elevated?
hemoglobin A1c test
What is the hemoglobin A1c test used to monitor?
- control of diabetes
- risk of diabetes-related complications
What makes up 98% of hemoglobin?
hemoglobin A
What makes up 7% of hemoglobin A?
hemoglobin A1
What makes up 80% of hemoglobin A1?
hemoglobin A1c
What is a the component of hemoglobin A1 that combines most easily and strongly with glucose (glycosylated and hemoglobin)?
hemoglobin A1c
What % of A1c does the average person typically have?
5.6
- A percentage of hemoglobin is (…) which is generally slow and (…)
- Because glycosylation is hard to reverse, we can use the (…) percentage to determine the patient’s glucose level over a (…) month period
- glycosylated (sugar attached)
- irreversible
- HgbA1c
- 3 month period
How do you calculate mean plasma glucose?
(35.6 x HgbA1c) - 77.3
What are the hemoglobin A1c values in these individuals?
- non-diabetic adult or child
- pre-diabetes
- diagnosis of diabetes
- goal for most established diabetics
- poor control
- 4.5-5.7%
- 5.7-6.4%
- > 6.5% of total hemoglobin
- <7% (“lucky 7”)
- > 8% of total hemoglobin
By the time someone has been diagnosed with type 2 diabetes, how much of their pancreatic beta cells have they lost?
50%
Every 1% reduction in HgbA1c results in a reduced risk in what conditions?
- diabetes related deaths
- myocardial infarctions
- microvascular complications
- amputations or deaths
What test is used to ascertain functioning of the patient’s pancreas and ability to produce insulin and can help distinguish between type 1 and type 2 diabetes?
C-peptide test
What would the values of the C-peptide test be in type 1 diabetes compared to a person with type 2 diabets?
the C-peptide would be lower in type 1 diabetes due to the pancreas no longer producing insulin adequately compared to an individual with type 2 diabetes where their pancreas still has some insulin function
- What is the precursor of insulin?
- What does this consist of?
- What separates in the beta cells of the Islet of Langerhans within the pancreas?
- proinsulin
- consists of alpha and beta chains with C-peptide as the connector of chains
- the chains of proinsulin
- What is the C-peptide value for someone with type 1 diabetes?
- What is the C-peptide value for someone with type 2 diabtes?
- low c-peptide = pancreas failing to produce insulin
- normal c-peptide = pancreas produces some insulin, but cells have reduced uptake of it for use
What are the top 3 causes of pancreatitis, an inflammatory process that occurs in the pancreas?
- long-term alcohol use or binge drinking (most common)
- gallstones
- high triglyceride levels (>1000) (least common)
- Why does long-term alcohol use/binge drinking cause pancreatitis?
- Why do gallstones cause pancreatitis?
- Why do high triglyceride levels cause pancreatitis?
- catabolism of alcohol causes release of harmful pancreatic enzymes and damage to pancreatic ducts
- results in obstruction of enzymes that would normally be released by GI tract
- high lipid values can cause damage to capillaries and structures of the pancreas
If a patient presents with extreme pain in the epigastric region, nausea, and vomiting, what may they have?
pancreatitis
What test is ordered in the evaluation of abdominal pain and is specifically used to detect pancreas?
amylase level
A pancreatitis patient presents with what symptoms?
- upper abdominal pain that may radiate to the back
- pain is often worse after eating
- fever
- nausea
- vomiting
What enzyme is secreted from the acinar cells of the pancreas which travels through the pancreatic duct into the duodenum?
amylase
- What is amylase involved in?
- When damage occurs to the acinar cells, (…) pours out into the lymphatic system, free peritoneum, and circulatory system
- Damage of the acinar cells can occur (…) cells or from obstruction of the (…)
- catabolism of carbohydrates
- amylase pours out
- within cells (OR)
- obstruction of the biliary tract
- Amylase is (…) cleared by the kidneys, so levels can return to normal within (…) hours of onset of illness or trauma
- Persistent or severe disease can cause persistently (…) levels of amylase
- rapidly cleared
- 12 hours
- elevated levels
What causes an increase in amylase levels?
- acute/chronic pancreatitis
- pancreatic cancer
- bile duct obstruction by gallstone
- cholecystitis
- renal failure (diseased clearance)
- ectopic pregnancy
- mumps
Where else can amylase be found?
