Glossary of Clinical Lab: Carbs, Proteins, Lipids

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Carbohydrates are...
-complex sugars
-metablized into basic sugars
Blood glucose may change d/t...
-inc or dec metabolism of carbs into sugar
-inc or dec rate of consumption of glucose by cells
-hormones help to regulate glucose movement into and out of the cell
What decreased blood sugar?
What increased blood sugar?
-growth hormone
-produced in pancreas in islets of langerhans (beta cells)
-controls cells ability to take glucose from the blood stream (increases cells uptake of glucose)
What factor is most important in regulating insulin secretion?
circulating concentration of blood glucose
Diabetes Mellitus
-disruption of insulin relgulation
-deficient beta cell insulin production or release (pancreatic factor)
-insulin receptor dysfcn (extra-pancreatic factor)
Testing/Monitoring Diabetes
-measuring insulin is ideal but difficult and costly
-C-peptide predicts insulin levels
What is c-peptide?
-insulin precursor
-protein connecting alpha chain of pro-insulin
-released into bloodstream when insulin is produced
Can use c-peptide instead of insulin for..
-diabetics with anti-insulin antibodies
-pt who secretly admin insulin to themselves
-diabetic taking insulin
-pts with insulinoma (excess insulin)
What is more accurate than whole blood glucose for monitoring glucose?
serum glucose
Tube of choice for glucose monitoring
serum separator tube (completely separates cells and serum)
If whole blood glucose is your only option for monitoring glucose, what tube should you use?
-Grey top tube (NaFl) because it blocks glucose metabolsim
-normally whole blood glucose drops 10 mg/dl for each hour it sits
What do most labs used for monitoring glucose?
automated glucose oxidase methodology
CLIA approved procedures for monitoring glucose include...
-glucose oxidase
What may interfere with glucose reading?
-increased HCT can increase glucose
-ascorbic acid or lipemia
Fasting Glucose:
Gestational Diabetes
Non gestational Diabetes
Adult: 70-115 mg/dl
Neonate: 30-40 mg/dl
Gestational Diabetes: >105 mg/dl
Non-gestational Diabetes: >140 mg/dl
Glucose Tolerance Tests:
-3 hr procedure used to rule out DM in border line cases
-prep includes 150 gm carb diet for 3 days, followed by 12 hour fast
Glucose Tolerance Test: Expecected reactions
Fasting: 70-100 mg/dl
Peak (30 min -1 hour): 120-170 mg/dl
1 Hour: 120-170 mg/dl
2 Hours: 70-120
3 hours: 70-120
*If you extend it for 5 hours, it can detect hypoglcemia (values will drop below 70 and stay down for a long time)
how do test results differ with diabetics?
-after the peak, there is a slow decrease
Under normal circumstances, glucose attached to ....
Beta chain of hemoglobin A
glucose + hemoglobin A produces...
hemoglobin A1C
What is the link between glycosylation of hemoglobin and blood glucose levels?
Glucosylation will increase with sustained levels of blood glucose

(increase in blood glucose levels leads to increases glycosylation)
Hb A1C values indicate glucose levels over what amount of time?
over the past 3 months

Because of RBCs lifespan (110-120 days)
High glycosylated hemoglobin levels indicates...
poor control in a diabetic
What is the Normal non-diabetic glycosylated Hb level?
How is glycosylated Hb test used?
-to monitor diabetic therapy
-differentiate short term hyperglycemia from a diabetic condition
-eliminate ficticous report by pt
Causes of hyperglycemia:
-states of stress (MI, CVA, trauma, general anesthesia)
-acute panreatitis
-drugs (corticosteroids, some dieretics, beta blockers)
-IV fluids with dextrose
Causes of hypoglycemia:
-excess inslun
-sulfonylurea (drugs that cause pancreas to produce insulin)
-insulinoma (excess insulin)
Plasma lipoproteins carries most of the ..... and ...... in the blood
carries most of the cholesterol and esterified lipids in the blood
4 major lipoprotein classes:
-very low density lipoproteins (VLDL)
-low density lipoproteins (LDL)
-high density lipoproteins (HDL)
Major fucntion of the lipoproteins is...
transport of trigylceride and cholesterol from sites of origin (intestine and liver) to sites of energy storage and utilization
Normal Triglycerides
Male: 40-160
Female: 35-135
Normal Total Cholesteral
<200 mg/dl
Normal HDL
>40 mg/dl
Normal LDL
<100 mg/dl
Normal Chol:HDL ratio

