‫تهیه شده توسط‪ :‬پوهنیار خالد رضایی‬

Liver Function Test

 Liver Function Tests (LFTs)
1. LFTs are a group of tests that help in diagnosis, assessing prognosis and monitoring
therapy of liver diseases.
2. Each test assesses a specific aspect of liver function.
1. Synthetic function of the liver
2. Metabolic function of the liver (AA, Carbs, Lipids, Bilirubin
3. Detoxification function of the liver
4. Homeostasis (BGL)
5. Storage
6. Production of Bile
3. LFTs are often employed to determine
1. Presence of liver disease
2. Type of liver disease
3. Extent and progression of liver disease
4. Prothrombin time may be prolonged in acute disorders of the liver because of impaired
synthesis of coagulation factors.
 Tests of Excretion by the Liver
1. Bile Pigment
1. Serum Bilirubin concentration depends on the rate of removal of bilirubin from
destruction of hemoglobin
2. Bilirubin is conjugating by the liver and discarded through bile
3. Measuring serum and Urine bilirubin and urine Urobilinogen has clinical importance
4. Normal level of serum bilirubin is ≤ 1mg/dl
5. Increasing from 1mg/dl is known as Hyperbilirubinemia
6. If surpasses 2mg/dl known as Jaundice
7. Jaundice is Yellow discoloration of the skin and Sclera
1. Hemolytic Jaundice (Indirect Bile is increases)
2. Hepatocellur Jaundice (Direct and indirect will increase)
3. Obstructive Jaundice (direct increases)
 Bilirubin and Urobilinogen in Urine
1. Only direct bilirubin can be seen in obstructive jaundice
2. In pre-hepatic jaundice which indirect bilirubin increases its not seen.
3. In Obstructive Jaundice, bilirubin can not passes through bile ducts, Thus urobilinogen is
not produced to be seen in urine.
4. In Hepatocellular Jaundice Urobilinogen enhances primarily, if Obstruction occur, it
declines or disappears soon.
5. In hemolytic jaundice Urobilinogen increases.
6. If urobilinogen seen again in urine it shows the recovery of Obstruction.
 Evaluation of Synthesis in liver
1. Liver plays vital roles in synthesis of vital chemicals such as Protein synthesis,
Glucose, glycogen, Triglyceride, Fatty acids, cholesterol…
2. Liver has remarkable reserve capacity and prevents from serum protein reduction.
3. Additionally liver synthesis proteins have long half life.
4. Serum protein concentration depends on the type of liver injury.
1. Acute (long shelf-life proteins do not change but shorts half-life will changes)
 Serum Albumin
1. Almost all serum proteins synthesis by the liver except immunoglobulins.
2. Serum albumin measurements are useful in assessing the chronicity and severity of
liver disease.
3. The serum albumin concentration is decreased in chronic liver disease.
4. Albumin/Globulin >1
5. However, its utility for this purpose is somewhat limited, as the serum albumin
concentration is also decreased in:
1. Severe acute liver disease
2. Inflammatory disorders and Malnutrition, and with Nephrotic syndrome.
6. Serial measurements of serum albumin also are used to assess the severity o liver
disease.
 Prothrombin Time (PT)
1. PT measurements are used to determine synthetic liver function.
2. They are thought to be more reliable than albumin because fewer conditions (other than
warfarin administration) affect PT than affect albumin.
3. PT is the most important prognostic marker in acute liver disease and is usually the first
function test to become abnormal as chronic hepatitis evolves into cirrhosis.
4. PT will elongate when the liver loss 80% of it’s reserve capacity.
5. Low level of vit-K also will elongate PT.
6. PT is also one of the parameters used in calculating the MELD score, which is used to
predict need or transplantation in cirrhosis.
 Alfa fetoprotein (AFP)
1. Alfa fetoprotein is one of the normal components of fetal blood.
2. It will increase slightly in liver inflammation and liver cirrhosis but markedly in
hepatocellular carcinoma, germ cell tumor, teratoma of ovary.
Serum electrophoresis
1. Pre-albumin in acute livers diseases and Albumin in Liver Cirrhosis
2. Alpha-1 globulins includes Glycoproteins and Hormone binding proteins and reduce in
liver diseases and increase in Malignancies.
3. alpha-2 globulin and beta globulin high level is indicator of Bile duct obstruction.
 Detoxification Functions of the liver
1. The liver remove noxious materials or renders them harmless by conjugation of toxic
substances with AAs, glucoronate and inorganic radicals (Sulphate), by oxidation or
reduction, by excretion, etc.
HIPPURIC ACID TEST
1. This test depends upon conjugation by liver of sodium benzoate with glycine to produce
hippuric acid, which is excreted in the urine.
2. It is preferable to give sodium benzoate (1.77 gm I/V), one hour later at least 0.7 gm of
hippuric acid should be excreted in the urine.
