NON-PROTEIN NITROGEN (NPN) COMPOUNDS

Low molecular weight compounds that contain nitrogen and are distinguished from proteins based on their molecular size

NON-PROTEIN NITROGEN (NPN) COMPOUNDS

Analytes in the body that contains nitrogen that is not part of proteins

NON-PROTEIN NITROGEN (NPN) COMPOUNDS

Metabolic by-products is found in?

Urine

Blood

In animal ??, NPN are converted to proteins by bacteria in the ruminant stomach

animal nutrition

In animal nutrition, NPN are converted to proteins by ?? in the ruminant stomach

bacteria

In animal ???, they are incorporated to increase crude protein values which are measured based on N-content

feeds

In animal feeds, they are incorporated to increase ???? which are measured based on N-content

crude protein values

Animal feeds: Crude Protein Values

Protein: ???% N

16% N

Animal feeds: Crude Protein Values

Urea: ????% N

Urea: 47% N

Animal feeds: Crude Protein Values

Melamine: ???% N

Melamine: 66% N

Plasma Concentration (%)

Urea

45%

Plasma Concentration (%)

Amino acids

20%

Plasma Concentration (%)

Uric acids

20%

Plasma Concentration (%)

Creatinine

5%

Plasma Concentration (%)

Creatine

1-2%

Plasma Concentration (%)

Ammonia

0-2%

Lowest Plasma Concentration

Ammonia 0-2%

Highest Plasma Concentration

Urea 45%

Highest concentration of NPN in Blood (Major NPN)

BLOOD UREA NITROGEN

UREA NITROGEN (BUN) Concentration

40-45%

BUN Major excretory product of

oxidative protein AND amino acid metabolism

BLOOD UREA NITROGEN is synthesized in the ??? from CO2 and ammonia that arises from deamination of amino acids

liver

BLOOD UREA NITROGEN is synthesized in the liver from ?? and ?? that arises from deamination of amino acids

CO2 and ammonia

BLOOD UREA NITROGEN is synthesized in the liver from CO2 and ammoniathat arises from ??? of amino acids

deamination of amino acids

Synthesized in the liver from CO2 and ammonia that arises from deamination of amino acids

WHAT CYCLE

Urea Cycle (Kreb Cycle)

Ways BUN/Urea is produced

1. Protein/amino acid metabolism

2. Urea cycle/Kreb Cycle

Blood Urea concentration is determined by:

1. Renal function and perfusion

2. Dietary intake

3. Protein Catabolism Rate

Major site of excretion:

Kidney

Major site of excretion through the formation of

Through urine formation

first metabolite to increase in kidney disease

BUN

End product of protein

BUN

Upon synthesis, urea is carried to the ?? for excretion

Kidneys and GIT

High intake of protein = ???

high urea formation

Good indicator of state of hydration

Properly hydrated, normal BUN level

How fast the body can catabolize or breakdown protein

Protein Catabolism rate

Good indication of nitrogen intake

Protein Catabolism rate

has been used to refer to urea measurement

BUN

FORMULA for ACTUAL UREA

BUN x 2.14(mg/dL)

This is used if only the UREA value is needed

ACTUAL UREA = BUN x 2.14(mg/dL)

Conversion (mg/dL -> mmol/L)

- Actual urea (mg/dL) x 0.357 = Actual urea in mmol/L

- mg/dL x 0.36 (rounded off) = mmol/L

The most common method couples the urease reaction with glutamate dehydrogenase

ENZYMATIC (INDIRECT METHOD)

Enzyme used in ENZYMATIC (INDIRECT METHOD)

urease

End product of urease reaction:

glutamate and NAD+

Amount of NAD produced after the enzymatic reaction is measured

ENZYMATIC (INDIRECT METHOD)

Amount of NAD corresponds to the amount of

Urea (directly proportional)

NH4 (ammonium) + pH indicator =

color change

added to enhance color development to properly see the color changes in the said concentration of the urea

