LFT and RFT Handout by Refisa.pdf for wollegga

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1. Diagnostic Tests:
Liver Function Tests(LFT)



By: Refisa Shifera (B.Pharm, MSc)
June,2024
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2. LIVER FUNCTION TESTS (LFT)
•Liver is the largest and most complex internal organ of the body.
• The weight of liver is about 1.5kg.
•It is located below the diaphragm in the right upper quadrant of the
abdominal cavity.
•All blood flows from intestine and pancreas and reaches liver via
portal venous system.
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3. FUNCTIONS OF LIVER
•Liver is a multifunctional organ that is involved in diverse body
functions.
1. Metabolic Functions
•Liver actively participates in carbohydrate metabolism, lipid, protein,
mineral and vitamin metabolisms.
2. Excretory Functions
•Bile pigments, bile salts and cholesterol are excreted in bile into
intestine.
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4. 3. Protective functions & detoxification
•Kupffer cells of liver perform phagocytosis to eliminate foreign
compounds. For example ammonia is detoxified to urea and
metabolism of xenobiotics (detoxification).
•Clearance of hormones such as insulin, parathyroid hormone,
oestrogen, cortisol
4. Hematological and synthetic functions
•Liver participates in formation of blood (particularly in embryo).
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5.  Synthesis of plasma proteins (albumin and prothrombin), hormones
e.g angiotensinogen, insulin-like growth factor and triiodothyronine.
Destruction of erythrocytes (Bilirubin).
5. Storage functions
Glycogen, vitamins A, D and B12
6. Production of bile salts
Helps in digestion
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6. Some example of liver dysfunction
•Hepatocellular disease
•Cholestasis (obstruction of bile flow)
•Cirrhosis
•Hepatitis
•Jaundice
•Liver cancer
•Steatosis (fatty liver)
•Genetic Disorders
▫ Hemochromatosis (iron storage)
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7. Liver Function Tests (LFTs)
•It is a non-invasive methods for screening of liver
dysfunction
• Help in identifying general types of disorder
•Assess severity and allow prediction of outcome
•Disease and treatment follow up
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8. Classification of LFTs
•Liver function tests are broadly classified into following groups
according to their functions:-
•Group I —Tests of hepatic excretory function
i. Serum—Bilirubin; total, conjugated, and unconjugated.
ii. Urine—Bile pigments, bile salts and urobilinogen.
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9. •Group II—Markers of liver injury
i. Alanine amino transferase (ALT)
ii. Aspartate amino transferase (AST)
iii. Alkaline phosphatase (ALP)
iv. Gamma glutamyl transferase (GGT)
•Group III—Tests for synthetic function of liver
i. Total proteins
ii. Serum albumin, globulins, A/G ratio
iii. Prothrombin time
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10. 1. BILIRUBIN
•A by-product of red blood cell breakdown.
•It is conjugated by the liver to form bilirubin diglucuronide and
excreted through bile.
•It is the yellowish pigment observed in jaundice
•High bilirubin levels are observed in:
 Gallstones, acute and chronic hepatitis
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15. PLASMA BILIRUBIN
• Normal plasma bilirubin: 0.2–0.8 mg/dl.
Unconjugated bilirubin: 0.2–0.6 mg/dl.
Conjugated bilirubin: 0–0.2 mg/dl.
If the plasma bilirubin level exceeds 1mg/dl, the condition is called
hyperbilirubinemia.
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16. Levels between 1 & 2 mg/dl are indicative of latent
jaundice.
When the bilirubin level exceeds 2 mg/dl, it diffuses into
tissues producing yellowish discoloration of sclera,
conjunctiva, skin & mucous membrane resulting in jaundice.
Icterus is the Greek term for jaundice.
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17. Van den Bergh Test
 It is a specific test for identification of increased serum
bilirubin levels.
Normal serum gives a negative van den Bergh reaction.
Mechanism of the reaction:
Van den Bergh reagent is a mixture of equal volumes of
sulfanilic acid (in dilute HCI)& sodium nitrite.
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18. Principle:
•Diazotised sulfanilic acid reacts with bilirubin to form a purple
coloured azobilirubin.
Direct and indirect reactions:
•Bilirubin as such is insoluble in water while the conjugated bilirubin is
soluble.
•Bilirubin shows direct, indirect and mixed reactions according to its
unconjugated and conjugated state.
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19. •Van den Bergh reagent reacts with conjugated bilirubin & gives a
purple colour immediately (normally within 30 seconds).
- This is direct positive van den Bergh reaction.
•Addition of methanol (or alcohol) dissolves the unconjugated
bilirubin & gives the van den Bergh reaction (normally within 30
minutes) positive.
- This is indirect positive van den bergh reaction
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20. • lf the serum contains both unconjugated and conjugated bilirubin in
high concentration, the purple colour is produced immediately (direct
positive) which is further intensified by the addition of alcohol
(indirect positive).
- This type of reaction is known as biphasic.
•Van den berg test and Jaundice
 Useful in understanding the nature of jaundice.
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21. •This is due to jaundice is characterized by increased serum
concentration of unconjugated bilirubin (hemolytic),
conjugated bilirubin (obstructive) or both of them (hepatic).
•Indirect positive - Hemolytic jaundice
•Direct positive - Obstructive jaundice
•Biphasic - Hepatic jaundice
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22. Bilirubin in Urine
Normally bilirubin is absent in urine.
Conjugated bilirubin being water soluble is excreted in urine in
obstructive jaundice.
This can be detected by Fouchet’s test
In prehepatic jaundice, when the unconjugated bilirubin is increased in
blood, it does not appear in urine; hence called acholuric jaundice.
•In obstructive jaundice, urine contains bilirubin; hence in old literature,
it is called choluric jaundice.
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23. Urobilinogen (UBG) and bile salts
•Most UBG is metabolized in the large intestine but a
fraction is excreted in urine (less than 4 mg/day).
•Urobilinogen is detected by Ehrlich's test.
• Normally bile salts are NOT present in urine
•Obstruction in the biliary passages causes:
Leakage of bile salts into circulation, Excretion in urine.