3. Consideration of low values is permissible only if impaired renal function is ruled out
for retention of hippuric acid.
 Evaluation of enzyme activity
1. Enzymes which shows liver disease
2. Enzymes which shows the obstruction of bile ducts (cholestasis)
Enzymes shows Liver Disease
• Aspartate Aminotransferase (AST) (transferases or transaminase )
1. As it involves in transfer of an amino group between aspartate and Keto acids.
2. The older terminology, serum glutamic oxalo-acetic transaminase (SGOT, or
GOT), may also be used. (B6)
3. The transamination reaction is important in intermediary metabolism because of
its function in the synthesis and degradation of AAs.
4. The ketoacids ultimately oxidized by the TCA to provide a source of energy
 Tissue Source & Diagnostic Significance
1. Highest concentrations found in cardiac tissue, liver, and skeletal muscle, with smaller
amounts found in the kidney, pancreas, and RBCs.
2. The clinical use of AST is limited mainly to the evaluation of hepatocellular disorders
and skeletal muscle involvement.
3. In AMI, AST levels begin to rise within 6 to 8 hours, peak at 24 hours (normal 5 days).
4. As its wide tissue distribution, AST levels are not useful in the diagnosis of AMI and
LFT.
5. Following congestive heart failure, AST levels increased as a result of inadequate blood
supply of the liver.
6. AST levels are highest in acute hepatocellular disorders.
Cont…
1. In viral hepatitis, levels may reach 100 times.
2. In cirrhosis, only moderate levels (4 times) are detected
3. Skeletal muscle disorders and inflammatory conditions in AST levels (4 to 8 times).
4. AST exists as two isoenzyme fractions located in the cell cytoplasm and mitochondria.
5. The intracellular concentration of AST may be 7,000 times higher than the
extracellular concentration.
6. The cytoplasmic isoenzyme is the predominant form occurring in serum.
7. In disorders producing cellular necrosis, the mitochondrial form may be significantly
increased.
8. Isoenzyme analysis of AST is not routinely performed in the clinical laboratory.
 Alanine Aminotransferase & Tissue Sources

1. It catalyzes the transfer of an amino group from alanine to α-ketoglutarate with the
formation of glutamate and pyruvate.

2. Serum glutamic pyruvic transaminase (SGPT, or GPT). (B6)

3. ALT is distributed in many tissues, with comparatively high concentrations in the liver.

4. It is considered the more liver-specific enzyme of the transferases.

 Diagnostic Significance
1. Clinical applications of ALT are confined mainly to evaluation of hepatic disorders.
2. Higher elevations are found in hepatocellular disorders than in extrahepatic or
intrahepatic obstructive disorders.
3. ALT level is higher than AST and tend to remain elevated longer as a result of the
longer half-life of ALT in serum (16 and 24 hours, respectively).
4. Heart contains small amount of ALT, but remains normal in AMI unless subsequent
liver damage has occurred.
5. ALT levels have historically been compared with levels of AST to help determine the
source of an elevated AST level and to detect liver involvement concurrent with
myocardial injury.
 Enzymes Shows cholestasis
Alkaline Phosphatase (ALP) and Tissue Sources
1. ALP catalyze the hydrolysis of various phosphomonoesters at an alkaline pH.
2. It is a nonspecific enzyme capable of reacting with many different substrates.
3. Specifically, ALP functions to liberate inorganic phosphate from an organic phosphate
ester with the concomitant production of an alcohol.
4. The optimal pH for the reaction is 9.0 to 10.0, but optimal pH varies with the substrate
used. (Mg2+ as an activator)
5. ALP activity is present on cell surfaces in most human tissue.
6. The highest concentrations are found in the intestine, liver, bone, spleen, placenta, and
kidney.
7. In the liver, the enzyme is located on both sinusoidal and bile canalicular membranes.
 Cont…
1. Elevations of ALP are of most diagnostic significance in the evaluation of hepatobiliary
and bone disorders.
2. Elevations are more predominant in obstructive conditions than in hepatocellular disorders;
in bone disorders, elevations are observed when there is involvement of osteoblasts.
3. In biliary tract obstruction, ALP levels range from 3 to 10 times than normal.
4. Increases result by increased synthesis of the enzyme induced by cholestasis.
5. In contrast, hepatocellular disorders, such as hepatitis and cirrhosis, show only slight
increases, usually less than 3 times than normal.
6. Because of the degree of overlap of ALP elevations that occurs in the various liver
disorders, a single elevated ALP level is difficult to interpret.
7. It assumes more diagnostic significance when evaluated along with other tests of hepatic
function.
8. Elevated ALP levels may be observed in various bone disorders.
Cont…
1. The highest elevations of ALP activity occur in Paget’s disease.
2. Increased levels also are observed in healing bone fractures and during periods of
physiologic bone growth.
3. In normal pregnancy, increased ALP activity, averaging approximately 1½ times the
ULN, can be detected between weeks 16 and 20 and is 2 to 3 times the ULN during the
third trimester.
