System Parameters

Reaction : UV Kinetic Interval : 60 sec

Wavelength : 340 nm Sample volume : 0.05 mL

Zero setting : Distilled water Reagent volume : 1.00 mL

Incubation

temprature

: 37°C Standard :

Incubation

time

: — Factor : 6666

Delay time : 300 sec React. slope : Increasing

Read time : 180 sec Linearity : 1000 U/L

No. of read : 4 Units : U/L

Clinical Relevance

The two enzymes CK and adenylate kinase (AK) play a

decisive role in the synthesis of ATP, the immediate energy

source of the muscle, the CNS and many proliferating

tissues. Human creatinine kinase is synthesized by a number

of different genes. The respective gene products are called

CK-M (muscle), CK-B (brain) and CK-Mi (mitochondria).

The total CK activity measurable in serum is composed of

the activities of the cytoplasmic, dimeric isoenzymes (CKMM, CK-MB, CK-BB) and their postsynthetically modified

forms, and the activities of the macrocreatinine kinase

(macro-CK).

CK Isoenzymes

Isoenzyme of total CK:

CK-BB (brain) 0–3 (found mainly in brain, also in smooth

muscle, thyroid, lungs and prostate)

CK-MB (heart) 0–6 (found mainly in myocardium, also in

tongue, diaphragm and skeletal muscle)

CK-MM (muscle) 90–97 (found mainly in the skeletal

muscle).

Approximate distribution of the CK isoenzymes in human

organs

Tissue U/g CK-MM CK-MB CK-BB CK-mito

Skeletal 800–4000 ++++ (+) (+) + muscle

Myocardium 240–800 + + + ++ (+) + +

Brain ≤ 550 - - + + + + +

Bladder ≤ 135 - ++++ +

Blood ≤ 0.2 ++++ (+)

Colon ≤ 200 (+) (+) ++++ +

Umbilical

cord blood

≤ 1.0 + + + + (+) + ?

Prostate ≤ 135 - - ++++ ?

Uterus ≤ 400 - - ++++ +

Vein wall ≤ 60 - - ++++ ?

(+ + + + :> 75%, + + + :50-75%, + + :25-50%/

 +:5-25%, (+):< 5%

at 37°C)

Normal Values (at 37°C)

Adult males 24–195 U/L, Adult females 24–170 U/L

Children: Umbilical cord 175–402 U/L, Newborns;

≤ 5 days 195–700 U/L, < 6 months 41–330 U/L, > 6 months

24–229 U/L. (Conversion of U/L into µ Kat/L: 1 µKat/L

= 60 U/L)

CK-MB: Normal value ≤ 24 U/L CK-BB:, For adults < 2

U/L.

CK-MM: Reference values for total CK activity for adults

can be used.

CK-mito: Normal value is < 2U/L.

Clinical data, ECG findings and the results of CK

determination complement each other with regard to

clinical sensitivity and specificity. In spite of determination

of CK-MB the differential diagnosis of myocardial infarction

/skeletal damage presents problems in the following

circumstances: extensive skeletal muscle damage and

concomitant small infarction, chronic skeletal muscle

disease and myocardial involvement or MI after coronary

artery bypass grafting. In these cases, determination of one

of the cardiospecific troponins is necessary.

Diagnostic Alert

As adenylate kinase (AK) interferes with CK estimation and

AK is found to a greater extent in the Indian population.

It becomes imperative to use reagents that are capable

of inhibiting AK so as not to overestimate CK. A report

generated by employing inappropriate kits can initiate

unnecessary therapy.

Total CK and CK-MB trends in acute myocardial

infarction:

Enzymology 545

Total CK CK-MB

Initial rise: 2–6 hours after onset of

damage

4–8 hours after onset of

damage

Peak levels: 18–36 hours after onset

of damage

18–24 hours after

the onset of damage

Return to

basal levels:

3–6 days after onset of

damage

3 days after onset of

damage

6% Rule

The decision criterion is an increase in the total CK activity

to > 240 U/L (37°C) within the diagnostic time window

and a simultaneous increase in CK-MB activity. A CK-MB

fraction more than 6% of the total CK activity is regarded as

diagnostic for MI. A fraction < 6% indicates skeletal muscle

damage. The clinical specificity of the 6% rule is high as

the number of false positive results caused by presence

of extracardiac CK-MB is small. However, following this

rule, smaller MIs may be missed. False positive values

can be caused by Adenylate Kinase, which occurs in large

quantities in the liver and in blood cells.

Increased Total CK

Amyotrophic lateral sclerosis, anoxia, atresia (biliary),

bowel injury, brain tumor, burns (thermal, electrical),

cancer (breast, lung, oat cell, gastrointestinal, prostatic),

carbon monoxide poisoning, cardiomyopathy (cobaltbeer), carrier state (for Duchenne’s muscular dystrophy),

cerebrovascular accident, CNS trauma, coma (hepatic),

convulsions, coughing (severe), delirium tremens,

dermatomyositis, eosinophilia-myalgia syndrome, exercise,

head injury, hemodialysis, hypokalemia (severe), hypothermia, hypothyroidism, infarction (bowel, cerebral,

myocardial, prostate), intoxication (alcohol, salicylate),

intramuscular injection (recent), labor, leptospirosis,

malignant hyperthermia, meningoencephalitis, muscle

spasms, muscular dystrophy (Duchenne’s, limb-girdle,

fascioscapulohumeral), myocarditis, myoglobinuria,

myopathy (from alcoholism), myotonic dystrophy,

myxedema, necrosis of striated muscle, organ rejection

(heart transplant), parturition, polymyositis, pregnancy,

prostatic injury, psychosis (acute with agitation), pulmonary edema, pulmonary embolism, renal failure, renal

insufficiency (chronic), Reye’s syndrome, rhabdomyolysis,

Rocky Mountain spotted fever, shock, skeletal muscle

disorders, status epiepticus, striated muscle atrophy

(acute), subarachnoid hemorrhage, surgery (bowel,

cardiac, CNS, prostate), tachycardia, thyrotoxicosis, toxic

shock syndrome (day 7), trauma (muscular), typhoid fever,

and very muscular people.

