The document discusses non-protein nitrogen (NPN) substances measured in clinical chemistry to evaluate renal function. It focuses on blood urea nitrogen (BUN), creatinine, uric acid, and ammonia. BUN, creatinine, and uric acid are produced from protein or nucleic acid breakdown, while ammonia is produced from amino acid metabolism. Increased levels of these NPNs can indicate renal or hepatic impairment. Creatinine is the most useful marker for glomerular filtration rate and renal function since it is not reabsorbed and its production rate is constant.
This chapter is largely about the water and electrolytes ( salts )in your plasma and how the body manages to keep you from drying up and blowing away even if you are in the hot Texas sun and without liquid drink.
This chapter is largely about the water and electrolytes ( salts )in your plasma and how the body manages to keep you from drying up and blowing away even if you are in the hot Texas sun and without liquid drink.
these clearance test plays an very important role in determining the functioning capacity and working status of kidney.
and we estimate how amount of compund is excreted in the urine and absorption too.
and i also attached the mathematical caluculation to identify the metabolic valuve of urea, creatinine, inulin clearance by kidney.
Estimation of Blood Urea Nitrogen by Dr. TehmasTehmas Ahmad
Lecture/Demonstration of Biochemistry Practical of Blood Urea Nitrogen estimation in serum Delivered on 11-04-2018 to 2nd year MBBS students of Bannu Medical College, Bannu.
Lipids are fatty substances that play an important role in a number of body functions. Apart from being structural components of the cells, Lipids also act as a source and mode of storage of energy for the body. The Lipid Profile Test measures the levels of specific types of lipids in the blood.
For more details, visit:
https://www.1mg.com/labs/test/lipid-profile-1909
This slide briefly imparts the knowledge of Amylase and Lipase enzymes. The clinical importance, calculation, concentration, sources and principle of amylase estimation are the major components of uploaded slide.
KFT are used for evaluating kidney functions. there are several routine tests such as urea, creatinine and uric acid. Calculation of eGFR is recommended by national kidney organization whenever creatinine serum is measured.
Renal function tests are very useful for effective clinical evaluation of renal failure for effective management. So it is useful for medical and allied professional students and clinical practitioners.
Test for pancreatic and intestinal functions are very important for clinical evaluation gastro intestinal disorders . So it will e useful for medical and allied professional students and practitioners.
these clearance test plays an very important role in determining the functioning capacity and working status of kidney.
and we estimate how amount of compund is excreted in the urine and absorption too.
and i also attached the mathematical caluculation to identify the metabolic valuve of urea, creatinine, inulin clearance by kidney.
Estimation of Blood Urea Nitrogen by Dr. TehmasTehmas Ahmad
Lecture/Demonstration of Biochemistry Practical of Blood Urea Nitrogen estimation in serum Delivered on 11-04-2018 to 2nd year MBBS students of Bannu Medical College, Bannu.
Lipids are fatty substances that play an important role in a number of body functions. Apart from being structural components of the cells, Lipids also act as a source and mode of storage of energy for the body. The Lipid Profile Test measures the levels of specific types of lipids in the blood.
For more details, visit:
https://www.1mg.com/labs/test/lipid-profile-1909
This slide briefly imparts the knowledge of Amylase and Lipase enzymes. The clinical importance, calculation, concentration, sources and principle of amylase estimation are the major components of uploaded slide.
KFT are used for evaluating kidney functions. there are several routine tests such as urea, creatinine and uric acid. Calculation of eGFR is recommended by national kidney organization whenever creatinine serum is measured.
Renal function tests are very useful for effective clinical evaluation of renal failure for effective management. So it is useful for medical and allied professional students and clinical practitioners.
Test for pancreatic and intestinal functions are very important for clinical evaluation gastro intestinal disorders . So it will e useful for medical and allied professional students and practitioners.
Renal function test (RFT), also known as kidney function test is a group of tests used to assess the functions of kidney.
It is used screen for, detect, evaluate and monitor acute and chronic kidney diseases.
These are simple blood and urine tests that are used identify kidneys problems.
Tests of renal function have utility in-
Identifying the presence of renal disease
Monitoring the response of kidneys to treatment
Determining the progression of renal disease
RFT is ordered, if your doctor
thinks your kidneys may not be working properly which is known from signs and symptoms
and if you have other conditions that can harm the kidneys, such as diabetes or high blood pressure
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This presentation by Morris Kleiner (University of Minnesota), was made during the discussion “Competition and Regulation in Professions and Occupations” held at the Working Party No. 2 on Competition and Regulation on 10 June 2024. More papers and presentations on the topic can be found out at oe.cd/crps.
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Supercharge your AI - SSP Industry Breakout Session 2024-v2_1.pdf
Non protein nitrogen
1. 1
CLINICAL CHEMISTRY
NON - PROTEIN NITROGEN
Presented by: Shahid Nawaz
Researcher
King Saud University
Riyadh
2. 2
Introduction
• NPN ( Non - Protein Nitrogen ) is a “funky” term that can be used for
a bunch of different substances that have the element nitrogen in them,
but are not proteins.