10 = double the risk
20 = triple the risk
Which lipid values change with fasting state? Which do not?
Triglycerides change with a fasting state

Total cholesterol does not
Cholesterol is the main lipid associated with....?
arteriosclerotic vascular disease
Is cholesteral a good indicator of CAD?
by, itself, cholesterol is NOT an accurate predictor of CAD (it fluctuates daily)
What is a better measure of CAD?
Total cholesteral:HDL ratio
What is cholesterol used for?
required for production of sex hormones, steroids, etc.
What percentages of cholesteral are bound to LDL and HDL?
75% to LDL

25% to HDL
Causes of increased cholesterol?
-familial hyperlipidemia
-uncontrolled diabetes
Causes of decreased cholesterol?
-severe liver disease
-MI (levels falls 24-48 hours, reach low point at 7-10 days at ~30-40% lower than normal)
Where are tricglycerides produced,transported, etc.?
-Produced in the liver and tranported by LDL
-Incorporated into the chylomicrons (protein shell)
-gives blood a milky appearance if too high
Triglycerides are hydrolyzed by .... into ....
hydrolyzed by pancreatic lipase into FFA and monoglycerides
Triglycerides can be measured as an assessment of...
Coronary risk
Causes of increased triglycerides:
-glycogen storage disease
-familial hyperlipidemia
-chornic renal disease
Causes of decreased triglcyerides:
Where and how is LDL produced?
Produced in the liver by combingin Tg and cholestereol with apoproteins
LDL consists of...
35% protein
50% cholesterol
10% Tg
What does LDL do?
-carries Tg to peripheral tissue to be used by cells
-contributes to deposition of cholesterol in the artery walls
LDL values:
<100 desirable (<70 if hx of MI)

100-160 borderline

>160 high risk
HDL consists of..
50% protein
20% cholesterol
trace Tg
What does HDL do?
-transports cholesterol from tissue back to liver
-offers some protection from atherosclerosis
HDL values:
Male 35-65 mg/dl (<35 is CAD risk)

Female 35-80 mg/dl (<40 is CAD risk)
What are apolipoproteins?
-polyproteins that make up the protein component of lipoproteins
-involved in the binding of lipoproteins to receptors on the cell surface (facilitates lipid uptake by cells)
What is the major polypeptide component of HDL? of LDL?
HDL: Apolipoprotein A

LDL: Apolipoprotein B
Indication for apolipoproteins labs?
evaluate the risk of atherogenic heart disease or peripheral vascular disease
Factors affecting lipid panel results:
-pt not on usual diet for past 2 weeks
-medications (OCPs, estrogens, BP meds)
-thyroid, hepatic, or kidney dz
-prolonged use of touniquet during blood draw (inc level)
-pregnancy (inc level)
Two main types of proteins:
-Globulin (lipoprotein, glycoprotein, immunoglobulins)
What can be used to separate albumin and globulin?
-protein electrophoresis can be used to separate albumin and globulin and establishes levels of various components that are specific for certain disease states
Electrophoresis is used to ..
-detect gammopathies
-assess severe liver dz
-assess nutritional status
-most common protein (2/3 of total)
-smaller and light than globulins
-produced in liver
What does Albumin do?
-maintains serum osmotic pressure
-transports various substances (carrier protein) such as calcium, magnesium, bilirubin, coumadin, etc.
-source of endogenous amino acids
Albumin assays
-assayed by chemical method that react with nitrogen atoms or with a dye that binds to albumin and produces a color change
-ultra-centrifugation has been used to study some groups of globulins
Total serum protein =
albumin + globulins
Normal Total Serum Protein
Adults: 6-8 g/dl
Causes of hyperproteinemia:
-liver dz
-collage disorders (SLE,RA)
Causes of hypoproteinemia:
-increased protein loss (nephrotic syndrome, burns, etc)
-increased catabolism (inflammation, malignancy)
-decreased synthesis (liver dz, decreased AA intake)
-proteins that act as antibodies in the immune system

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