4. ALP activity increases and persists until the onset of labor.
1. Returns to normal within 3 to 6 days.
5. Elevations also may be seen in complications of pregnancy such as hypertension,
preeclampsia, and eclampsia, as well as in threatened abortion.
 Gamma Glutamyl Transferase (GGT)
1. GGT is an enzyme involved in the transfer of the γ-glutamyl residue from γ-
glutamyl peptides to amino acids, H2O, and other small peptides.
2. In most biologic systems, glutathione serves as the γ-glutamyl donor.
3. GGT is involves in peptide and protein synthesis, regulation of tissue glutathione
levels, and the transport of amino acids across cell membranes.
4. Kidney, brain, prostate, pancreas, and liver.
5. Clinical applications of assay, however, are confined mainly to evaluation of liver
and biliary system disorders.
 Diagnostic Significance
1. In the liver, GGT is located in the canaliculi of the hepatic cells and particularly in the
epithelial cells lining the biliary ductules.
2. GGT is elevated in virtually all hepatobiliary disorders, making it one of the most sensitive
of enzyme assays in these conditions.
3. Higher elevations are generally observed in biliary tract obstruction.
4. Within the hepatic parenchyma, GGT exists to a large extent in the SER.
5. Therefore, GGT levels will be increased in patients receiving enzyme-inducing drugs such
as warfarin, phenobarbital, and phenytoin.
6. Enzyme elevations may reach levels four times.
7. Because of the effects of alcohol on GGT activity, elevated GGT levels may indicate
alcoholism, particularly chronic alcoholism.
8. Generally, enzyme elevations in persons who are alcoholics or heavy drinkers range from
two to three times the ULN, although higher levels have been observed.
 Cont…
1. GGT levels are also elevated in other conditions, such as acute pancreatitis, diabetes
mellitus, and MI.
2. The source of elevation in pancreatitis and diabetes is probably the pancreas, but the
source of GGT in MI is unknown.
3. GGT assays are of limited value in the diagnosis of these conditions and are not routinely
requested.
4. GGT activity is useful in differentiating the source of an elevated ALP level because
GGT levels are normal in skeletal disorders and during pregnancy.
5. It is particularly useful in evaluating hepatobiliary involvement in adolescents because
ALP activity will invariably be elevated as a result of bone growth.
 5’-Nucleotidase
1. It known as nucleotide phosphatase (NTP) too.
2. Its level will increase same as ALP in biliary obstructions.
Test Selection
1. Bilirubin, AST, ALT, APL, GGT, Total protein, Albumin, Cholesterol level.
2. Generally ALT and ALP uses to differentiate between the biliary and
hepatocellular disorders.
3. Albumin for chronic disease recognition and PT to determine liver disorders
extend.
Kidney Function Test
(KFT)
 Analytic Procedures of Kidney
1. To assess Kidney Function
1. Glomerular function
1. Clearance Test
2. Glomerular permeability
1. Proteinuria
3. Tubular function
1. Specific gravity
1. Concentration Test
2. Dilution Test
2. To assess Kidney disease
1. Urea, Creatinine
2. Serum Electrolytes
3. Urinalysis
 Analytic Procedures of Kidney
1. All laboratory methods for evaluation of renal function rely on the measurement of waste products
in blood, usually urea and creatinine, which accumulate when the kidneys begin to fail.
2. Renal failure must be advanced, with only about 20% to 30% of the nephrons still functioning.
3. Clearance is that volume of plasma which a measured amount of substance can be completely
eliminated into the urine per unit of time expressed in ml/min.
4. Calculation of creatinine clearance has become the standard laboratory method for determining of
GFR.
5. Urea clearance it is no longer widely used, Older tests used administration of insulin, sodium [125I]
iothalamate, or p-aminohippurate to assess glomerular filtration or tubular secretion.
6. These tests are difficult to administer and are no longer common.
 Creatinine Clearance (CL)
1. Creatinine is a nearly ideal substance for the measurement of clearance.
2. It is an endogenous metabolic product synthesized at a constant rate for a given individual and
cleared essentially only by glomerular filtration.
3. It is not reabsorbed and is only slightly secreted by the proximal tubule.
4. Serum creatinine levels are higher in males than in females.
5. Analysis of creatinine is simple and inexpensive using colorimetric assays
1. different methods for assaying plasma creatinine, such as kinetic or enzymatic assays, have varying
degrees of accuracy and imprecision.
6. Creatinine clearance is derived by mathematically relating the serum creatinine concentration to
the urine creatinine concentration excreted during a period of time, usually 24 hours.
Cont…
1. Specimen collection, therefore, must include both a 24-hour urine specimen and a serum
creatinine value.
2. The urine container must be kept refrigerated throughout the duration of both the collection and
storage period.