• This is a little unusual, because most of the body’s nitrogen is
associated with proteins.
• There are many different unrelated NPNs, but we are only interested in
4 of them:
• Creatinine , Blood Urea Nitrogen ( BUN ) , Uric Acid and Ammonia
• In general, plasma NPNs are increased in renal failure and are
commonly ordered as blood tests to check renal function
4. 4
Objectives
• List the origin and principle clinical significance of BUN, Creatinine,
Uric Acid and Ammonia
• List the reference ranges for the 4 principle NPNs
• Discuss why creatinine is the most useful NPN to evaluate renal
function
• Calculate Creatinine Clearance
• Discuss the common methodologies used to measure BUN, Creatinine,
Uric Acid and Ammonia
5. 5
• General ideas about the NPNs
• Antiquated term when protein – free filtrates were required for testing
• The NPNs were used for evaluating renal function
• The NPNs include about 15 different substances
• Most NPNs are derived from protein or nucleic acid catabolism
• Most important NPNs
– BUN ( Blood Urea Nitrogen )
– Creatinine
– Uric acid
– Ammonia
6. 6
• BUN ( Blood Urea Nitrogen )BUN ( Blood Urea Nitrogen )
– Blood Urea Nitrogen = BUNBUN = Urea
– 50% of the NPNs
– Product of protein catabolism which produces ammonia
– Ammonia is very toxic – converted to urea by the liver
– Liver converts ammonia and CO2
– Filtered by the glomerulus but also reabsorbed by renal tubules ( 40 % )
– Some is lost through the skin and the GI tract ( < 10 % )
– Plasma BUN is affected by
• Renal function
• Dietary protein
• Protein catabolism
Urea
7. 7
– BUN disease correlationsBUN disease correlations
• Azotemia = Elevated plasma BUN
• PrerenalPrerenal ↑↑ BUNBUN ( Not related to renal function )
– Low Blood Pressure ( CHF, Shock, hemorrhage, dehydration )
– Decreased blood flow to kidney = No filtration
– Increased dietary protein or protein catabolism
• PrerenalPrerenal ↓↓ BUNBUN ( Not related to renal function )
– Decreased dietary protein
– Increased protein synthesis ( Pregnant women , children )
8. 8
– RenalRenal causes ofcauses of ↑↑ BUNBUN
• Renal disease with decreased glomerular filtration
– Glomerular nephritis
– Renal failure form Diabetes Mellitus
– Post renalPost renal causes ofcauses of ↑↑ BUN ( not related to renal function )BUN ( not related to renal function )
• Obstruction of urine flow
– Kidney stones
– Bladder or prostate tumors
– UTIs
9. 9
• BUN / Creatinine RatioBUN / Creatinine Ratio
– Normal BUN / Creatinine ratio is 10 – 20 to 1Normal BUN / Creatinine ratio is 10 – 20 to 1
– Creatinine is another NPNCreatinine is another NPN
– Pre-renal increased BUN / Creat ratio
– BUN is more susceptible to non-renal factors
– Post-renalPost-renal increased ratio BUN / Creat ratio
– Both BUN and Creat are elevated
– RenalRenal decreased BUN / Creat ratio
– Low dietary protein or severe liver disease
Increased BUN
Normal Creat
Increased BUN
Increased Creat
Decreased BUN
Normal Creat
10. 10
– BUN analytical methodsBUN analytical methods
• BUN is an old term, but still in common useBUN is an old term, but still in common use
• Specimen : Plasma or serum
• To convert BUN to Urea : BUN x 2.14 = Urea ( mg / dl )
UREA 2 NH4
+
+ HCO3
-
Urease
NH4
+
+ 2-OXOGLUTARATE
GLDH
GLUTAMATE
NADH NAD
Measure the rate of decreased absorbance at 340 nm
NADH absorbs … NAD does not absorb
Reference range : 10 – 20 mg / dl
11. 11
• CREATININE
Liver Amino Acids Creatine
Muscles Creatine Phosphocreatine
Muscles Phosphocreatine Creatinine
Creatinine formed at a constant rate by the muscles as a function of muscle mass
Creatinine is removed from the plasma by glomerular filtration
Creatinine is not secreted or absorbed by the renal tubules
Therefore : Plasma creatinine is a function of glomerular filtration
Unaffected by other factors
It’s a very good test to evaluate renal function
12. 12
– Creatinine disease correlations
• Increased plasma creatinine associated with decreased
glomerular filtration ( renal function )
• Glomerular filtration may be 50 % of normal before plasma
creatinine is elevated
• Plasma creatinine is unaffected by diet
• Plasma creatinine is the most common test used to evaluate
renal function
• Plasma creatinine concentrations are very stable from day to
day - If there is a delta check , its very suspicious and must be
investigated
14. 14
• URIC ACID
– Breakdown product of purines ( nucleic acid / DNA )
– Purines from cellular breakdown are converted to uric acid by the
liver
– Uric acid is filtered by the glomerulus ( but 98 – 100 % reabsorbed )
– Elevated plasma uric acid can promote formation of solid uric acid
crystals in joints and urine
15. 15
– Uric acid diseases
• Gout
– Increased plasma uric acid
– Painful uric acid crystals in joints
– Usually in older males ( > 30 years-old )
– Associated with alcohol consumption
– Uric acid may also form kidney stones
• Other causes of increased uric acid
– Leukemias and lymphomas ( ↑ DNA catabolism )
– Megaloblastic anemias ( ↑ DNA catabolism )
– Renal disease ( but not very specific )
16. 16
– Uric acid analysis
Uric acid + O2 + H2O Allantoin + CO2
Uricase
Uric acid absorbs light @ 293 nm , Allantoin does not.