Increased CK-BB

Anoxia, atresia (biliary), cancer (breast, gastrointestinal, oat

cell, prostatic, widespread malignancies), cerebrovascular

accident (hemorrhage, infarction), hemodialysis, hypothermia, intestinal necrosis, labor, malignant hyperthermia, renal failure, shock, surgery (CNS) and uremia.

Increased CK-MB

Anoxia, burns (electrical, thermal), cancer (lung), carbon

monoxide poisoning, cardiomyopathy (cobalt-beer),

collagen vascular diseases, congestive heart failure (rare),

coronary angiography (rare), coronary insufficiency (rare),

hypothermia, hypothyroidism, malignant hyperthermias,

muscular dystrophy (Duchenne’s), myocardial infarction,

myocarditis, myoglobinuria (severe), polymyositis,

pulmonary embolism, renal insufficiency (chronic), Reye’s

syndrome, rhabdomyolysis, Rocky Mountain spotted fever,

surgery (cardiac, valve replacement), SLE, and trauma

(cardiac).

Increased CK-MM

Cardiac catheterization (with myocardial damage),

cardioversion, coronary arteriography (with myocardial

damage), hypothyroidism, intramuscular injection, muscle

trauma, myocardial infarction, psychosis (acute with

agitation), Reye’s syndrome, shock, surgery, and trauma

(skeletal muscle).

Decreased Total CK

Addison’s disease, anterior pituitary hyposecretion,

connective tissue disease, hepatic disease (alcoholic), low

muscle mass, metastatic neoplasia, and pregnancy (first

half). Drugs include steroids.

Decreased CK-BB, CK-MB, CK-MM

Clinically insignificant/not applicable.

Interfering Factors

1. Strenuous exercise (up to 3 times normal) and surgical

procedures that damage skeletal muscle may cause

increased levels.

2. High doses of salicylates may cause increased levels.

3. Athletes have a higher value because of greater muscle

mass.

4. Multiple intramuscular injections may cause increased

levels.

5. Drugs that may cause increased levels include

a. Amphotericin B

b. Ampicillin IM

546 Concise Book of Medical Laboratory Technology: Methods and Interpretations c. Carbenicillin IM

d. Chlorpromazine IM

e. Clofibrate.

Liver Disease (Serum Enzyme Patterns) Values are x

Times the Upper Normal Limits

Condition GOT GPT LDH SAP

Acute viral hepatitis 15–20 15–20 6–8 1–2

Obstructive jaundice

(intra/extrahepatic) 3–4 3–4 1–2 3–6

Cirrhosis (portal) 2–3 2–3 1–2 1–2

Secondary deposits in liver

without jaundice

1–2 1–2 1–3 1–3

GOT—glutamic-oxaloacetic transaminase

GPT—glutamic pyruvic transaminase (tends to be higher

than GOT in acute liver disorders)

LDH—lactate dehydrogenase

SAP—(Serum) alkaline phosphatase

(In obstructive jaundice in addition to others,

5-nucleotidase rises 4–6 times the upper normal limit

(UNL) and in tumor deposits in liver GGTP-GammaGlutamyl Transpeptidase rises 4–20 times the UNL.

AUTOMATION IN CLINICAL CHEMISTRY:

RANDOM ACCESS AUTOANALYZER

These kinds of completely automatic analyzers are best

suited for laboratories with moderate to heavy workload.

For a laboratory considering an automated clinical

chemistry system, there are a number of criteria, which are

very important to the Indian/tropical environment:

1. Design

2. Support

3. Cost.

Design

System design is an important factor and one should

answer questions as:

a. Does it have miles of tubing which can leak and which

will need replacing?

b. Is the dispensing mediated by banks of syringes which

can (and will) leak, and will need replacing?

c. Are the moving parts easily accessible?

d. Does the system need external drains?

e. Does the system need external water supplies?

f. Is the software open (can I change volumes, times,

etc.)?

g. Is the system open (can I use any reagent I like)?

h. Is the system flexible (can I do drugs, drug abuse in

urine—DAU, special proteins, and general developmental work, etc.)?

i. Is the system truly walkaway?

j. Can the system be interlinked with other equipment?

k. Can the system work with a data management system?

Support

Is the system supported in India by an organization with

true accountability, professionalism, and infrastructure

such that you can depend on getting help when you need it?

Cost

1. Capital cost of the equipment

2. Recurrent cost of reagents and consumables.

When looking at the cost of an instrument it is vital to

compare “like” with “like”. This means that it is important to

develop an understanding of the design feature differences

which can translate into very real benefits to the user. This

means in turn that one should not just compare quoted

prices on the assumption that one system is much like

another, they are not.

To summarize, when choosing an analyzer one should

think very seriously about the suitability of the equipment

to India. Issues of throughput, and unit price should not

distract the buyer from fundamentals of good design

because in the long run good design will save money.

Roche Hitachi 911 Chemistry Analyzer

(Courtesy: Recho Hitachi)

The Hitachi 911 is a fully automated, discrete, computerized

chemistry analyzer (Fig. 20.1) that uses serum, urine, plasma

and CSF sample types to perform in vitro quantitative and

qualitative tests on a wide range of alalytes. In addition, it

is capable of performing potentiometric and photometric

assays. The Hitachi 911 analyzer is composed of two units;