2. Decreased values are associated with

 a. Increased risk of coronary heart disease when

HDL—Cholesterol is less than 45 mg/dL in men

and less men 55 mg/dL in women.

 b. Inheritance and chronic physical inactivity (25–35

mg/dL). Long level distance runners have higher

levels of HDL.

3. Levels can be either high or low in primary biliary

cirrhosis, chronic hepatitis, or alcoholism.

Interfering Factors

1. Decreased HDL is associated with smokers.

2. Increased HDL is associated with moderate intake of

alcohol.

3. Iodine contrast substances interfere with test results.

4. Recent weight gains or losses can interfere with the

test results.

Patient Preparation

1. Overnight fasting is required. Water is permitted.

2. If possible, all medication should be withheld for 24

to 48 hours before testing—confer with attending

physician regarding this.

3. Ask patient if there has been any drastic change in

weight in last few weeks before testing.

Patient Aftercare

Person with decreased HDL can be counseled to take

measures to increase levels by losing weight, cutting down

on calories consumption, eating less red meat, and taking

lecithin supplements. Moderate alcohol consumption is

believed by some to be a factor in increased HDL.

Cholesterol: LDL and VLDL

Very low density lipoproteins (VLDL) and low-density

lipoproteins (LDL).

Normal Values

VLDL cholesterol: 25–50%

LDL cholesterol: 62–185 mg/dL.

VLDL is a major carrier of triglyceride (60-70%

triglyceride, 10–15% cholesterol). Degradation of VLDL

leads to a major source of LDL. Circulating fatty acids are

vitalized by the liver to form triglycerides that are packaged

with apoprotein and cholesterol and exported into the

blood as very low density lipoproteins.

LDLs are the cholesterol rich remnants of the lipid

transport vehicle, VLDL. Since, LDL has a longer half-life

(3–4 days) than its precursor, VLDL, LDL is more prevalent

in the blood. It is finally catabolized in the liver and

possibly in nonhepatic cells as well.

LDL-Cholesterol Fully Enzymatic, Colorimetric Test

(Courtesy: Randox)

Principle

Low-density lipoproteins (LDL) are precipitated by heparin

at their isoelectric point (pH 5.04). After centrifugation the

high-density lipoproteins (HDL) and the very low-density

lipoproteins (VLDL) remain in the supernatant. These can

then be determined by enzymatic methods.

LDL-cholesterol = Total cholesterol–cholesterol in the

supernatent.

Sample

Serum

Reagents

Contents Initial Concentration of Solution

1. Precipitation Reagent

 Heparin 50,000 IU/L

 Sodium citrate 0.064 mol/L, pH 5.04.

Preparation of Reagents

1. Precipitation reagent

 Ready for use

 Stable up to expiry date when stored at + 2 to + 8°C.

2. Reagent solution for cholesterol determination.

Procedure

Wavelength 500 nm Hg 546

Cuvette 1 cm light path

488 Concise Book of Medical Laboratory Technology: Methods and Interpretations Temperature + 20 to + 25°C, 37°C

Pipette into centrifuge tube

Serum 100 µL

Precipitation reagent (1) 1000 µL

Mix well, have to stand for 10 minutes at + 15 to

+ 25°C and centrifuge for 15 minutes at approx. 4000

rpm. Determine the cholesterol concentration of the

supernatant within 1 hour after centrifugation.

Pipette into test tubes:

Reagent blank Standard Sample

Distilled water 50 µL

Standard 50 µL

Supernatant 50 µL

Reagent (2) 1000 µL 1000 µL 1000 µL

(Cholesterol reagent)

Mix well, incubate for 10 minutes at + 20 to + 25°C

or for 5 min at 37°C and measure the absorbance of the

sample (Asample) against the reagent blank.

Calculation

Using a standard

Concentration of cholesterol in the supernatant:

 Asample __________ × concentration of std.

 Astandard

Calculation of the LDL-cholesterol

LDL-cholesterol = Total cholesterol—cholesterol in the

supernatant.

