PBBSC FY UNIT 5 BIOCHEMISTRY.

🧬 AMINO ACIDS: Structure, Classification, Functions, and Clinical Significance

🔹 Definition

Amino acids are organic compounds that serve as the building blocks of proteins. They contain two main functional groups:

Amino group (-NH₂)
Carboxyl group (-COOH)
Attached to a central carbon (α-carbon), along with a hydrogen atom and a unique side chain (R-group).

🔹 Classification of Amino Acids

1. Based on Nutritional Requirement

Essential Amino Acids: Cannot be synthesized by the body (must be taken in diet)
- Examples: Leucine, Isoleucine, Valine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Histidine
Non-Essential Amino Acids: Can be synthesized by the body
- Examples: Alanine, Glutamate, Aspartate, Serine
Conditionally Essential: Required in illness or stress
- Example: Arginine, Glutamine

2. Based on Polarity

Non-polar (Hydrophobic): Glycine, Alanine, Valine
Polar (Hydrophilic): Serine, Threonine, Cysteine
Charged:
- Acidic: Aspartate, Glutamate
- Basic: Lysine, Arginine, Histidine

🔹 Functions of Amino Acids

Protein synthesis
Precursor for hormones, neurotransmitters (e.g., tryptophan → serotonin)
Immune function (e.g., glutamine)
Wound healing (arginine)
Energy production during fasting/starvation

🔹 Clinical Relevance in Nursing

Phenylketonuria (PKU): Deficiency of enzyme to metabolize phenylalanine → intellectual disability
Maple Syrup Urine Disease: Defect in metabolism of branched-chain amino acids
Protein-energy malnutrition: Deficiency of essential amino acids
Burns or Sepsis: Increased need for glutamine and arginine

🔬 HORMONES: Types, Functions, Regulation, and Nursing Relevance

🔹 Definition

Hormones are chemical messengers secreted by endocrine glands into the bloodstream, affecting target organs to regulate physiology and behavior.

🔹 Types of Hormones (Based on Chemical Nature)

Peptide/Protein Hormones
- Examples: Insulin, Glucagon, ADH, Oxytocin
- Water-soluble, bind to membrane receptors
Steroid Hormones
- Examples: Cortisol, Aldosterone, Estrogen, Testosterone
- Fat-soluble, derived from cholesterol, act on intracellular receptors
Amine Hormones
- Derived from amino acids (e.g., tyrosine)
- Examples: Epinephrine, Norepinephrine, Thyroxine (T4), Triiodothyronine (T3)

🔹 Major Endocrine Glands and Their Hormones

Gland	Hormone(s)	Function(s)
Pituitary	GH, ACTH, TSH, LH, FSH	Growth, adrenal & thyroid stimulation, reproductive control
Thyroid	T3, T4, Calcitonin	Metabolism regulation, calcium balance
Parathyroid	PTH	Calcium and phosphate balance
Adrenal	Cortisol, Aldosterone, Adrenaline	Stress response, BP regulation, fight-or-flight
Pancreas	Insulin, Glucagon	Blood glucose control
Ovaries	Estrogen, Progesterone	Female reproductive cycle and pregnancy
Testes	Testosterone	Male secondary sexual characteristics

🔹 Nursing Implications of Hormonal Disorders

Hormone Imbalance	Condition	Symptoms	Nursing Considerations
↓ Insulin	Diabetes Mellitus	Polyuria, polydipsia, fatigue	Monitor blood sugar, insulin therapy
↓ Thyroxine	Hypothyroidism	Weight gain, lethargy, cold intolerance	Levothyroxine, monitor TSH levels
↑ Cortisol	Cushing’s Syndrome	Moon face, truncal obesity, hypertension	Medication, surgery, cortisol monitoring
↓ ADH	Diabetes Insipidus	Excessive urination, dehydration	Monitor I/O, administer desmopressin
↑ PTH	Hyperparathyroidism	Bone pain, kidney stones	Hydration, monitor calcium levels