- fallopian tubes
- salivary glands
- gallbladder
What is a better level to measure for pancreatitis and is used to diagnose pancreatitis in the evaluation of abdominal pain?
lipase level
- What is lipase secreted by and into?
- What is it involved in?
- When there is damage to pancreatic acinar cells, (…) is released into the circulations and levels become elevated
- What is lipase excreted via?
- secreted by the pancreas into the duodenum
- involved in the catabolism of triglycerides and fatty acids
- lipase
- excreted via the kidneys
- Lipase can be dramatically elevated in pancreatic disease, up to (…) normal level
- What is more specific for pancreatic injury?
- Why is lipase better than amylase?
- Currently, lipase is used to diagnose what?
- 5-10x normal level
- lipase
- lipase rises a little later and sticks around a little longer (5-7 days)
- solely to diagnose acute pancreatitis (without amylase)
- Uric acid is the end byproduct of what?
- What are the building blocks of DNA?
- What do sources of purines include?
- Uric acid that results from purine catabolism is primarily excreted by (…)
- purine nucleotide catabolism
- purines and pyrimidines
- diet, degradation of nucleotides or endogenous synthesis of new purines
- kidneys but also by the intestinal tract
What causes elevated uric acid?
- high animal protein diets (high purine levels)
- alcohol use/abuse (metabolism of alcohol increases uric acid production)
- diuretic use (medications can increase uric acid reabsorption/decrease uric acid secretion in gout
- cancer (increased purine metabolism)
- renal failure (poor excretion of uric acid by kidneys)
Uric acid levels are frequently elevated in (…); this condition is known as (…)
- gout
- hyperuricemia
At levels > 6.8 mg/dl, uric acid can be deposited into (…) in the form of monosodium urate crystals
- joint tissues
What is the name for gout in the first metatarsal and is the most frequent location of gout and is very painful?
podagra
What occurs when the heart is not able to pump blood adequately and perfuse all tissues sufficiently and is complex and multifactorial?
heart failure
What can cause heart failure?
- hypertension
- coronary artery disease
- valvular heart disease
- diabetes mellitus
- congenital heart disease
What generally function to inhibit the reabsorption of sodium in the renal tubule so that sodium excretion in urine is increased?
natriuretic peptides
- What are the three major natriuretic peptides?
- Which one is the most important
- ANP, BNP, C-type natriuretic peptide (CNP)
- BNP
- ANP is synthesized in (…)
- BNP was initially identified in the (…) but primarily released from the (…) of the heart
- CNP is found in the (…) and (…)
- atrial cardiomyocytes
- identified by the brain; released from the ventricles
- found in the nervous system and endothelium
- What are released when atria and ventricles stretch (heart failure)?
- This can also occur when what happens?
- ANP and BNP
- when myocardium is “stressed” as in an MI
When ANP and BNP are released, what do they cause?
vasorelaxation and increase the amount of sodium and water excreted → diuresis and natriuresis
During heart failure and MI, both (1) and (2) are released, trying to reduce the amount of stretch and stress on the heart
- ANP
- BNP
What symptoms will you have if your heart is not pumping adequately?
- SOB
- swollen legs
- What is the indication for BNP?
- BNP has a strong correlation to (…)
- BNP can be used in the diagnosis of what with an accuracy of what?
- What do higher BNP levels mean?
- to aid in the diagnosis of heart failure
- left ventricular pressures
- diagnosis of heart failure with an accuracy of 83%
- increases severity of CHF/dysfunction
- Increased BNP = probably (…)
- What BNP value “rules in” heart failure
- CHF
- > 500
Where is BNP levels frequently used?
the ED
When will a patient have increased BNP?
- congestive heart failure
- myocardial infarction
- hypertension
- cor pulmonale (right-sided heart failure)
- What is the prehormone of BNP?
- What does this prehormone get cleaved into?
- ProBNP
- BNP and N-terminal fragment BNP
When muscles are very active, they need a large amount of ATP for energy to sustain that high powered action. In order to generate enough ATP, (…) found in the mitochondria and cytoplasm of skeletal muscles is metabolized to phosphocreatine and ATP is generated in the process. Without this process, ATP would be depleted within (…) seconds
- creatine
- 10 seconds
- What is creatine kinase also known as?
- Where is creatine kinase mostly found?