Using a Factor

Cholesterol concentration of the supernatant

= Asample × F

Factor (F) is given in table below:

mmol/L mg/dL

Hg 546 49.63 1920

500 nm 32.70 1265

Calculation the LDL-Cholesterol

LDL–cholesterol = total cholesterol— cholesterol in the

supernatant

Clinical Interpretation

mg/dL mmol/L

No treatment required < 150 3.9

Suspect range 150–190 3.9–4.9

Treatment required > 190 > 4.9

Note

Low-density lipoproteins and the very rare atherogenic Lp(a)

are precipitated qualitatively. There is a slight coprecipitation

of the VLDL but as the cholesterol content of these is low, the

LDL cholesterol values are not increased significantly and

the estimation of cardiovascular risk is not affected.

Test Significance

This test is specifically done to determine the risk of coronary

heart disease. The low-density lipoproteins are closely

correlated with an increased incidence of atherosclerosis

and coronary heart disease. One on the other hand, a

decreased incidence of coronary heart disease is seen in

persons with high levels of HDL.

 

HDL CHOLESTEROL

PEG/CHOD-PAP Method

(Courtesy: Tulip Group of Companies)

For the determination of HDL cholesterol in serum or

plasma (for in vitro diagnostic use only).

Summary

Lipoproteins are the proteins which mainly transport fats in

the bloodstream. They can be grouped into chylomicrons,

very low density lipoproteins (VLDL), low density

lipoproteins (LDL) and high density lipoproteins (HDL).

Chylomicrons and VLDL transport mainly triglycerides,

though VLDLs also transport some amount of cholesterol.

LDL carries cholesterol to the peripheral tissues where it

can be deposited and increase the risk of arteriosclerotic

heart and peripherial vascular disease. Hence, high levels

of LDL are atherogenic. HDL transports cholesterol from

the peripherial tissues to the liver for excretion, hence,

HDL has a protective effect. The measurement of total

and HDL cholesterol and triglycerides provide valuable

information for the risk assessment of coronary heart

diseases.

Principle

When the serum is reacted with the polyethylene glycol

contained in the precipitating reagent, all the VLDL and

LDL are precipitated. The HDL remains in the supernatant

and is then assayed as a sample for cholesterol using the

cholesterol (CHOD/PAP) reagent.

Normal Reference Values

Prognostically

favorable

Standard

risk level

Risk

indicator

HDL cholesterol

(mg/dL)

Males

Females

> 55

> 65

35–55 < 35

45–65 < 45

LDL cholesterol

(mg/dL)

Males

Females

< 150 150–190 > 190

Total cholesterol

HDL cholesterol

Males

Females

> 3.8

> 3.1

3.8–5.9

3.1–4.6

< 5.9

< 4.6

It is recommended that each laboratory establish its

own normal range representing its patient population.

Contents 75 mL

L1 : Enzyme reagent 1 60 mL

L2 : Enzyme reagent 2 15 mL

L3 : Pricipitating reagent 2.5 mL

S : HDL cholesterol standard (25 mg/dL) 5 mL

Storage/stability

Contents are stable at 2–8°C till the expiry mentioned on

the labels.

Reagent Preparation

Reagents are ready to use.

Working reagent: Pour the contents of 1 bottle of L2 (Enzyme

reagent 2) into 1 bottle of L1 (Enzyme reagent 1). This working

reagent is stable for at least 8 weeks when stored at 2–8°C.

Upon storage the working reagent may develop a slight pink

color however this does not affect the performance of the

reagent.

Alternatively for flexibility as much of working reagent

may be made as and when desired by mixing together

4 parts of L1 (Enzyme reagent 1) and 1 part of L2 (Enzyme

reagent 2). Alternatively 0.8 mL of L1 and 0.2 mL of L2 may

also be used instead of 1 mL of the working reagent directly

during the assay.

Sample Material

Serum, EDTA plasma. Cholesterol and HDL cholesterol

are reported to be stable in serum for 7 days when stored

at 2–8°C. The sample should preferably be of 12 to 14 hours

fasting.