🧪 BIOCHEMISTRY IN NURSING

🔹 Importance of Biochemistry for Nurses

Understand drug metabolism and action
Interpret lab values (e.g., electrolytes, enzymes, hormones)
Manage IV fluids, acid-base imbalances, nutrition
Detect metabolic disorders (e.g., DKA, uremia)
Plan dietary care (especially for renal, liver, diabetic, and cancer patients)

🔹 Core Topics of Biochemistry for Nursing

Topic	Clinical Importance in Nursing
Carbohydrate Metabolism	Blood glucose regulation, diabetes management
Lipid Metabolism	Cholesterol control, cardiovascular risk monitoring
Protein Metabolism	Wound healing, burns, malnutrition
Enzymes	Liver function (ALT, AST), cardiac markers (CK-MB, Troponin)
Electrolytes	Fluid/electrolyte balance (Na⁺, K⁺, Ca²⁺), especially in cardiac and renal care
Acid-Base Balance	ABG analysis, respiratory/metabolic acidosis or alkalosis
Vitamins and Cofactors	Deficiency disorders (e.g., rickets, scurvy, anemia)
Nucleic Acids & DNA	Basics of genetics, mutations, and implications in genetic diseases
Clinical Biochemistry Tests	Liver, kidney, thyroid function tests; lipid profile; glucose levels

✅ Summary – Key Points for Nursing Practice

Understand basic structures and functions of amino acids and hormones to apply in clinical scenarios.
Monitor hormone levels and their physiological effects for diagnosing endocrine disorders.
Interpret biochemical lab reports for planning care in diabetes, liver/kidney diseases, and malnutrition.
Educate patients on nutrition, lifestyle, and medication related to metabolic and hormonal disorders.

🧬 Essential Amino Acids:

🔹 Definition

Essential amino acids are amino acids required for protein synthesis but cannot be synthesized by the human body in sufficient amounts. Therefore, they must be obtained through the diet.

These amino acids are vital for growth, tissue repair, enzyme and hormone production, immune function, and overall metabolism.

🔹 List of 9 Essential Amino Acids

No.	Amino Acid	Unique Role/Function
1.	Histidine	Growth, tissue repair, RBC & WBC production
2.	Isoleucine	Muscle metabolism, energy, hemoglobin formation
3.	Leucine	Muscle repair, insulin regulation, wound healing
4.	Lysine	Calcium absorption, immune support, collagen
5.	Methionine	Detoxification, antioxidant (glutathione synthesis)
6.	Phenylalanine	Precursor of neurotransmitters (dopamine, norepinephrine)
7.	Threonine	Collagen, tooth enamel, immune support
8.	Tryptophan	Precursor of serotonin, melatonin (sleep, mood)
9.	Valine	Muscle growth, energy production, stress recovery

🔹 Mnemonic for Easy Recall

📚 PVT TIM HALL
Phenylalanine
Valine
Tryptophan
Threonine
Isoleucine
Methionine
Histidine
Arginine (semi-essential in children)
Leucine
Lysine

🧒 Note: Arginine is essential only during growth phases (children, pregnancy, illness).

🔹 Functions of Essential Amino Acids

Amino Acid	Specific Functions
Histidine	Maintains myelin sheaths, produces histamine (immune/allergy response)
Isoleucine	Supports muscle recovery, energy for muscles, regulates blood sugar
Leucine	Stimulates muscle protein synthesis, healing tissues, regulates blood sugar
Lysine	Collagen and elastin synthesis, aids in calcium absorption and antiviral actions
Methionine	Detoxifies harmful substances, supports liver function, maintains healthy skin
Phenylalanine	Forms tyrosine → dopamine, epinephrine, norepinephrine; supports mental health
Threonine	Supports heart, liver, CNS, immune system; part of tooth enamel and collagen
Tryptophan	Converts to serotonin (mood, sleep), melatonin (circadian rhythm), niacin (B3)
Valine	Fuel for muscles, muscle regeneration, CNS stimulant

🔹 Dietary Sources of Essential Amino Acids

Food Source Type	Examples
Animal-Based	Eggs, meat, chicken, fish, milk, cheese, yogurt
Plant-Based	Soy products (tofu, soy milk), quinoa, legumes, nuts, seeds, whole grains

🌱 Most plant sources are incomplete proteins, lacking one or more essential amino acids, but combining foods (e.g., rice + beans) gives a complete amino acid profile.

