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?
- Insulin
- What increased blood sugar?
-
-glucagon
-cortisol
-epi
-growth hormone - Insulin
-
-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
-CORRELATES WITH INSULIN LEVELS (generally) - 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
-orthotoludidine - What may interfere with glucose reading?
-
-increased HCT can increase glucose
-ascorbic acid or lipemia -
Fasting Glucose:
Adult
Neonate
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
**ALL VALUES MUST BE IN RANGE TO BE CONSIDERED NORMAL
*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?
- <6%
- 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:
-
-diabetes
-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)
-hypothyroidism
-starvation - 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:
-
-chylomicrons
-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
-
<5
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?
-
-lifestyle
-familial hyperlipidemia
-pregnancy
-uncontrolled diabetes - Causes of decreased cholesterol?
-
-severe liver disease
-malnutrition
-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:
-
-malabsoprtion
-hyperthyroidism - 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:
-
-Albumin
-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 - Albumin
-
-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:
-
-dehydration
-gammopathies
-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) - Immunoglobins
- -proteins that act as antibodies in the immune system