- What three different isoenzymes does creatine kinase exist as?
- creatine kinase
- cardiac, skeletal muscle, and brain (high energy tissues)
- CK-MM, CK-BB, CK-MB
- Which creatine kinase isoenzyme is predominantly found in skeletal mm and is nearly all of the body’s CK in this form (94-99%)?
- Which CK isoenzyme is predominantly found in the brain?
- Which CK isoenzyme is predominantly found in the heart and is specific for cardiac cells, and can also exist in small amounts in skeletal muscle?
- CK-MM
- CK-BB
- CK-MB
What is elevated in disorders/injury to muscle or neurologic disease?
creatine kinase
- Elevation of total CK (CPK) usually represents what?
- What factors can influence total CK?
- People with larger muscle mass can be expected to have (…) levels of CK
- injury to skeletal mm
- age, gender, race, physical activity
- higher levels of CK
What can lead to increased total CK?
- strenuous exercise
- recent surgery
- rhabdomyolysis (statis use/medications for cholesterol; excessive exercise w/ poor prep)
- myositis
- recent convulsions
- trauma or crush injuries
- neuromuscular disorders
What tests specifically for injury to the myocardium and rises 3-6 hours after myocardial infarction, is not elevated in all patients until 12 hours, and returns to baseline in 36-48 hours?
CK-MB
Because CK-MB can also be released from skeletal muscle, what can happen?
may be falsely elevated in patient with underlying muscle disorder or injury
Previously, (…) was the marker used to detect myocardial infarction or damage, but no longer preferred
CK-MB
Why is CK-MB not preferred when diagnosing myocardial infarction?
- lack specificity
- lack sensitivity
- late increase in disease process
- high CK-MB levels can indicate extensive myocardial damage has already occurred
What can lead to increased CK-MB?
- acute MI
- cardiac ischemia
- myocarditis
- ventricular arrhythmias
Damage to the myocardial cells causes (…) to “spill” from the cells into circulation
CK-MB
What are proteins that control the interaction of actin and myosin in skeletal and cardiac muscle?
troponins
- What do troponins interact with?
- When troponin is bound by calcium, it allows what?
- interact with calcium ions and tropomyosin during muscle contraction
- allows exposure of the myosin binding sites on actin
- What are the three subtypes of troponin?
- Which one contains the calcium binding site?
- Which one inhibits the interaction of actin and myosin?
- Which one binds troponin and tropomyosin?
- I, T, C
- troponin C
- troponin I
- troponin T
What is the cardiac specific subtype of:
- troponin I
- troponin T
- troponin C
- cTnI
- cTnT
- none
Which troponin subtypes are used to diagnose MI?
- troponin I
- troponin T
- Troponin is more (…) and (…) than CK-MB for the diagnosis of myocardial injury
- Cardiac troponin rises (…) and stays around (…)
- Troponin levels rise (…) hours after onset of myocardial injury and remain elevated for (…) days after
- Often several sets of troponin levels are ordered (…) and (…) hours later
- specific and sensitive
- faster; longer
- rise 2-3 hours; elevated for 7-14 days after
- 6-12 and 24 hours later
What is the indication for troponin levels/tests
diagnostic test in the evaluation of chest pain to determine if there is a cardiac cause to chest pain and to evaluate pts with suspect acute coronary syndrome
Which troponin is used more commonly for diagnostic purposes? Why?
cardiac troponin I used more commonly than T because renal failure more frequently increases cardiac troponin T
What is the preferred test to diagnose a pt with acute coronary syndrome or MI?
troponin
What causes elevated troponin?
- MI
- unstable angina
- congestive heart failure
- myocarditis
- severe pulmonary embolism
- CPR, cardioversion or pacemaker firings
What is a close relative of hemoglobin, but only occur in skeletal or cardiac mm?
myoglobin
What does myoglobin serve as?
serves as short-term oxygen storage in muscle tissue
Myoglobin is only released into serum when there is a (…)
skeletal or cardiac muscle injury
Myoglobin is known to increase how long after cardiac injury?
3 hours (early marker)
What is more sensitive than CK-MB but not as specific for MI due to other conditions causing elevation?
myoglobin
What results in elevated myoglobin?
- MI
- myositis
- skeletal muscle injury
- seizures
- muscular dystrophy
- recent cocaine use
- trauma or inflammation
- What can occur when a person has one or more risk factors for hypercoagulability?