🔹 Clinical Significance for Nurses

Deficiency	Symptoms	Common Conditions	Nursing Interventions
Lysine	Fatigue, anemia, poor wound healing	Vegan diets, malnutrition	Encourage lysine-rich foods
Tryptophan	Insomnia, depression, anxiety	Sleep disorders, mood disorders	Promote tryptophan-rich diet
Methionine	Liver problems, skin disorders	Liver cirrhosis, fatigue	Supplementation if needed
Threonine	Poor immunity, fatty liver	Chronic illness	Monitor nutritional intake
Leucine/Valine/Isoleucine	Muscle loss, weakness	Burn injuries, trauma	High-protein supplementation

🔹 Role in Nursing and Patient Care

Wound Healing: Leucine and lysine support tissue repair and collagen formation
Mental Health: Tryptophan and phenylalanine affect neurotransmitter balance
Growth Monitoring: Essential amino acids are critical in pediatrics and neonates
Surgical Recovery: Post-operative patients need adequate protein including essential amino acids
Elderly and Chronically Ill: Risk of protein-energy malnutrition, requiring dietary planning
Enteral/Parenteral Nutrition: Nurses must assess complete protein needs in patients on tube feeds or TPN

✅ Summary

There are 9 essential amino acids that must be obtained through diet.
They are critical for growth, repair, immunity, hormone production, and neurotransmitter synthesis.
Deficiency can cause growth failure, muscle loss, poor immunity, and mental disturbances.
Nurses play a key role in assessing dietary intake, educating patients, and preventing complications from amino acid deficiencies.

🧬 Protein Biosynthesis in Cells (Protein Synthesis)

🔹 Definition

Protein biosynthesis is the multi-step process by which cells build proteins using the genetic code stored in DNA. This process is vital for cell structure, enzyme production, hormones, antibodies, repair, and growth.

📍 It occurs in two main stages:

Transcription – in the nucleus
Translation – in the cytoplasm (at ribosomes)

🔄 Overview of the Process

DNA → mRNA → Protein

🧾 STAGE 1: TRANSCRIPTION (In Nucleus)

Purpose: To make a messenger RNA (mRNA) copy of the DNA gene.

🔹 Steps:

Initiation:
- An enzyme called RNA polymerase binds to a promoter region of the DNA.
- The DNA double helix unwinds to expose a single strand.
Elongation:
- RNA polymerase reads the DNA template strand and adds complementary RNA nucleotides (A, U, C, G).
- Uracil (U) replaces thymine (T) in RNA.
Termination:
- When a stop signal is reached, RNA polymerase detaches.
- A pre-mRNA strand is released.
mRNA Processing (in eukaryotes):
- Introns (non-coding regions) are removed, and exons are spliced together.
- A cap and poly-A tail are added to stabilize the mRNA.

✅ Result: A mature mRNA strand leaves the nucleus and travels to the cytoplasm.

🧾 STAGE 2: TRANSLATION (In Cytoplasm at Ribosomes)

Purpose: To translate the mRNA sequence into a specific amino acid chain (protein).

🔹 Components Involved:

mRNA – Carries the genetic code
tRNA (Transfer RNA) – Brings amino acids
Ribosome – Reads mRNA and forms peptide bonds
Amino acids – Building blocks of proteins

🔹 Steps:

Initiation:
- The ribosome attaches to the start codon (AUG) on mRNA.
- A tRNA carrying methionine pairs with the start codon.
Elongation:
- tRNAs bring specific amino acids to the ribosome.
- Each tRNA has an anticodon that matches the mRNA codon.
- The ribosome joins amino acids with peptide bonds forming a polypeptide chain.
Termination:
- When a stop codon (UAA, UAG, UGA) is reached, translation stops.
- The polypeptide is released and folds into a functional protein.

✅ Result: A newly synthesized protein is formed, ready for transport or function.