3. The total volume of urine is carefully measured, and the creatinine clearance is calculated using
the following formula:
𝑈𝐶𝑟 (𝑚𝑔/𝑑𝐿) × 𝑉𝑢𝑟(𝑚𝐿/24ℎ𝑜𝑢𝑟𝑠) 1.73
4. CL= 𝑥
𝑃𝐶𝑟 (𝑚𝑔/𝑑𝐿) × 1,440 𝑚𝑖𝑛𝑢𝑡𝑒𝑠/24ℎ𝑜𝑢𝑟𝑠 𝐴
 Estimated GFR
1. The National Kidney Foundation recommends that estimated GFR (eGFR) be calculated each time a
serum creatinine level is reported.
2. The equation is used to predict GFR which is based on serum creatinine, age, body size, gender, and
race (No urine).
3. The calculation does not require a timed urine collection, it should be used more often than the
traditional creatinine clearance and result in earlier detection of chronic kidney disease (CKD).
4. There are a number of formulas that can be used to estimate GFR on the basis of serum creatinine
levels.
Cockcroft-Gault Formula

1. The Cockcroft-Gault formula is one of the first formulas used to estimate GFR.
2. This formula predicts creatinine clearance and the results are not corrected for body
surface area.
3. This equation assumes that women will have a 15% lower creatinine clearance than men at
the same level of serum creatinine.
(140−𝐴𝑔𝑒) × 𝑊𝑒𝑖𝑔ℎ𝑡(𝑘𝑔)
4. GFR (ml /min) = × (0.85 if female)
72 ×𝑃𝑐𝑟(𝑚𝑔/𝑑𝐿)
 Modification of Diet in Renal Disease (MDRD) Formula

1. This formula provided a more accurate assessment of GFR than the Cockcroft- Gault formula.
2. The MDRD formula was validated in a large population that included European Americans and
African Americans.
3. It does not require patient weight and is corrected for body surface area.
4. The MDRD formula is known to underestimate the GFR in healthy individuals with GFRs over
60 mL/min and to overestimate GFR in underweight patients.
5. The four-variable MDRD equation includes age, race, gender, and serum creatinine's variables.
6. GFR (mL /min/1.73 m2) = 186 × SCr(mg/dL)-1.154 × Age-0.203 × (1.212 if Black) × (0.742
if female)
CKD-EPI Formula

1. The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) formula was published in
2009.
2. It was developed in an effort to create a formula more accurate than the MDRD formula.
3. Multiple studies have shown that CKD-EPI formula to perform better with less bias than the
MDRD formula, especially in patients with higher GFR.
4. Most laboratories still use the MDRD formula; however, some have converted to the CKD-EPI
formula:
5. eGFR(mL /min/1.73 m2) = 141 × min (SCr/k,1)a × max(SCr/k,1)-1.209 × 0.993Age × (1.018 if
female) × (1.159 if Black)
6. Note: k is 0.7 for females and 0.9 for males, а is –0.329 for females and –0.411 for males, min
indicates the minimum of SCr/k or 1, and max indicates the maximum of SCr/k or 1.
 ꞵ2-Microglobulin
1. β2-Microglobulin (β2-M) is a small peptide found on the surface of most nucleated cells.
2. The plasma membrane sheds β2-M at a constant rate, as a relatively intact molecule.
3. β2-M is easily filtered by the glomerulus and 99.9% is reabsorbed by the proximal tubules.
4. It is not a routine test and used to differentiate glomerulus and tubular damage.
5. Elevated levels in serum indicate increased cellular turnover as seen in myeloproliferative and
lymphoproliferative disorders, inflammation, and renal failure.
6. Both blood and urine β2-M tests may be ordered to evaluate kidney damage and to distinguish
between disorders that affect the glomeruli and the renal tubules.
7. Measurement of serum β2-M is used clinically to assess renal tubular function in renal transplant
patients, with elevated levels indicating organ rejection.
 Cystatin C or Cystatin 3
1. Cystatin C is a low-molecular-weight protein produced at a steady rate by most body tissues.
2. It is freely filtered by the glomerulus, reabsorbed, and catabolized by the proximal tubule.
3. Levels of cystatin C rise more quickly than creatinine levels in acute renal failure.
4. Plasma concentrations appear to be unaffected by diet, gender, race, age, and muscle mass.
5. Studies have shown measurement of cystatin C to be at least as useful as serum creatinine and
creatinine clearance in detecting early changes in kidney function.
6. A rise in cystatin C is often detectable before there is a measureable decrease in the GFR or
increase in creatinine.
7. It is a potent inhibitor of lysosomal proteinases and Extracellular inhibitor of Cysteine proteases.
8. Recent findings suggest that an equation that uses both serum creatinine and cystatin C with age,
sex, and race would be better than equations that use only one of these serum markers.
 Myoglobin
1. it is a low-molecular-weight protein associated with acute skeletal and cardiac muscle injury.