The rate of decreased absorption is proportional to the uric acid
concentration.
Specimen : Plasma or serum
+ H2O2
Reference range : 3.5 - 7.2 mg/dl (males)
2.6 - 6.0 mg/dl (females)
Let’s remember 3.0 - 7.0 mg/dl
17. 17
• AMMONIA
– Produced from the deamaination of amino acids in the muscle and
from bacteria in the GI tract
– Ammonia is very toxic - The liver converts ammonia into urea
– Urea is less toxic and can be removed from the plasma by the
kidneys
– In severe hepatic disease, the liver fails to convert ammonia into
urea, resulting in increased plasma ammonia levels
– Increased plasma ammonia concentrations in :
• Liver failure
• Reye’s Disease
18. 18
Ammonia analytical techniques
NH4
+
+ 2-OXOGLUTARATE + NADPH L-GLUTAMATE +
NADP+
There is a decreasing absorbance @ 340 nm, proportional to the
ammonia concentration.
Specimen : EDTA or Heparinized Whole Blood on ice
Must be tested ASAP or plasma frozen
Delayed testing caused false increased values
Reference range : 20 – 60 µg / dl
19. 19
• Creatinine Clearance
– Calculated measurement of the rate at which creatinine is removed from
the plasma by the kidneys
– Measurement of glomerular filtration ( renal function )Measurement of glomerular filtration ( renal function )
– A good test of glomerular filtration because
• Creatinine is an endogenous substance ( not affected by diet )
• Creatinine is filtered by the glomerulus, but not secreted or
re-absorbed by the renal tubules
20. 20
24 Hour Urine collection
Container.
The volume can be measured
directly off the container.
21. 21
– Creatinine Clearance specimens
• 24 hour urine specimen
• Plasma / serum creatinine collected during the urine collection
• 24 Hour Creatinine Clearance Formula
• CREATININE CLEARANCE =
A
U 73.1
P
V
U = Creatinine concentration of the 24 hour urine ( mg / dl )
V = 24 hour urine volume ( mls ) per minute - V / 1440 = mls / minuteper minute - V / 1440 = mls / minute
P = Plasma creatinine concentration ( mg / dl )
A = Correction factor accounts for differences in body surface area
obtained from a height – weight chart
22. 22
Example of a 24 Hour Creatinine Clearance calculation
24 hour urine volume = 1000 mls
24 hour urine creatinine = 20.0 mg / dl
Plasma creatinine = 5.0 mg / dl
Patients height / weight = 6’00 / 190 lbs ( see pg. 680 )
( )
( )
( ) ( )
( )
100020.01.73 1.731440
5.0 2.05
UV
Creat Cl
P A
= = = ÷ ÷
Creat Cl = 2 ml / min …. Very poor clearance !!!
23. 23
• Procedure for 24 Hour Urine Collection
– Have the patient empty his / her bladder ( discard this urine ).
– Note the time . For the next 24 hours, have the patient collect and save all
urine in an appropriate container.
– At the end of the 24 hour period have the patient void one last time into
the urine container. This completes the collection.
– If possible, keep the urine specimen refrigerated.
24. 24
– Reference range
• 97 - 137 ml / min ( male)
• 88 - 128 ml / min (female)
• Let’s remember 90 - 130 ml / min
25. 25
NPN TOP 10
• Increased Creatinine associated with renal failure
• Increased BUN associated with renal failure and protein catabolism
• Increased Uric Acid associated with Gout
• Increased Ammonia is associated with liver disease
• Creatinine derived from cellular creatine … very constant from day to day
• Delta checks on plasma Creatinine must be investigated !!!
• BUN ( Urea ) is derived from protein catabolism
• Protein Ammonia Urea
• Uric Acid is derived from purine( a component of DNA ) catabolism
• Decreased Creatinine Clearance associated with decreased Glomerular
Filtration
=
AP
UV 73.1
ClearanceCreatinine
Don’t forget to divide V by 1440 !
26. 26
Reference Ranges
• BUN 10 - 20 mg / dl
• Creatinine 0.5 - 1.5 mg /dl
• Uric Acid 3.0 - 7.0 mg / dl
• Creatinine Clearance 90 - 130 ml / min
• Ammonia 20 - 60 ug / dl
• BUN / Creat Ratio 10 - 20 to 1