🧪 Clinical Relevance in Nursing

Relevance	Example / Implication
Genetic disorders	Sickle cell anemia (mutation in the DNA affecting protein made)
Antibiotics action	Some antibiotics (like tetracycline) block bacterial protein synthesis
Cancer treatment	Some chemotherapy drugs target protein synthesis in rapidly dividing cells
Malnutrition	Lack of essential amino acids impairs protein synthesis
Wound healing	Protein synthesis is crucial for tissue repair
Hormone production	Many hormones (e.g., insulin) are proteins
Enzyme deficiencies	Inherited enzyme disorders affect protein function

🧠 Quick Terms for Revision

Term	Meaning
Codon	A 3-letter sequence on mRNA coding for one amino acid
Anticodon	Complementary 3-letter sequence on tRNA
tRNA	Transfer RNA, brings amino acids to the ribosome
mRNA	Messenger RNA, copy of DNA’s code
rRNA	Ribosomal RNA, structural part of ribosome
Peptide bond	Link between two amino acids

🧠 Mnemonic for Protein Synthesis Stages

🧬 “Transcribe In Nucleus, Translate In Cytoplasm”

Transcription = Nucleus
Translation = Cytoplasm

✅ Summary – Key Points for Nurses

Protein synthesis is essential for growth, repair, enzymes, hormones, and immunity.
DNA gives the instructions, mRNA carries it, ribosomes read it, and tRNA brings the building blocks.
Understanding this process helps in interpreting diseases like genetic disorders, metabolic diseases, and drug actions.
Nurses play a vital role in patient nutrition, as proteins and amino acids are critical to this process.

🧬 Role of Nucleic Acids in Protein Synthesis

🔹 Definition of Nucleic Acids

Nucleic acids are biological macromolecules that store and transmit genetic information. The two main types are:

DNA (Deoxyribonucleic Acid)
RNA (Ribonucleic Acid)

These molecules direct and control the synthesis of proteins, which are essential for the structure and function of every cell.

🔄 Overview of Protein Synthesis Involving Nucleic Acids

DNA → mRNA → Protein

This process occurs in two major stages:

Transcription (in the nucleus)
Translation (in the cytoplasm)

🧾 1. DNA: The Genetic Blueprint

🔹 Role in Protein Synthesis:

DNA contains genes, which are specific sequences of nucleotides coding for proteins.
A gene is transcribed into mRNA to begin protein synthesis.

🔹 Structure and Function:

Made of nucleotides (Adenine, Thymine, Cytosine, Guanine)
Double-stranded helix
Base pairing: A-T, C-G

🧠 Nursing Relevance: Mutations or damage in DNA can lead to genetic disorders or cancer (e.g., BRCA gene mutations in breast cancer).

🧾 2. RNA: The Functional Worker

There are three main types of RNA, each playing a crucial role in protein synthesis:

🟠 A. Messenger RNA (mRNA)

Function: Carries genetic code from DNA to ribosomes
Created by transcription of DNA in the nucleus
Contains codons – sequences of 3 bases coding for an amino acid
Travels from the nucleus to the cytoplasm

🧠 Nursing Tip: mRNA is the target of some vaccines (like mRNA COVID-19 vaccines), which teach the body to make viral proteins and generate immunity.

🟠 B. Transfer RNA (tRNA)

Function: Transfers specific amino acids to the ribosome
Each tRNA has an anticodon that pairs with the mRNA codon
Ensures the correct amino acid is added to the growing protein chain

🧠 Nursing Relevance: A lack of specific amino acids (malnutrition) impairs this process, affecting wound healing and immune function.

🟠 C. Ribosomal RNA (rRNA)

Function: Structural and functional part of ribosomes
rRNA helps read the mRNA and form peptide bonds between amino acids

🧠 Nursing Tip: Ribosomes are the sites of protein synthesis, and rRNA ensures accuracy in protein formation.