2. Myoglobin functions to bind and transport O2 from the plasma membrane to the mitochondria in
muscle cells.
3. Blood level rise very quickly with severe muscle injury.
4. In rhabdomyolysis, myoglobin release from skeletal muscle, is sufficient to overload the proximal
tubules and cause acute renal failure.
5. Early diagnosis and aggressive treatment of elevated myoglobin may prevent or lessen the
severity of renal failure.
6. Serum and urine myoglobin can be measured easily and rapidly by immunoassays.
 Microalbuminuria
1. The term microalbuminuria describes small amounts of albumin in the urine.
2. Urine microalbumin measurement is important in the management of patients with diabetes
mellitus.
3. Who are at serious risk for developing nephropathy over their lifetime.
4. In the early stages of nephropathy, there is renal hypertrophy, hyperfunction, and increased
thickness of the glomerular and tubular basement membranes.
5. In this early stage, there are no overt signs of renal dysfunction.
6. In the next 7 to 10 years, there is progression to glomerulosclerosis, with increased glomerular
capillary permeability.
7. This permeability allows small (micro) amounts of albumin to pass into the urine.
8. If detected in this early phase, rigid glucose control, along with treatment to prevent hypertension,
can be instituted and progression to kidney failure prevented.
 Cont…
1. For a 24-hour urine collection, 30 to 300 mg of albumin is diagnostic of microalbuminuria.
2. A 24-hour urine collection is preferred, but a random urine sample that uses a ratio of albumin to
creatinine can also be used.
3. An albumin to creatinine ratio of >30 mg/g is diagnostic of microalbuminuria.
Urinalysis (UA)
1. UA permits a detailed, in-depth assessment of renal status with an easily obtained specimen.
2. UA also serves as a quick indicator of an individual’s glucose status and hepatic–biliary function.
3. Routine UA includes assessment of physical characteristics, chemical analyses, and a microscopic
examination of the sediment from a (random) urine specimen.
 Overview of some inborn errors of metabolism
Phenylketonuria (PKU)
1. PKU is the most common clinically encountered inborn error of amino acid metabolism (PAH
deficiency).
2. It characterized by hyperphenylalaninemia.
3. Phenylalanine is present in high concentrations in plasma, urine and body tissues.
4. Tyrosine, which normally is formed from phenylalanine by PAH, is deficient (Hypopigmentation).
5. Treatment includes dietary restriction of phenylalanine and supplementation with tyrosine.
6. [Note: Hyperphenylalaninemia may also be caused by rare deficiencies in any of the several
enzymes required to synthesize BH4 or in dihydropteridine reductase, which regenerates BH4 from
BH2.
7. Such deficiencies indirectly raise phenylalanine concentrations, because PAH requires BH4 as a
coenzyme.
Cont…
1. BH4 is also required for tyrosine hydroxylase and tryptophan hydroxylase, which catalyze
reactions leading to the synthesis of neurotransmitters (serotonin and the catecholamines).
2. Simply restricting dietary phenylalanine does not reverse the CNS effects due to deficiencies in
neurotransmitters.
3. Supplementation with BH4 and replacement therapy with L-3,4- dihydroxyphenylalanine and 5-
hydroxytryptophan improves the clinical outcome in these variant forms of
hyperphenylalaninemia.
1. Additional characteristics
a.
1. PKU is also characterized by elevated levels of a phenylketone in the urine.
2.Elevated phenylalanine metabolites: Phenylpyruvate, phenylacetate, and phenyllactate, which are
not normally produced in significant amounts in the presence of functional PAH, are elevated in
PKU.
3. These metabolites give urine a characteristic musty (“mousy”) odor.
b.
1. CNS effects: Severe intellectual disability, developmental delay, microcephaly, and seizures are
characteristic findings in untreated PKU.
2. The affected individual typically shows symptoms of intellectual disability by age 1 year and
rarely achieves an intelligence quotient (IQ) >50.
3. These clinical manifestations are now rarely seen as a result of newborn screening programs,
which allow early diagnosis and treatment.
1. Additional characteristics
Hypopigmentation
1. Patients with untreated PKU may show a deficiency of pigmentation (fair hair, light skin color,
and blue eyes).
2. The hydroxylation of tyrosine by copper-requiring tyrosinase, which is the first step in the
formation of the melanin, is decreased in PKU because tyrosine is decreased.
Maple syrup urine disease (MSUD)
1. MSUD is a rare (1:185,000) disorder in which there is a partial or complete deficiency in BCKD.
2. It is a mitochondrial enzyme that oxidatively decarboxylates leucine, isoleucine, and valine.
3. These BCAA and their corresponding α-keto acids accumulate in the blood, causing a toxic effect
that interferes with brain functions.
4. The disease is characterized by
1. Feeding problems, vomiting, ketoacidosis, changes in muscle tone, neurologic problems that can result in
coma, and a characteristic maple syrup–like odor of the urine because of the rise n isoleucine.