Thiosemicarbazide and Ferric ions

ENZYMATIC INDIRECT METHOD: The ?? after the reaction corresponds to the amount of urea

intensity of the color

Measure by the amount of electricity or conductivity it produces

CONDUCTRIMETRIC

Principle: Ammonium ion, when mixed with bicarbonate, produces a certain amount of conductivity

CONDUCTRIMETRIC

What is mixed in CONDUCTRIMETRIC

Ammonium ion and bicarbonate

An increasing conductivity corresponds to a ?? urea concentration

higher

Measures the production of indophenol blue when 2-phenol is added as the reagent

BERTHELOT RXN

reagent used in BERTHELOT RXN

2-phenol

production of indophenol blue measured by

BERTHELOT RXN

Most commonly used under the direct method

DIACTEYL MONOXIME (DAM)

added as the main reagent to produce diazine which appears as a yellow color compound after each reaction

Diacetyl

DAM: Diazine appears ?color? per each reaction

yellow

Diacetyl is added as the main reagent to produce ?

diazine

Principle of DIACTEYL MONOXIME (DAM)

Fearon’s Reaction

When o-pthaldehyde is added to the sample, ??? is produced as the end product

isoindoline

Directly measure urea with the addition of chemicals

CHEMICAL METHODS (DIRECT METHOD)

Reference method for in urea measurement

ISOTOPE DILUTION MASS SPECTROMETRY (IDMS)

Isotome Dilution Mass Spectrometry

Specimen Requirements

Serum, plasma, urine

Isotome Dilution Mass Spectrometry

Avoid additives such as

fluoride,

citrate,

ammonia

inhibits urease and can cause a falsely low value = false decrease

○ Fluoride and citrate i

causes contamination and can cause a falsely elevated value = false increase

Ammonia

Fasting reqirement

Non-fasting

Serum REFERENCE VALUES

6-20 mg/dL (0.36 → mmol/L)

Urine (24 hrs) REFERENCE VALUES

12-20g/day

An abnormally increased NPN (the entire NPN, not only urea) in the blood

azotemia

3 types of azotemia

Pre-renal:

Renal

Post-renal

Reduced Renal Blood Flow

→ less blood → less urea filtered

Pre-renal:

decreased/abnormal renal function → increased blood urea due

to poor excretion

Renal

If the origin of the disease comes from other organs except the kidney,

pre-renal condition.

Main cause of pre-renal condition is problems existing in the ? specifically a metal reduced renal blood flow.

blood

Main cause of pre-renal condition is problems existing in the blood, specifically a ?? reduced renal blood flow.

metal

Accumulation of NPN in the blood (urea cannot properly enter in the kidneys)

Pre-renal

Decreased renal perfusion

Pre-renal

DEHYDRATION (most common)

Shock

Congestive Heart Failure

Pre-renal

Decreased GFR with normal Renal Perfusion (RF)

Pre-renal

decreased/abnormal renal function → increased blood urea due to poor excretion

Renal

Decreased renal function

(damaged kidneys)

Renal

Glomerulonephritis

Renal

Acute and chronic kidney

diseases

Renal

Complications:

○ Coma

○ Neuropsychiatric changes

Renal

Value associated with renal condition

Urea nitrogen

> 100 mg/dL

Value associated with renal condition

creatinine

> 20 mg/dL

Value associated with renal condition

uric acid

> 12 mg/dL

mainly occurs as obstruction of urine flow

Post-Renal

Urinary tract damage

Post-Renal

Obstruction

Post-Renal

Back-diffusion of urea into

the blood

Post-Renal

Causes:

○ Renal calculi (kidney stones)

○ Cancer or tumors of GIT

Post-Renal

urine - high or low concentration of waste

high

Kidneys fail to eliminate waste products

UREMIA

Anemia

uremic frost (dirty skin/metal-like

color)

urine-like sweat

foul breath

UREMIA

Increased or Decreased Urea Nitrogen

- Fever

- Stress

Increased Urea Nitrogen

Increased or Decreased Urea Nitrogen

- Burns

- High protein intake

Increased Urea Nitrogen

Increased or Decreased Urea Nitrogen

- Dehydration

Increased Urea Nitrogen