Procedure

Wavelength/filter : 505 nm (Hg 546 nm)/green

Temperature : 37°C/RT

Light path : 1 cm

Precipitation of VLDL and LDL

Pipette into a clean dry test tube :

Precipitating reagent (L3) 0.1 mL

Sample 0.1 mL

Mix well and incubate at RT for 5 minutes. Centrifuge at

2500-3000 rpm to obtain a clear supernatant.

Cholesterol Assay

Pipette into clean dry test tubes labeled as blank (B),

standard (S), and test (T):

Clinical Chemistry 485

Addition

Sequence

B

(mL)

S

(mL)

T

(mL)

Working reagent 1.0 1.0 1.0

Distilled water 0.05 - -

HDL standard (S) - 0.05 -

Supernatant * - - 0.05

Mix well and incubate at 37°C for 5 minutes or at RT

(25°C) for 15 minutes. Measure the absorbance of the

standard (Abs. S), and test sample (Abs. T) against the

blank, within 60 minutes.

* If only total cholesterol is to be determined use only

0.01 mL of DW/cholesterol Std/sample directly in the

cholesterol assay.

Calculations

 Abs. T

HDL cholesterol in mg/dL = _______ × 25 × 2 Abs. S

(Where 2 is the dilution factor due to the deproteinization step)

Calculation of LDL Cholesterol (mg/dL)

(Friedewald’s Formula)

 Triglycerides

= Total cholesterol _ (_____________ (

_ HDL cholesterol 5

Friedewald’s formula is reliable provided that:

1. No chylomicrons are present, i.e. it is a fasting sample.

2. Triglyceride values are below 400 mg/dL.

3. Type III hyperlipoproteinemia is absent.

Linearity

This procedure is linear upto 150 mg/dL of HDL cholesterol.

If values exceed this limit, dilute the serum with normal

saline (NaCL 0.9%) and repeat the assay. Calculate the

value using the proper dilution factor.

Note

The supernatant should be clear. If it is hazy or cloudy,

the sample should be diluted 1 + 1 with normal saline

(NaCL 0.9%) and the precipitation step should be repeated

(Results × 2)

Anticoagulants such as fluoride, oxalates and hemolyzed

serums should not be used.

System Parameters

Reaction : End Point Interval : -

Wavelength : 505 nm Sample

volume

: 0.05 mL

Zero setting : Reagent blank Reagent

volume

: 1.00 mL

Incubation

temperature

: 37°C/RT Standard : 25 mg/dL × 2

Incubated

time

: 5 min/15 min Factor : -

Delay time : - Reaction

slope

: Increasing

Read time : - Linearity : 150 mg/dL

No. of read : - Units : mg/dL

Risk Factor

Coronary heart disease (CHD) risk factor can be calculated

using total lipid profile, as suggested by Castelli, et al. The

risk factor gives a most accurate and definite assessment of

heart disease risk.

The factors are calculated by the ratio of total cholesterol

to HDL—cholesterol and by the ratio of LDL—cholesterol

(Low density lipoproteins—cholesterol) to HDL—

cholesterol.

Risk Ratio: Total/ Ratio: LDL/

HDL__Cholesterol HDL__Cholesterol

Men Women Men Women

½ Average 3.43 3.27 1.00 1.47

Average 4.97 4.44 3.55 3.22

2 × Average 9.55 7.05 6.25 5.03

3 × Average 23.99 11.04 7.99 6.14

HDL Cholesterol ppt Set (PEG Precipitation Method)

(Courtesy: Tulip Group of Companies)

For the determination of HDL cholesterol in serum or

plasma (for in vitro diagnostic use only).

Summary

Lipoproteins are the proteins which mainly transport fats in

the bloodstream. They can be grouped into chylomicrons,

very low density lipoproteins VLDL, low density lipoproteins

(LDL) and high density lipoproteins (HDL). Chylomicrons

and VLDL transport mainly triglycerides, though VLDLs

also transport some amount of cholesterol. LDL carries

cholesterol to the peripheral tissues where it can be deposited

and increase the risk of arteriosclerotic heart and peripheral

vascular disease. Hence, high levels of LDL are atherogenic.