5. If untreated, the disease is fatal.
6. If treatment is delayed, intellectual disability results.
Albinism
1. There is a defect in tyrosine metabolism which decline melanin production.
2. It leads to partial or full absence of pigment from the skin, hair, and eyes.
3. Total absence of pigment from the hair, eyes, and skin, tyrosinase-negative oculocutaneous
albinism, results from an absent or defective copper-requiring tyrosinase.
4. It is the most severe form of the condition.
5. In addition to hypopigmentation, affected individuals have vision defects and photophobia.
6. They are at increased risk for skin cancer.
Cont…
Homocystinuria
1. They are a group of disorders affects Hcy metabolism.
2. It characterized by high urinary levels of Hcy, high plasma levels of Hcy and methionine, and
low plasma levels of cysteine.
3. There is a defect in the enzyme cystathionine β-synthase, which converts Hcy to cystathionine.
4. Cystathionine β-synthase deficiency exhibit dislocation of the lens, skeletal anomalies,
intellectual disability, and an increased risk for developing thrombi.
5. Thrombosis is the major cause of early death in these individuals.
6. Treatment includes restriction of methionine and supplementation with vitamin B12 and B9.
7. Additionally, some patients are responsive to oral administration of B6, the coenzyme of
cystathionine β-synthase.
Cont…
1. These patients usually have a milder and later onset
of clinical symptoms compared with B6
nonresponsive patients.
2. Deficiencies in B12 or N5,N10-THF reductase also
result in elevated Hcy.
Alkaptonuria
1. It Is due to deficiency in homogentisic acid oxidase, resulting in the accumulation of
homogentisic acid (HA), an intermediate in the degradative pathway of tyrosine.
2. The condition has three characteristic symptoms: homogentisic aciduria (Oxidized to a dark
pigment on standing, early onset of arthritis in the large joints, and deposition of black pigment
(ochronosis) in cartilage and collagenous tissue.
3. Dark staining of diapers can indicate the disease in infants, but usually no symptoms are present
until about age 40 years.
4. Treatment includes dietary restriction of phenylalanine and tyrosine to reduce HA levels.
5. Although alkaptonuria is not life threatening, the associated arthritis may be severely crippling.
6. [Note: Deficiencies in fumarylacetoacetate hydrolase, the terminal enzyme of tyrosine
metabolism, result in tyrosinemia type I and a characteristic cabbage-like odor to urine.]
Gaucher’s Disease
1. This is an inborn error of metabolism due to failure of degradation of glucocerebrosides.
2. The enzyme beta glucosidase is deficient in this condition.
3. This enzyme is responsible for breaking down a fatty substance called glucocerebroside in the
body.
4. When the enzyme is deficient, glucocerebroside accumulates in certain cells, particularly in the
spleen, liver, bone marrow, and sometimes the CNS.
5. Gaucher disease is inherited in an autosomal recessive pattern, meaning both parents must carry
the defective gene for a child to develop the disorder. There are three main types:
1. Type 1 (Non-neuropathic): The most common form, affecting the spleen, liver, and bones. It does not
involve the central nervous system.
2. Type 2 (Acute neuropathic): A more severe form that affects the central nervous system, often leading
to early death in infancy or early childhood.
3. Type 3 (Chronic neuropathic): A slower-progressing form that involves the brain and can appear
during childhood or adolescence.
Cardiac Biomarkers
1. A biomarker is a clinical laboratory test useful in detecting dysfunction of an organ.
2. Cardiac biomarkers are used to detect cardiac diseases, which may be:
a. Acute coronary syndrome resulting from myocardial ischemia
b. Congestive cardiac failure due to ventricular dysfunction
The different markers are used to:
1. Detect myocardial ischemia at the earliest
2. Monitor the progression of the condition
3. Predict the risk in cardiac dysfunction.
Any chest pain
Unstable angina
Suspicious ECG changes
History suggestive of myocardial infarction
Following surgical coronary revascularization
Patients with hypotension and dyspnea
Cont…
1. Commonly used biomarkers for early detection of acute myocardial infarction are:
2. Cardiac troponins, TnI and TnT, Creatine kinase, CK-MB.
3. Of these, troponins and CK-MB are the most sensitive and specific markers, whereas myoglobin
though sensitive, is nonspecific.
4. Predictors of risk in cardiac disease are of two types:
a. For predicting the onset of ischemia
b. Those which quantify the ventricular damage.
5. The risk predictors mainly include the atherogenic lipoproteins in plasma along with the
inflammatory marker like hsCRP (high sensitive CRP).
 Creatine Kinase (CK)
1. It was called as creatine phosphokinase (CPK) in old literature.
2. Normal serum value for CK is 15–100 U/L for males and 10–80 U/L for females.
CK and Heart Attack
1. CK value in serum is increased in myocardial infarction.
2. The CK level starts to rise within 3–6 hours of infarction.
3. CK estimation is very useful to detect early cases, where ECG changes may be ambiguous.
4. A 2nd peak may indicate another ischemic episode.
5. The CK level is not increased in hemolysis or in congestive cardiac failure; and therefore
CK has an advantage over LDH.