📊 Summary of Roles of Nucleic Acids

Nucleic Acid	Role in Protein Synthesis	Location
DNA	Stores genetic code; provides template for mRNA	Nucleus
mRNA	Copies genetic information; delivers it to ribosomes	Nucleus → Cytoplasm
tRNA	Brings amino acids to ribosome; matches codons with anticodons	Cytoplasm
rRNA	Forms ribosomes; catalyzes peptide bond formation	Cytoplasm

🔬 Clinical Applications for Nurses

Application	Clinical Relevance
Genetic testing	Identifies mutations in DNA (e.g., for inherited diseases, cancer risk)
RNA-based vaccines	mRNA vaccines teach the immune system to recognize pathogens
Protein synthesis inhibitors	Many antibiotics (e.g., tetracyclines, macrolides) block bacterial RNA function
Malnutrition effects	Without amino acids, even proper RNA function can’t make proteins

🧠 Key Takeaways

DNA provides the instructions; RNA carries out those instructions.
mRNA is like a photocopy of the gene.
tRNA is the delivery truck for amino acids.
rRNA is the factory machine building the protein.
All these work together to make proteins—vital for healing, enzymes, hormones, and immune defense.

🧬 Nitrogenous Constituents of Urine and Blood

🔹 Definition

Nitrogenous waste products are metabolic byproducts containing nitrogen, primarily derived from protein and nucleic acid metabolism. These are toxic if accumulated, so the body excretes them, mainly through urine and blood transport systems.

🚰 Nitrogenous Constituents in URINE

🔹 1. Urea

Origin: Breakdown of amino acids (protein catabolism) in the liver
Pathway: Amino acids → Ammonia (NH₃) → Converted to urea via the urea cycle (in liver)
Excretion: Filtered by kidneys and excreted in urine

🔍 Clinical Relevance:

Increased urea = Azotemia or Uremia → Seen in renal failure
Measured as BUN (Blood Urea Nitrogen) in blood tests

🔹 2. Creatinine

Origin: From creatine phosphate breakdown in muscle metabolism
Constant production, proportional to muscle mass
Excretion: Filtered by kidneys; minimal reabsorption

🔍 Clinical Relevance:

Elevated levels = Impaired kidney function
Used in GFR estimation (glomerular filtration rate)

🔹 3. Uric Acid

Origin: Metabolism of purines (adenine, guanine from DNA/RNA)
Excretion: Filtered by kidneys, some reabsorbed

🔍 Clinical Relevance:

High levels = Hyperuricemia, may lead to Gout
Seen in renal failure and tumor lysis syndrome

🔹 4. Ammonia

Origin: Deamination of amino acids
Normally converted to urea in the liver (urea cycle)
Small amounts excreted in urine to help maintain acid-base balance

🔍 Clinical Relevance:

↑ Ammonia = Hepatic failure or hepatic encephalopathy

🔹 5. Hippuric Acid

Origin: Detoxification of benzoic acid in the liver
Excretion: Urine

🔍 Mild increase in diet rich in fruits and vegetables

🔹 6. Indican

Origin: From tryptophan metabolism in the intestine
Absorbed into blood → liver → excreted in urine

🔍 Excess indican = intestinal putrefaction or constipation

🔹 7. Allantoin (minor in humans)

Origin: Uric acid oxidation (significant in some animals, minor in humans)

🩸 Nitrogenous Constituents in BLOOD

Constituent	Origin	Normal Value (approx.)	Clinical Significance
Urea (BUN)	Protein breakdown in liver	7–20 mg/dL	↑ in kidney failure, dehydration, GI bleeding
Creatinine	Muscle metabolism	0.6–1.2 mg/dL (adult)	↑ in renal impairment; ↓ in muscle wasting
Uric Acid	Purine breakdown	Male: 3.4–7.0 mg/dL; Female: 2.4–6.0 mg/dL	↑ in gout, leukemia, chemotherapy
Ammonia	Amino acid deamination	15–45 µg/dL	↑ in liver failure, Reye’s syndrome

🔬 Summary Table: Nitrogenous Waste – Origin & Route

Waste Product	Source / Origin	Organ Involved	Excreted By
Urea	Amino acids (proteins)	Liver	Kidneys (urine)
Creatinine	Muscle metabolism (creatine)	Muscle	Kidneys
Uric Acid	Purines (DNA/RNA)	Liver	Kidneys
Ammonia	Deamination of amino acids	Liver	Urine (small amt), exhaled (lungs)
Hippuric Acid	Benzoic acid detox	Liver	Kidneys
Indican	Intestinal tryptophan metabolism	Intestine/Liver	Kidneys