HDL transports cholesterol from the peripheral tissues to

the liver for excretion, hence HDL has a protective effect. The

Contd...

Contd...

486 Concise Book of Medical Laboratory Technology: Methods and Interpretations measurement of total and HDL cholesterol and triglycerides

provide valuable information for the risk assessment of

coronary heart diseases.

Principle

When the serum is reacted with the polyethylene glycol

contained in the precipitating reagent, all the VLDL and

LDL are precipitated. The HDL remains in the supernatant

and is then assayed as a sample for cholesterol using the

cholesterol (CHOD/PAP) reagent.

Normal Reference Values

Prognostically standard Risk

favourable risk level indicator

HDL cholesterol

(mg/dL)

Males

Females

> 55

> 65

35–55

45–65

< 35

< 45

LDL cholesterol Males < 150

Females

150–190 > 190

Total cholesterol

HDL cholesterol

Males > 3.8 3.8–5.9 < 5.9

Females > 3.1 3.1–4.6 < 4.6

It is recommended that each laboratory establish its

own normal range representing its patient population.

Contents 10 mL

L1: Precipitating reagent 10 mL

S: HDL cholesterol standard (25 mg/dL) 5 mL

Storage/Stability

Contents are stable at 2–8°C till the expiry mentioned on

the labels.

Reagent Preparation

Reagents are ready to use.

After the precipitation step cholesterol reagent is

required additionally for conducting the cholesterol assay.

Sample Material

Serum, EDTA plasma. HDL cholesterol is reported to

be stable in serum for 7 days when stored at 2–8°C. The

sample should preferably be of 12 to 14 hours fasting.

Procedure

Precipitation of VLDL and LDL:

Pipette into a clean dry test tube

Precipitating reagent (L1) 0.1 mL

Sample 0.1 mL

Mix well and incubate at RT for 5 minutes. Centrifuge at

2500–3000 rpm to obtain a clear supernatant.

Procedure for the Cholesterol Assay

Wavelength/filter : 505 nm (Hg 546 nm)/green

Temperature : 37°C/RT

Light path : 1 cm

Pipette into clean dry test tubes labeled as blank (B),

standard (S), and test (T):

Addition B S T

Sequence (mL) (mL) (mL)

Working reagent 1.0 1.0 1.0

Distilled water 0.05 - -

HDL standard (S) - 0.05 -

Supernatant - - 0.05

Mix well and incubate at 37°C for 5 mm. or at RT (25°C)

for 15 minutes. Measure the absorbance of the standard

(Abs S), and test sample (Abs T) against the blank, within

60 minutes.

Calculations

 Abs T

HDL cholesterol in mg/dL = _______ × 25 × 2 Abs S

(Where 2 is the dilution factor due to the deproteinization

step)

Calculation of LDL cholesterol (mg/dL):

(Friedewald’s formula)

 Triglycerides = (Total cholesterol) _ _______________

5 _ (HDL cholesterol)

Freidewald’s formula is reliable provided that:

1. No chylomicrons are present, i.e. it is a fasting sample.

2. Triglyceride values are below 400 mg/dL.

3. Type III hyperlipoproteinemia is absent.

Linearity

This procedure is linear upto 150 mg/dL of HDL cholesterol. If values exceed this limit, dilute the serum with

normal saline (NaCL 0.9%) and repeat the assay. Calculate

the value using the proper dilution factor.

Note

The supernatant should be clear. If it is hazy or cloudy,

the sample should be diluted 1 + 1 with normal saline

(NaCL 0.9%) and the precipitation step should be repeated

(results × 2).

Anticoagulants such as fluoride, oxalates and hemolyzed

serums should not be used.

Clinical Chemistry 487

System Parameters

Reaction : End point Interval :

Wavelength : 505 nm Sample

volume

: 0.05 mL

Zero setting :  Reagent

blank

Reagent

volume

: 1.00 mL

Incubation

temperature

: 37°C / RT Standard : 25 mg/dL × 2

Incubated

time

: 5 min/15 min Factor

Delay time : — React slope : Increasing

Read time : — Linearity : 150 mg/dL

No. of read : — Units : mg/dL

Clinical Relevance

1. Increased values are associated with a chronic liver

disorder.