6. The area under the peak and slope of initial rise are proportional to the size of infarct.
Iso-enzymes of CK

1. CK is a dimer; each subunit has a molecular weight of 40 kD.

2. The subunits are called B for brain and M for muscle.
3. Therefore, three iso-enzymes are seen in circulation.
4. Normally CK2 (heart iso-enzyme) is only 5% of the total activity.
5. CK-MB iso-enzyme may not be detected, if total value of CK alone is estimated.
6. Hence the estimation of MB-isoenzyme is the best diagnostic marker in myocardial
infarction.
 CK and Muscle Diseases
1. The serum level of CK is very much elevated in muscular dystrophies (500–
1500 IU/L)
2. In female carriers of X-linked muscular dystrophy (heterozygous), CK is
moderately raised.
3. CK level is highly elevated in crush injury, fracture and acute
cerebrovascular accidents.
4. Estimation of total CK is employed in muscular dystrophies and MB iso-
enzyme is estimated in MI.
Cardiac Troponins (CTI/CTT)
1. Troponins are accepted as specific markers for myocardial infarction.
2. Measurement of cardiac troponins has become one of the main tests in early detection of
an ischemic episode and in monitoring the patient.
3. The troponin complex consists of 3 components;
1. Troponin C (calcium binding subunit), Troponin I (actomyosin ATPase inhibitory
subunit), Troponin T (tropomyosin binding subunit).
2. Troponin I (TnI) is encoded by 3 different genes, giving rise to 3 Isoforms; the "slow"
and "fast" moving forms are skeletal variety.
3. Cardiac isoform is specific for cardiac muscle; the AA sequence is different in skeletal
muscle isoform.
4. Cardiac isoform of cTnT and cTnI are mainly (95%) located in myofibrils and the
remaining 5% is cytoplasmic.
5. Circulating isoforms may be ternary complexes (TIC) or binary complexes (IC) or free
subunits of I and T.
6. They are generally identified and quantitated by immunological (ELISA or
immunoturbidimetric) reactions.
7. Troponins are seen in skeletal and cardiac muscles, but not in smooth muscles.
Cardiac Troponins (cTI/CTT)
1. cTnI is released into the blood within 4 hrs after the onset of symptoms of myocardial
ischemia;
2. Peaks at 14–24 hrs and remains elevated for 3–5 days post infarction.
3. Therefore, CTI is very useful as a marker at any time interval after the heart attack.
4. It is not increased in muscle injury; whereas CK2 may be elevated in some muscle injury.
5. The initial increase is due to liberation of the cytoplasmic fraction and sustained elevation is
due to the release from myofibrils.
6. Serum level of Troponin T (TnT) increases within 6 hrs of MI, peaks at 72 hrs and then
remains elevated up to 10–14 days.
7. Cardiac troponin elevations at lower concentrations than the 99th percentile value used for
MI
8. Diagnosis may identify patients who have not had an MI but still have a risk of having an
adverse cardiac event.
Cont…
1. Elevated cTn levels indicate cardiac injury, including acute coronary syndrome (ACS),
stroke, pulmonary embolism, sepsis, acute perimyocarditis, acute heart failure, and
tachycardia.
2. It enables determination of very low cTn concentrations.
3. The higher sensitivity of this assay has allowed for improved identification of patients
with AMI presenting in the first 3 hour following symptom onset.
4. Two measurements of hsTnT are required for the assessment of patients with chest pain;
the first measurement should be at presentation and the second sample should be
measured 6 hours later.
5. However, if the second sample does not show an incremental rise yet and clinical
suspicion remains, then a further sample should be taken 12 hours after presentation.
6. A rise of 20–100% is equivocal and needs further evaluation.
7. Greater than 100% rise is consistent with MI.
8. Increase may not be seen if patients present 24 hours after development of symptoms.
9. Concentrations of hs-cTnT>4 ng/L improve the prediction of death but not subsequent
AMI in unselected patients presenting with acute chest pain.
Lactate Dehydrogenase (LDH or LD)
1. The LDH will convert pyruvate to lactate.
2. Normal value of LDH in serum is 100–200 U/L.
3. Values in the upper range are generally, seen in children, Strenuous exercise will slightly
increase the value.
4. LDH level is 100 times more inside the RBC than in plasma, and therefore minor amount of
hemolysis will result in a false positive test.
LDH and Heart Attack
1. In MI, total LDH activity is increased, while H4 isoenzyme is increased 5–10 times more.
2. The magnitude of the peak value as well as the area under the graph will be roughly
proportional to the size of the MI.