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24. •Bilirubin cannot enter intestine.
•Note: Presence of bilirubin in urine and absence of
urobilinogen in urine is seen in obstructive jaundice.
•Note: Increased urobilinogen in urine and absence of
bilirubin in urine is seen in hemolytic jaundice.
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25. •Fecal urobilinogen - Normal about 300mg.
•Increased in Hemolytic jaundice in which color of feces is
dark.
•In Obstructive jaundice urobilinogen is not excreted
through feces and the color is the feces is pale.
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26. Jaundice
Jaundice is yellow discolouration of conjunctivae , mucous
membrane and skin due to increased bilirubin level.
Clinical jaundice appears when bilirubin concentration is
more than 3 mg/dl.
•Levels between 1 and 3 mg/dl is sub-clinical jaundice.
•Classification of Jaundice:
•Jaundice is classified into three types:
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27. 1. Prehepatic or Hemolytic jaundice
In this, there is increased breakdown of Hb, so that liver
cells are unable to conjugate all the increased bilirubin
formed.
Causes :
Increased production of unconjugated bilirubin from:
hemolysis - sickle cell anemia
Rapid turnover of RBC - Neonate
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28. oPhysiological jaundice (Bilirubin 5mg/dl).
oKernicterus Bilirubin >20mg/dl.
oBrain damage due to entry of bilirubin.
o No blood brain barrier.
Decreased uptake of bilirubin by hepatocyte -
Gilbert syndrome.
Decreased conjugation - Neonatal Jaundice, drug inhibition
, crigler – najjar syndrome, Hepatocellular dysfunction.
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29. 2.Obstructive jaundice or Post hepatic jaundice
•In this, there is obstruction to the flow of bile in the extra
hepatic ducts.
Decreased secretion of conjugated bilirubin into canaliculi -
Hepatocellular disease, hepatitis.
Decreased drainage -Intrahepatic obstruction by drugs , cirrhosis.
Extra hepatic obstruction - stones , Carcinoma.
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30. 3.Hepatocellular or hepatic jaundice
•In this, there is disease of the parenchymal cell of liver.
Causes:-
•Acute hepatitis is usually caused by viral infections e.g.
Hepatitis A, C, D, E
• or by toxins eg: paracetamol, Carbon tetrachloride etc.

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33. 33

34. TESTS BASED ON SYNTHETIC
FUNCTION OF LIVER
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35. 1.SERUM ALBUMIN
•The most abundant protein synthesized by the liver
•Normal serum levels: 3.5 – 5 g/dL.
•Synthesis depends on the extent of functioning liver cell
mass
•Longer half-life: 20 days
•Its levels decrease in all chronic liver diseases
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36. 2.SERUM GLOBULIN
Normal serum levels: 2.5 – 3.5g/dL
Alpha and Beta-globulins mainly synthesized by the liver
They constitute immunoglobulins (antibodies)
High serum gamma-globulins are observed in chronic
hepatitis and cirrhosis:
–IgG in autoimmune hepatitis
–IgA in alcoholic liver disease
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37. 3.Prothrombin
•synthesized by the liver, a marker of liver function
•Half-life: 6 hrs. (indicates the present function of the liver)
•Normal Prothrombin Time = 11 to 12 seconds
•PT is prolonged only when liver loses more than 80% of its
reserve capacity
•Vitamin K deficiency also causes prolonged PT
•Intake of vitamin K does not affect PT in liver disease.
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38. 4.α-Fetoprotein (AFP)
One of the major plasma proteins in foetal life.
In acute hepatic injury AFP increase 10 – 20X upper ref
limits.
About 10% patient with viral hepatitis have increase AFP
Fibrosis post chronic liver disease, AFP increase
Used to screen and diagnose HCC & hepatoblastoma.
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39. TESTS BASED ON
SERUM ENZYMES