 

Clinical Chemistry 481

Causes of Monoclonal Gammopathies

¾ Multiple myeloma

¾ Waldenstrom’s macroglobulinemia

¾ Benign idiopathic monoclonal gammopathy

¾ Heavy chain diseases

¾ Collagen disorders, autoimmune diseases

¾ Certain lymphomas

¾ Cirrhosis liver

¾ Neoplasms of colon, prostate, breast, female genital

tract, stomach and lungs

¾ Myeloproliferative disorders-CML, polycythemia,

myelofibrosis, erythrimic myelosis, erythroleukemia,

other acute leukemias

¾ Aberrations in lipid metabolism

¾ Diabetes mellitus.

Interfering Factors

1. Low levels of albumin occur normally in all trimester’s

of pregnancy.

2. Bromosulfalein may cause a false elevation. Therefore,

a serum protein test should not be done within 48 hours

following a BSP test.

3. See appendix for complete listing of drugs that

interfere with total protein levels.

SERUM CHOLESTEROL

Cholesterol (CHOD/PAP Method)

(Courtesy: Tulip Group of Companies)

For the determination of cholesterol in serum or plasma

(for in vitro diagnostic use only).

Summary

Cholesterol is the main lipid found in blood, bile and brain

tissues. It is the main lipid associated with arteriosclerotic

vascular diseases. It is required for the formation of

steroids and cellular membranes. The liver metabolizes

the cholesterol and it is transported in the blood

stream by lipoproteins. Increased levels are found in

hypercholesterolemia, hyperlipidemia, hypothyroidism,

uncontrolled diabetes, nephrotic syndrome, and cirrhosis.

Decreased levels are found in malabsorption, malnutrition, hyperthyroidism, anemias and liver diseases.

Principle

Cholesterol esterase hydrolyzes esterified cholesterols to

free cholesterol. The free cholesterol is oxidised to form

hydrogen peroxide which further reacts with phenol and

4-aminoantipyrine by the catalytic action of peroxidase to

form a red colored quinoneimine dye complex. Intensity

of the color formed is directly proportional to the amount

of cholesterol present in the sample.

 Cholesterol esterase

Cholesterol esters + H2O Cholesterol + Fatty acids

 Cholesterol oxidase

Cholesterol + O2 Cholestenone + H2O2

 Peroxidase

H2O2 + 4 Aminoantipyrine + Phenol Red

quinoneimine

dye + H2O

Normal Reference Values

Serum/plasma (Suspicious) : 220 mg/dL and above

(Elevated) : 260 mg/dL and above

It is recommended that each laboratory establish its

own normal range representing its patient population.

Contents 2 × 75 mL 2 × 150 mL

L1: Enzyme reagent 1 2 × 60 mL 2 × 120 mL

L2: Enzyme reagent 2 2 ×15 mL 2 × 30 mL

S: Cholesterol standard (200 mg/dL) 5 mL 5 mL

Storage/Stability

Contents are stable at 2–8°C till the expiry mentioned on

the labels.

Reagent Preparation

Reagents are ready to use.

Working reagent: Pour the contents of 1 bottle of L2

(Enzyme reagent 2) into 1 bottle of L1 (Enzyme reagent

1). This working reagent is stable for at least 8 weeks when

stored at 2–8°C. Upon storage the working reagent may

develop a slight pink color however, this does not affect the

performance of the reagent. Alternatively for flexibility as

much of working reagent may be made as and when desired

by mixing together 4 parts of L1 (Enzyme reagent 1) and

1 part of L2 (Enzyme reagent 2). Alternatively 0.8 mL of L1

and 0.2 mL of L2 may also be used instead of 1 mL of the

working reagent directly during the assay.

Sample Material

Serum, EDTA plasma. Cholesterol is reported to be stable

in the sample for 7 days when stored at 2–8°C. The sample

should preferably be of 12 to 14 hours fasting.