Differential Diagnosis
1. Increase in total LDH level is seen in hemolytic anemias, hepatocellular damage, muscular
dystrophy, carcinomas, leukemias, and any condition which causes necrosis of body cells.
2. Since total LDH is increased in many conditions, the study of iso-enzymes of LDH is of great
importance.
Iso-enzymes of LDH
1. It is a tetramer with 4 subunits. But the subunit may be either H (heart) or M (muscle) polypeptide
chains.
2. Although both of them have the same molecular weight (32 kD), there are minor AAs variations.
3. So, 5 combinations of H and M chains are possible; H4, H3M, H2M2, M3H and M4 varieties, forming
5 iso-enzymes.
4. All these 5 forms are seen in all persons. The iso-enzymes are usually separated by electrophoresis at
pH 8.6
5. The bands are identified by adding the reactants NAD+, phenazine methosulphate) finally producing a
color reaction (with nitroblue tetrazolium) which may be quantitated by a scanner.
6. M4 form is seen in skeletal muscles while H4 form is seen in heart.
7. Normally LDH-2 (H3M1) concentration in blood is greater than LDH-1 (H4); but this pattern is
reversed in MI; this is called flipped pattern.
Brain Natriuretic Peptide (BNP)

1. The natriuretic peptide family consists of three peptides: Atrial natriuretic peptide
(ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP).
2. The clinical significance of CNP is not clear.
3. ANP is produced primarily in the cardiac atria.
4. BNP is present in human brain, but more in the cardiac ventricles.
5. Human pro-BNP contains 108 AAs.
6. It is cleaved by enzymes within cardiac myocytes into the active C-terminal BNP (32
AAs) and an inactive peptide (pro-BNP 1–76).
7. Both are seen in circulation.
8. These natriuretic peptides defend against excess salt and water retention.
Cont…
1. Congestive heart failure leads to high plasma concentrations of ANP and BNP (extent of
ventricular dysfunction).
2. High concentrations of BNP predict poor long-term survival.
3. In breathlessness, BNP test helps in the differentiation of the cause as heart failure or obstructive
lung disease.
4. Patients with COPD and worsening of their cor pulmonale with signs of RV volume overload had
increased BNP levels, and, indeed, these patients had increased mortality.
5. The best marker of ventricular dysfunction is pro-BNP.
6. Kits are available to assess BNP as well as the amino terminal of the pro-hormone (NT-proBNP).
7. Normal level of NT-proBNP is > 400 ng/L.
8. Less than 250 ng make heart failure highly unlikely.
9. BNP and NT-proBNP are released by the cardiac muscle in response to various stimuli, such as
increased cardiac wall tension from pressure and volume overload in the heart.
10. The system has a strong diuretic effect, promotes vasodilation, and facilitates cardiovascular
remodeling and response to ischemia.
 Other Markers for Myocardial Infarction
1. Myoglobin is raised after MI; but it is not specific and is raised during various other
conditions including muscle injuries.
1. It has the advantage of responding very rapidly, rising and falling earlier than CK-MB or
troponin.
2. A negative value will exclude infarction, and is useful in the early hours of chest pain
2. Myeloperoxidase (MPO) is a biomarker of inflammation and oxidative stress produced by
neutrophils, monocytes, and endothelial cells.
3. Concentrations of MPO predict mortality in patients with chronic heart failure.
4. MPO has been shown to consume endothelial-derived nitric oxide, to convert LDLs to their
proatherogenic forms, and to counteract the antiatherogenic effects of HDLs, thus propagating
the development of atherosclerosis.
5. MPO is an indicator of higher mortality in MI patients.
Cont…
1. Ischemia modified albumin (IMA)
1. Is another candidate cardiac marker. Myocardial ischemia alters the N-terminus of albumin
reducing the ability of cobalt to bind to albumin.
2. IMA measures ischemia in the blood vessels and thus returns results in minutes rather than
traditional markers of necrosis that take hours.
3. It has low specificity; therefore generating high number of false positives. A negative value is
highly useful, as it rules out the possibility of MI.
2. Glycogen phosphorylase iso-enzyme BB (GPBB) is an isoenzyme of glycogen phosphorylase.
1. Glycogen phosphorylase exists in 3 isoforms.
2. The GP-BB isoform exists in heart and brain tissue.
3. During ischemia, GP-BB is converted into a soluble form and is released into the blood.
4. A rapid rise in blood levels can be seen in myocardial infarction and unstable angina.
5. GP-BB elevated 1–3 hours after process of ischemia.
3. Pregnancy-associated plasma protein A (PAPP-A)
1. Increased PAPP-A in circulation correlates with poor outcome in acute coronary syndrome (ACS)
and in stable coronary artery disease.
2. PAPP-A is a zinc metalloproteinase.
3. Increased PAPP-A has been shown with poor prognosis in ACS or MI patients who remained TnI
negative.
4. Recently diagnostic Nano chips are being developed, which can identify the heart attack
within minutes.
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