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40. 1. ALANINE AMINO TRANSFERASE
•ALT or SGPT (serum glutamate pyruvate transaminase)
•ALT is a cytoplasmic enzyme.
•Normal Range: 10- 35 U/L.
•The test is primarily used to diagnose liver disease, to
monitor the course of treatment for hepatitis, active
postnecrotic cirrhosis, and the effect of drug therapy.
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41.  More liver-specific than AST
High serum levels in acute hepatitis (300-1000U/L)
Moderate elevation in alcoholic hepatitis and nonalcoholic
chronic hepatitis (100-300U/L) .
Minor elevation in cirrhosis, chronic hepatitis (50-100U/L).
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42. 2.Aspartate Aminotransferase (AST)
AST or SGOT (serum glutamate oxaloacetate transaminase)
AST is found in both cytoplasm & mitochondria
Also reflects damage to the hepatic cell
•It is less specific for liver disease
•It may be elevated and other conditions such as a
myocardial infarct and muscle disease.
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43. •Normal range: 8 – 20 U/L
•A marker of hepatocellular damage
•High serum levels are observed in:
–Chronic hepatitis, cirrhosis and liver cancer
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46. 3. Alkaline phosphatase (ALP)
•A non-specific marker of liver disease
•Produced by bone osteoblasts (for bone calcification)
•Present on hepatocyte membrane
•Normal range: 40 – 125 U/L
•Moderate elevation observed in:
–Infective hepatitis, alcoholic hepatitis and hepatocellular
carcinoma
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47. •High levels are observed in:
–Extrahepatic obstruction (obstructive jaundice) and
intrahepatic cholestasis
•Very high levels are observed in:
–Bone diseases
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51. 4.γ-Glutamyl transpeptidase (GGT)
 It is a membrane bound glycoprotein which catalyses the
transfer of γ- glutamyl group to other peptides and AAS.
GGT is used by the body to synthesize glutathione tri
peptide.
This is a microsomal enzyme widely distributed in body
tissues, including liver.
•Very useful in diagnosis of obstructive jaundice. (not
elevated in bone diseases)
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52. • Normal range: 10 – 30U/L
•Moderate elevation observed in:
–Infective hepatitis and prostate cancers
oGGT is increased in alcoholics despite normal liver
function tests
–Highly sensitive to detecting alcohol abuse
oIn liver diseases, GGT elevation parallels that of ALP.
oIn alcoholic liver disease, GGT levels may be parallel to
alcohol intake.
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57. OTHER TESTS
oTests based on metabolic capacity – Galactose tolerance,
antipyrine clearance.
oTests based on detoxification - Hippuric acid synthesis.
Special tests:
Blood ammonia
α1- antitrypsin
Immunoglobulins
Ceruloplasmin
Ferritin
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59. Diagnostic Tests:
Renal Function Tests

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60. Nephron
-The nephron is the functional unit of the kidney.
-Each kidney contains about 1,000,000 to 1,300,000 nephrons.
-The nephron is composed of glomerulus and renal tubules.
-The nephron performs its homeostatic function by ultra filtration at
glomerulus and secretion and reabsorption at renal tubules.
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61. Kidney functions
★Regulation of :
•water and electrolyte balance controlled by aldosterone.
•acid base balance by excreting acids and by regulating
the body fluid buffer stores.
• arterial blood pressure controlled by RAAS.
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62. ★Excretion of :
•metabolic waste products metabolic wastes will be
converted to intoxic (inactive) metabolites in the liver
(catabolism reaction), then excreted in the urine by the
kidney.
•foreign chemicals.
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63. ★Hormonal Function :
- Secretion of erythropoietin which stimulates the production of RBCs by
hematopoietic stem cells in the bone marrow.
- activation of vitamin D the kidneys convert vitamin D to its active form
which is 1,25-dihydroxyvitamin D3 (calcitriol) with the help of 1-α-
hydroxylase enzyme .
- activation of angiotensinogen by renin a hormone system that
regulates blood pressure, fluid and electrolyte balance, as well as
systemic vascular resistance.
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64. ★Metabolic Function :
•- site for gluconeogenesis The kidneys synthesize glucose
from amino acids and other non-carbohydrate precursors
during prolonged fasting along with the liver, a process
•referred to as gluconeogenesis.
Each nephron is a complex apparatus comprised of five
basic parts:

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67. Why test the renal functions ?
•Many diseases affect renal function.
•In some, several functions are affected.
•In others, there is selective impairment of glomerular
function or one or more of tubular functions.
•Most types of renal diseases cause destruction of complete
nephron.
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69. Measurements of GFR
•The glomerular filtration rate (GFR) provides a useful
index of the number of functioning glomeruli.
- It gives an estimation of the degree of renal impairment by
disease.
- Accurate measurement of GFR by clearance tests requires
determination of the concentration in plasma and urine of a
substance that is:
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73. e.g. if we eat meat it won’t rise the creatinine levels in our plasma, because it will
be degraded and may be excreted in the feces. that's why sCr is a good marker
because it's ENDOGENOUS.
Means the creatinine is freely filtered at the glomerulus but it’s secreted by PCT
about 10% so if they wanna calculate the GFR to be more accurate they will
substrat 10% from it because they don’t want the amount that being secreted by
the tubules , they want the amount that being filtered at the glomerulus.
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74. •Recall in MSK block the creatine will be converted to creatinine by losing H2O
and creatine phosphate will be converted to creatinine by removing phosphate
group , or as we know the pathway reversible so the creatine phosphate can be
converted to creatine and then will be converted to creatinine , this whole path
doesn’t need enzymes and this makes creatinine in kidney tests highly specific as
there are no enzymes that can be detected
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75. Creatinine clearance (CrCl)
•Clearance is the volume of plasma cleared from the
substance excreted in urine per minute.
- Creatinine clearance measures how well creatinine is
removed from your blood by your kidneys. The test is on a
sample of urine collected over 24 hours.
- It could be calculated from the following equation:
•You should know the limitation of this equation which is the
the volume of urine because maybe there will be some
mistakes during collecting the urine.
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77. Cockroft-gault formula for estimation of GFR
•As indicated in the previous slide , the creatinine clearance is
measured by using a 24-hour urine collection, but this does introduce
the potential for errors in terms of completion of the collection.
•The doctor will ask the patient to collect his/her urine during 24
hours and the doctor will calculate it by using the formula in the
previous slide but this way is not accurate due to some mistakes
during collecting the urine ,for instance maybe the patient will put
some of the water on the urine sample.
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78. •An alternative and convenient method is to employ various formulae
devised to calculate creatinine clearance using parameters such as
serum creatinine level, sex, age, and weight of the subject.
•Because measurement of creatinine clearance was not that accurate
they tried to use another way which is better than measuring the
creatinine clearance but unfortunately this way also has some
limitations.
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Where K is a constant that varies with sex:
1.23 for male & 1.04 for females.
The constant K is used as females have a
relatively lower muscle mass.
When we measure it in old machines it will be in
mg/dl so we have to convert it to µmol/L. How to
convert it ? By the conversation factor
The conversion factor is ( 88.4 )
1 mg/dl = 88.4 µmol/l
e.g : 2 mg/dl x 88.4 µmol/L = 176.8 µmol/L
another e.g : 176.8 µmol/L ÷ 88.4 µmol/L = 2
mg/dl

80. •The formula above is good because we excluded urine and replace
it with easier parameters.
•It should NOT be used if : ( the limitations for this formula )
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As we see on the formula the body weight is directly
proportional to the GFR so if the patient has high body weight
the GFR will be high which will be normal for him but if the
GFR in the normal range for a patient has a high body weight
this will indicate that there’s a problem in his renal function .
lack of proteins will decrease the
muscle mass.

81. •Creatinine clearance is only recommended in the following
conditions :
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83. Serum urea
(2.5 - 6.6 mmol/L) in adults
•Serum urea measures the amount of urea in the blood.
Urea is a waste product (non-toxic metabolite) made when
the protein is broken down in the body so it’s affected by
diet.
•Formation of urea in the liver.

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84. •As a kidney function test, serum urea is inferior to serum creatinine
because:
Any condition of increased proteins catabolism (Cushing syndrome,
diabetes mellitus, starvation, thyrotoxicosis) increases urea formation.
High protein diet increases urea formation.
50 % or more of urea filtered at the glomerulus is passively
reabsorbed by the renal tubules.
Dehydration can increase urea
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86. Examples of other kidney functions tests (KFTs):
Cystatin (C)
Microalbumin
β2- Microalbumin (11,800 Da)
Myoglobin (16,900 Da)

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87. Quiz
Q1: What is the best kidney function test (KFT) to estimate kidney function (KF) ?
A ) serum creatinine B ) urea C ) creatinine clearance D ) inulin
Q2: Which one is a limiting factor of the measurement of creatinine clearance ?
A ) urine volume B ) obesity C ) restrict Salts D ) the exercise
Q3: Which substance is used to diagnose early kidney disease ?
A ) serum creatinine B ) creatinine clearance C ) urea D ) none
Q4: What is the the substance that remains constant throughout adult life ?
A ) inulin B ) urea C ) creatine D ) creatinine
Q5: What is the site of urea formation ?
A ) stomach B ) kidney C ) liver D ) none
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