🧠 Nursing Implications

Condition	Nurse’s Role
Renal failure	Monitor BUN, creatinine; manage fluid and electrolyte balance
Hepatic failure	Monitor ammonia levels; administer lactulose
Gout	Diet advice (low purine), administer uric acid-lowering drugs
Dehydration	Can falsely elevate urea – ensure adequate hydration
High protein intake	Educate patients with kidney/liver disorders on moderation

✅ Key Takeaways

Nitrogenous waste products mainly come from protein and nucleic acid metabolism.
Urea is the most abundant nitrogenous compound in urine.
Creatinine and BUN are key markers of renal function.
Nurses should understand these values for interpreting lab reports, managing kidney/liver disorders, and educating patients on dietary management.

🧬 UREA CYCLE (ORNITHINE CYCLE)

🔹 Definition

The urea cycle is a biochemical process in the liver that converts toxic ammonia (produced from protein breakdown) into urea, which is non-toxic and can be excreted safely via the kidneys through urine.

✅ The urea cycle is essential for nitrogen excretion and maintaining a non-toxic internal environment.

📍 Why is the Urea Cycle Important?

Proteins → Amino acids → Ammonia (NH₃) (toxic)
Ammonia is highly toxic to cells, especially the brain.
The urea cycle detoxifies ammonia by converting it to urea in the liver.
Urea is then transported in the blood to the kidneys, where it is excreted in urine.

🏭 Location of the Urea Cycle

Takes place primarily in the liver
Partially occurs in the mitochondria and cytoplasm of liver cells (hepatocytes)

🔄 Steps of the Urea Cycle

🧾 Step-by-step Pathway:

Step	Location	Description
1.	Mitochondria	Ammonia (NH₃) + CO₂ → Carbamoyl phosphate (via enzyme CPS-I)
2.	Mitochondria	Carbamoyl phosphate + Ornithine → Citrulline (via ornithine transcarbamylase)
3.	Cytoplasm	Citrulline + Aspartate → Argininosuccinate (via argininosuccinate synthetase)
4.	Cytoplasm	Argininosuccinate → Arginine + Fumarate (via argininosuccinase)
5.	Cytoplasm	Arginine → Urea + Ornithine (via arginase) – cycle restarts with ornithine

✅ End products:

Urea → excreted in urine
Fumarate → enters the Krebs cycle
Ornithine → reused in the cycle

💡 Mnemonic for Enzymes Involved

“Can Our Aunt Ask For Urea?”

Carbamoyl phosphate synthetase I
Ornithine transcarbamylase
Argininosuccinate synthetase
Argininosuccinate lyase
Fumarate (byproduct)
Urea (final product)

⚠️ Clinical Relevance: Disorders of Urea Cycle

Disorder	Deficiency/Issue	Clinical Signs
Hyperammonemia	Excess ammonia due to cycle failure	Confusion, vomiting, coma, encephalopathy
Liver failure (cirrhosis)	Impaired urea cycle	↑ blood ammonia → hepatic encephalopathy
Urea Cycle Enzyme Deficiencies	Congenital (e.g., OTC deficiency)	Lethargy, seizures in neonates

🧠 Nursing Implication:

Monitor ammonia levels
Administer lactulose to reduce ammonia
Protein-restricted diet in urea cycle disorders
Educate patient on early signs of toxicity (especially in liver disease)

📊 Urea Cycle Summary Table

Molecule Involved	Function
Ammonia (NH₃)	Toxic waste from amino acid metabolism
Urea	Non-toxic form of nitrogen for excretion
Ornithine	Carrier molecule reused in the cycle
Citrulline	Intermediate in urea formation
Aspartate	Provides second nitrogen atom for urea
Fumarate	Links urea cycle to energy metabolism

✅ Nursing Takeaways

Urea cycle helps eliminate nitrogen waste safely.
Dysfunction can lead to ammonia buildup, which affects the central nervous system.
Nurses must recognize symptoms of encephalopathy and monitor BUN, ammonia, and liver function tests (LFTs).
Low-protein diet and medications (lactulose, antibiotics) may be required in liver disease.