482 Concise Book of Medical Laboratory Technology: Methods and Interpretations Procedure

Wavelength/filter : 505 nm (Hg 546 nm)/green

Temperature : 37°C/RT

Light path : 1 cm

Pipette into clean dry test tubes labeled as blank (B),

standard (S), and test (T):

Addition

Sequence

B

(mL)

S

(mL)

T

(mL)

Working reagent 1.0 1.0 1.0

Distilled water 0.01 - -

Cholesterol standard (S) - 0.01

Sample - - 0.01

Mix well and incubate at 37°C for 5 minutes or at RT (25°C)

for 15 minutes. Measure the absorbance of the standard

(Abs S), and test sample (Abs T) against the blank, within

60 minutes.

Calculations

 Abs T

Cholesterol in mg/dL = ________ × 200 Abs S

Linearity

This procedure is linear upto 750 mg/dL. If the value

exceeds this limit, dilute the serum with normal saline

(NaCL 0.9%) and repeat the assay. Calculate the value

using the proper dilution factor.

Note

Anticoagulants such as fluorides and oxalates result in

false low values. The test is not influenced by Hb values

upto 20 mg/dL and bilirubin upto 10 mg/dL.

System Parameters

Reaction : End point Interval : ...

Wavelength : 505 nm Sample

volume

: 0.01 mL

Zero setting :  Reagent blank Reagent

volume

: 1.00 mL

Incubation

temperature

: 37°C / RT Standard : 200 mg/dL

Incubated

time

: 5 min/15 min Factor :

Delay time : — React slope : Increasing

Read time : — Linearity : 750 mg/dL

No. of read : — Units : mg/dL

Normal values

Male Female

SI units SI units

Age mg/L mmol/L mg/dL mmol/L

Total cholesterol

Adult

20–24 124–218 3.21–5.64 122–216 3.16–5.59

25–29 133–244 3.44–6.32 128–222 3.32–5.75

30–34 138–254 3.57–6.58 130–230 3.37–5.96

35–39 146–270 3.78–6.99 140–242 3.63–6.27

40–44 151–268 3.91–6.94 147–252 3.81–6.53

45–49 158–276 4.09–7.15 152–265 3.94–6.86

50–54 158–277 4.09–7.17 162–285 4.20–7.38

55–59 156–276 4.04–7.15 172–300 4.45–7.77

60–64 159–276 4.12–7.15 172–297 4.45–7.69

65–69 158–274 4.09–7.10 171–303 4.43–7.85

> 70 144–265 3.73–6.86 173–280 4.48–7.25

Child

Cord blood 44–103 1.14–2.66 50–108 1.29–2.79

< 4 114–203 2.95–5.25 112–200 2.90–5.18

5–9 121–203 3.13–5.25 126–205 3.26–5.30

10–14 119–202 3.08–5.23 124–201 3.21–5.20

15–19 113–197 2.93–5.10 119–200 3.08–5.18

High-density lipoprotein cholesterol (HDL)

Adult

20–24 30–63 0.78–1.63 33–79 0.85–2.04

25–29 31–63 0.80–1.63 37–83 0.96–2.15

30–34 28–63 0.72–1.63 36–77 0.93–1.99

35–39 29–62 0.75–1.60 34–82 0.88–2.12

40–44 27–67 0.70–1.73 34–88 0.88–2.28

45–49 30–64 0.78–1.66 34–87 0.88–2.25

50–54 28–63 0.72–1.63 37–92 0.96–2.38

55–59 28–71 0.72–1.84 37–91 0.96–2.35

60–64 30–74 0.78–1.91 38–92 0.98–2.38

65–69 30–75 0.78–1.94 35–96 0.91–2.48

> 70 31–75 0.80–1.94 33–92 0.85–2.38

Child

Cord blood 6–53 0.16–1.37 13–56 0.34–1.45

5–9 38–75 0.98–1.94 36–73 0.93–1.89

10–14 37–74 0.96–1.91 37–70 0.96–1.81

15–19 30–63 0.78–1.63 35–74 0.91–1.91

Contd...