- A person develops a blood clot in a vein (usually in their lower extremity) that can travel to the (…)
- How might this present?
- DVT and pulmonary embolism
- pulmonary arteries
- swollen leg, discoloration
What is left behind when a clot is dissolved?
fibrin degradation products (FDPs)
- What is formed during lysis of cross-linked fibrin through the action of plasmin?
- What is this used for?
- D-dimer
- used to identify when a patient has intravascular clotting
What is the indication for D-dimer levels?
primarily used to diagnose a pt with a DVT or PE
D-dimer is highly (…) but not (…) enough
highly sensitive but not specific enough
What should be combined with other tests to diagnose DVT or PE?
D-dimer
What causes elevated D-dimer levels?
- disseminated intravascular coagulation (DIC)
- sickle cell anemia
- surgery
- pregnancy
- elderly pts
What can D-dimer be used to monitor?
efficacy and duration of thrombolytic therapy
What is the indication for the lipid panel?
evaluate for dyslipidemia
What is dyslipidemia a risk for?
coronary artery disease
Lipid panels are helpful to determine which patients benefit from (…)
cholesterol medication
What is the leading cause of mortality worldwide?
coronary heart disease
Cholesterol is integral to many body functions including production of what?
- steroids
- sex hormones
- bile acids
- cellular membranes
What is cholesterol metabolized in and what is it carried on to circulation?
metabolized in the liver, carried on lipoproteins to circulation
- Low-density lipoproteins carry (…) of cholesterol
- High-density lipoproteins carry (…) of cholesterol
- 75%
- 25%
What tests are generally included in a lipid panel?
- total cholesterol
- triglyceride
- HDL (high-density lipoprotein: GOOD)
- LDL (low-density lipoprotein: BAD)
- What sticks to the artery walls leading to plaque formation?
- What carries LDL away from the artery walls?
- LDL
- HDL
- What is the goal value of total cholesterol?
- Screening with total cholesterol alone can be (…) due to variation between drawings
- 0-199
- unreliable
- What is the goal value of triglycerides?
- What are triglycerides synthesized from?
- What type of diet increases this level?
- What would the values be in diabetes?
- What about malnutrition?
- normal: 0-150, borderline: 150-199, high: 200-499, very high: 500+
- carbohydrates in diet
- high carb diet
- diabetes: high level
- malnutrition: low level
- What is the goal value of HDL?
- What is the function of HDL?
- What does it protect against?
- men: acceptable >40, women: acceptable >50, desired for both: >60
- to transport cholesterol from tissues of the body and the vascular endothelium returning it to the liver
- protects against coronary heart disease when high (increased risk of CHD when low)
- What is the goal value of LDL?
- LDL particles are rich in what?
- Where is this deposited into?
- What is LDL strongly associated with?
- 70-100 (ideal for those at risk of heart disease); 100-130 (near ideal)
- rich in cholesterol
- walls of the arteries
- increased risk of atherosclerosis and CHD
What factors increase HDL?
- genetics
- exercise
- moderate alcohol use
- healthier eating choices
- estrogen administration
What factors decrease HDL?
- tobacco use
- genetics
- metabolic syndrome
What factors increase LDL?
- genetics
- high saturated fat in diet
- excessive alcohol consumption
- chronic liver disease
- hypothyroidism (body does not remove LDL efficiently)
What factors decrease LDL?
- genetics
- low fat diet
- exercise
- hyperthyroidism
- LCL is most commonly calculated by the (…) formula
- This is only a valid formular if (…)
- What is this formula?
- Friedewald formula
- only if triglyceride level <400 mg/dL
- LDL = total chol - (HDL + 1/5 Tg)
- LDL particles can vary in size and density; gel electrophoresis can be used to identify which types and the quantity. What patterns do they divide into?
- Which ones are good and bad?
- Pattern A: large particle size
- Pattern B: small, dense particle size (higher ability to enter walls of blood vessels and increased risk of CHD)
- Pattern I: intermediate particle size
- Small and dense: bad
- Big and fluffy: good
Why does small LDL particle promote atherosclerosis and thrombosis
- increased half-life in circulation due to decreased receptor binding
- increased oxidative stresses
- increased penetrance of arterial walls