🧬 Uric Acid Formation.

🔹 What is Uric Acid?

Uric acid is a nitrogenous waste product formed from the breakdown of purine nucleotides (adenine and guanine), which are components of DNA and RNA. It is the end product of purine metabolism in humans and is excreted primarily through the kidneys.

🧪 Source of Purines (Origin of Uric Acid)

Endogenous (internal) sources:
- Natural turnover of body cells
- Breakdown of nucleic acids (DNA and RNA)
- From tissues like liver, bone marrow, and intestines
Exogenous (external) sources:
- Dietary purines from foods like meat, liver, seafood, beans, mushrooms, and alcohol

🔄 Biochemical Pathway of Uric Acid Formation

🧾 Step-by-step Pathway:

Step	Compound Involved	Enzyme	Description
1.	Purine nucleotides (adenine, guanine)	—	Released during cell turnover or food digestion
2.	Adenine → Hypoxanthine	Multiple steps
3.	Guanine → Xanthine	Guanine deaminase
4.	Hypoxanthine → Xanthine	Xanthine oxidase	Intermediate step
5.	Xanthine → Uric Acid	Xanthine oxidase	Final step of uric acid production

✅ End product = Uric Acid

🔹 Excretion of Uric Acid

~70% excreted through the kidneys (urine)
~30% excreted via intestines (broken down by bacteria)

⚠️ Clinical Significance of Uric Acid

🔴 Normal Serum Uric Acid Levels:

Men: 3.4 – 7.0 mg/dL
Women: 2.4 – 6.0 mg/dL

🔴 Hyperuricemia (↑ Uric Acid)

Cause	Conditions Associated
Overproduction of uric acid	Gout, leukemia, tumor lysis syndrome
Underexcretion by kidneys	Chronic kidney disease, dehydration
High-purine diet/alcohol	Organ meats, shellfish, beer

🔍 Clinical Manifestations:

Gout: Sharp uric acid crystals deposit in joints → swelling, redness, pain (especially big toe)
Kidney stones: Uric acid crystallizes in renal tubules
Tumor lysis syndrome: Rapid cell breakdown (e.g., after chemotherapy) causes sudden uric acid surge

💊 Management of Hyperuricemia

Aspect	Intervention
Dietary advice	Low-purine diet, avoid red meat, shellfish, alcohol
Hydration	Encouraged to promote uric acid excretion
Medications	Allopurinol (↓ uric acid production), Febuxostat, Colchicine
Nursing monitoring	Joint swelling, pain, kidney function, uric acid level

🧠 Nursing Implications

Monitor uric acid levels in patients with renal disorders, gout, or cancer therapy.
Educate patients on lifestyle and diet to prevent gout attacks.
Ensure adequate hydration, especially in bedridden or elderly patients.
Watch for signs of joint inflammation and renal colic.

✅ Quick Summary Chart

Topic	Details
Main Source	Purine metabolism (adenine, guanine)
Key Enzyme	Xanthine oxidase
End Product	Uric acid (excreted in urine)
High Levels Cause	Gout, kidney stones, tumor lysis syndrome
Nursing Role	Monitor labs, advise diet, ensure hydration, watch symptoms

🦴 GOUT – Clinical and Academic Details

🔹 Definition

Gout is a metabolic disorder characterized by recurrent attacks of acute inflammatory arthritis due to deposition of monosodium urate (MSU) crystals in joints and surrounding tissues, resulting from elevated uric acid levels (hyperuricemia) in the blood.