Clinical Chemistry 483

Low-Density lipoprotein Cholesterol (LDL)

Adult

20–24 66–147 1.71–3.81 57–159 1.48–4.12

25–29 70–165 1.81–4.27 71–164 1.84–4.25

30–34 78–185 2.02–4.79 70–156 1.81–4.04

35–39 81–189 2.10–4.90 75–172 1.94–4.45

40–44 87–186 2.25–4.92 74–174 1.92–4.51

45–49 97–202 2.51–5.23 79–186 2.05–4.82

50–54 89–197 2.31–5.10 88–201 2.28–5.21

55–59 88–203 2.28–5.26 89–210 2.31–5.44

60–64 83–210 2.15–5.44 100–224 2.59–5.80

65–69 98–210 2.54–5.44 92–221 2.38–5.72

> 70 88–186 2.28–4.82 96–206 2.49–5.34

Child

Cord

blood 20–56 0.52–1.45 21–58 0.54–1.50

5–9 63–129 1.63–3.34 68–140 1.76–3.63

10–14 64–133 1.66–3.44 68–136 1.76–3.52

15–19 62–130 1.61–3.37 59–137 1.53–3.55

SI Units

Cholesterol

esters

60–75% of total or 0.60–0.75

< 210 mg/dL < 5.43 mmol/L

Free

cholesterol

< 50 mg/dL < 1.29 mmol/L

LDL:HDL

ratio

< 3 < 3

Clinical Relevance

1. Increased levels of cholesterol

 a. Levels above 250 mg/dL are considered elevated

and call for a triglyceride test.

 b. Conditions related to elevated cholesterol

 1. Cardiovascular disease and atherosclerosis

 2. Type II, familial hypercholesterolemia

 3. Obstructive jaundice (also an increase in

bilirubin)

 4. Hypothyroidism (decreased in hyperthyroidism)

 5. Nephrosis

 6. Xanthomatosis

 7. Uncontrolled diabetes

 8. Nephrotic syndrome

 9. Obesity.

 c. Free versus esterified cholesterol.

 There is a markedly abnormal ratio of free to esterified

cholesterol in disease of the liver biliary tract,

infectious disease, and extreme cholesterolemia.

2. Decreased levels of cholesterol

 a. Conditions where cholesterol is not absorbed

from the gastrointestinal tract

 1. Malabsorption

 2. Liver disease

 3. Hyperthyroidism

 4. Anemia

 5. Sepsis

 6. Stress

 7. Drug therapy such as antibiotics.

 b. Other disorders related to decreased cholesterol

levels

 1. Pernicious anemia

 2. Hemolytic jaundice

 3. Hyperthyroidism

 4. Severe infections

 5. Terminal stages of debilitating diseases such as

cancer

 6. Hypolipoproteinemias.

 c. Esterol fraction decreases in liver diseases,

liver cell injury, malabsorption syndrome, and

malnutrition.

3. Increased levels of cholesterol esters are associated

with familial deficiency of Lecithin—cholesterol

acyltransferase (LCAT).

4. Decreased levels of cholesterol are associated with

liver disease. This is because persons with liver

diseases may have impaired formation of LCAT with

a resulting deficiency of the enzyme.

5. Cholesterol ester storage disease causes accumulation

of cholesterol esters in the tissues, but it has no effect

on the percentage of esterified cholesterol in the

blood.

6. The higher the cholesterol phospholipid ratio, the

greater the possible risk of developing atherosclerosis.

Interfering Factors

1. Cholesterol is normally slightly elevated in pregnancy.

2. Estrogen decreases plasma cholesterol and oophorectomy increases it.

3. Many drugs may cause a change in the blood cholesterol

Patient Preparation

1. Advise patient about fasting for a night for 12 hours

before the test.

2. Water is permitted.

3. Before fasting, the patient should be on a normal diet

for 7 days before testing.

Contd...

484 Concise Book of Medical Laboratory Technology: Methods and Interpretations 4. No alcohol should be consumed 24 hours before

testing.

5. Lipid lowering drugs such as estrogen, oral contraceptives,

and salicylates should be withheld.