🔹 Types of Gout

Type	Description
Acute Gout	Sudden, severe joint pain with swelling and redness
Chronic Tophaceous Gout	Long-standing condition with tophi (crystal deposits in tissues)
Asymptomatic Hyperuricemia	High uric acid without symptoms
Intercritical Gout	Symptom-free period between attacks

🔹 Causes of Gout

1. Increased Uric Acid Production

High-purine diet (red meat, seafood)
Excessive alcohol (especially beer)
Obesity and metabolic syndrome
Hematologic malignancies (leukemia, lymphoma)
Chemotherapy (tumor lysis syndrome)

2. Decreased Uric Acid Excretion

Chronic kidney disease
Diuretic use (thiazides, loop diuretics)
Dehydration
Lead poisoning

🔹 Risk Factors

Male gender (common between 30–50 years)
Family history of gout
High alcohol intake
High-purine diet
Hypertension, diabetes, renal insufficiency

🔹 Pathophysiology of Gout

Purines are broken down into uric acid.
Excess uric acid in the blood leads to supersaturation.
Uric acid crystallizes and deposits in joints, tendons, and tissues.
Crystals trigger intense inflammation → pain, redness, swelling.
Chronic inflammation leads to joint destruction and tophi formation.

🔹 Commonly Affected Joints

Big toe (1st metatarsophalangeal joint) – classic
Ankles, knees, fingers, elbows, wrists

🔹 Signs and Symptoms

Symptom	Description
Sudden severe joint pain	Often at night, wakes patient from sleep
Redness and swelling	In affected joint
Warmth and tenderness	Area feels hot and painful
Tophi formation	Hard nodules under skin (in chronic gout)
Restricted joint movement	Due to pain and inflammation
Fever	Sometimes in acute attacks

🔬 Diagnostic Investigations

Test	Findings
Serum uric acid	>7 mg/dL in men, >6 mg/dL in women
Joint fluid aspiration	Presence of needle-shaped monosodium urate crystals
X-ray of affected joint	Erosions, tophi in chronic cases
24-hour urine uric acid	To assess overproduction vs underexcretion
CBC/ESR/CRP	Elevated inflammatory markers in acute phase

💊 Medical Management

🔹 Acute Gout Attack

Medication	Purpose
NSAIDs (e.g., Indomethacin)	Reduce pain and inflammation
Colchicine	Stops neutrophil activity (used within 36 hours)
Corticosteroids (e.g., Prednisone)	For patients who can’t tolerate NSAIDs
Rest, Ice, Elevation	Reduce swelling and pain

🔹 Long-Term Management / Prevention

Medication	Action
Allopurinol	Inhibits xanthine oxidase → ↓ uric acid production
Febuxostat	Alternative xanthine oxidase inhibitor
Probenecid	Increases uric acid excretion (uricosuric drug)
Lifestyle changes	Low-purine diet, weight loss, hydration

🍗 Dietary Recommendations

To Avoid	Recommended
Red meat, organ meats, shellfish	Low-fat dairy, vegetables, whole grains
Alcohol (especially beer)	Plenty of water (2–3 liters/day)
Sugary drinks, fructose	Coffee (in moderation)

🧠 Complications

Complication	Description
Tophi	Deposits of urate crystals in tissues
Joint deformities	Chronic inflammation destroys cartilage & bone
Kidney stones	Uric acid crystals form stones
Chronic kidney disease	From long-standing hyperuricemia

👩‍⚕️ Nursing Management of Gout

Area	Nursing Interventions
Pain Management	Administer NSAIDs/Colchicine as ordered, use ice, rest joint
Monitoring	Check serum uric acid, renal function, pain level
Diet Education	Explain low-purine diet, hydration importance
Medication Compliance	Educate on regular use of maintenance drugs
Prevent Recurrence	Encourage weight loss, alcohol reduction, stress avoidance
Mobility Support	Assist with movement during attacks to avoid strain

✅ Key Points for Exams and Practice

Gout is a metabolic disorder due to hyperuricemia.
Big toe is the most common site (Podagra).
Xanthine oxidase is the key enzyme in uric acid formation.
Colchicine is effective in acute attacks if given early.
Allopurinol is used long-term, not during an acute attack.
Nurses must focus on education, pain relief, monitoring, and lifestyle support.

Published April 7, 2025By mynursingapp

Categorized as PBBBS.BIOCHEM NOTES, Uncategorised

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