Pathology of Nutritional Disorders

Introduction

Nutritional disorders remain a significant global health issue, affecting individuals across all age groups and socioeconomic backgrounds. For nursing professionals, a thorough understanding of the pathology and genetics underlying these disorders is essential for effective patient care, education, and advocacy.

The interplay between nutrition, pathology, and genetics is complex and multifaceted. Nutritional status influences disease progression, while genetic predisposition can affect nutrient metabolism and risk of certain disorders. As frontline healthcare providers, nurses play a pivotal role in recognising the signs and symptoms of nutritional disorders, implementing appropriate interventions, and collaborating with multidisciplinary teams to optimise patient outcomes.

Basics of Nutrition

Macronutrients

Macronutrients are nutrients required in large amounts to sustain life and health. They include carbohydrates, proteins, and fats:

• Carbohydrates: Primary source of energy; found in cereals, fruits, vegetables, and sugars.
• Proteins: Essential for tissue growth, repair, and enzyme production; found in pulses, meat, dairy, and legumes.
• Fats: Provide energy, aid in absorption of fat-soluble vitamins, and are vital for cell membrane integrity; sourced from oils, nuts, and animal products.

Micronutrients

Micronutrients are vitamins and minerals required in smaller quantities but are crucial for various physiological functions:

• Vitamins: Organic compounds like vitamin A, D, B12, and C are vital for vision, bone health, nerve function, and immunity.
• Minerals: Inorganic elements such as iron, iodine, and calcium are essential for haemoglobin formation, thyroid function, and bone strength.

Role in Health

Balanced nutrition supports growth, development, immune function, and disease prevention. Deficiency or excess of nutrients can disrupt physiological processes, leading to a spectrum of nutritional disorders.

Overview of Nutritional Disorders

Classification

Nutritional disorders are generally classified based on the nature of nutrient imbalance:

• Deficiency Disorders: Result from inadequate intake or absorption of essential nutrients (e.g., iron deficiency anaemia, scurvy).
• Excess Disorders: Caused by overconsumption of nutrients (e.g., obesity, hypervitaminosis A).
• Imbalance Disorders: Occur due to disproportionate nutrient intake (e.g., metabolic syndrome).

General Causes

Common causes of nutritional disorders include:

• Poor dietary habits or food insecurity
• Malabsorption syndromes (e.g., coeliac disease)
• Chronic illnesses (e.g., cancer, renal disease)
• Genetic factors affecting metabolism
• Socioeconomic and cultural influences

Pathology of Common Nutritional Disorders

Protein-Energy Malnutrition (PEM)

Kwashiorkor

Kwashiorkor is a severe form of protein deficiency, typically seen in children after weaning. It is characterised by oedema, fatty liver, skin changes, and stunted growth. The lack of dietary protein leads to hypoalbuminaemia, resulting in fluid leakage into tissues (oedema). Immune function is impaired, increasing susceptibility to infections.

Marasmus

Marasmus results from a general deficiency of both calories and protein. It manifests as severe wasting, muscle atrophy, and loss of subcutaneous fat. Unlike kwashiorkor, oedema is absent. The body utilises its own tissues for energy, leading to emaciation and weakened immunity.

Vitamin Deficiencies

• Vitamin A Deficiency: Causes night blindness, xerophthalmia, and increased risk of infections. Pathologically, it leads to keratinisation of epithelial tissues and impaired immune response.
• Vitamin D Deficiency: Results in rickets (children) and osteomalacia (adults), due to impaired calcium absorption and defective bone mineralisation.
• Vitamin B12 Deficiency: Causes megaloblastic anaemia and neurological symptoms due to impaired DNA synthesis and myelin formation.
• Vitamin C Deficiency: Leads to scurvy, characterised by defective collagen synthesis, bleeding gums, and poor wound healing.

Mineral Deficiencies

• Iron Deficiency: Most common cause of anaemia. Pathology includes reduced haemoglobin synthesis and microcytic hypochromic anaemia.
• Iodine Deficiency: Causes goitre and hypothyroidism. In children, it can lead to cretinism, with irreversible mental and physical retardation.
• Calcium Deficiency: Results in poor bone mineralisation, leading to osteoporosis and increased fracture risk.

Obesity

Obesity is defined as excessive fat accumulation that impairs health. It is a multifactorial disorder involving environmental, behavioural, and genetic factors. Pathologically, obesity is associated with chronic low-grade inflammation, insulin resistance, dyslipidaemia, and increased risk of cardiovascular disease, diabetes, and certain cancers.

Metabolic Syndrome

Metabolic syndrome is a cluster of conditions including central obesity, hypertension, dyslipidaemia, and insulin resistance. It increases the risk of type 2 diabetes and cardiovascular disease. The underlying pathology involves abnormal fat distribution, impaired glucose metabolism, and chronic inflammation.

Genetic Aspects of Nutritional Disorders

Genetic factors play a crucial role in the susceptibility and manifestation of several nutritional disorders. Understanding these aspects is vital for early detection, targeted interventions, and genetic counselling.

Inherited Metabolic Disorders

• Phenylketonuria (PKU): An autosomal recessive disorder caused by mutations in the PAH gene, leading to deficiency of the enzyme phenylalanine hydroxylase. This results in accumulation of phenylalanine, which is toxic to the brain. Early dietary intervention can prevent intellectual disability.
• Galactosaemia: A group of inherited disorders affecting galactose metabolism. Classic galactosaemia (GALT deficiency) causes accumulation of galactose-1-phosphate, leading to liver damage, cataracts, and cognitive impairment if untreated.
• Wilson’s Disease: An autosomal recessive disorder caused by mutations in the ATP7B gene, leading to defective copper transport and accumulation in the liver, brain, and other organs. Symptoms include liver dysfunction, neurological disturbances, and psychiatric manifestations.

Genetic Predispositions to Obesity and Diabetes

Obesity and type 2 diabetes are complex, multifactorial disorders with strong genetic components. Specific gene variants (e.g., FTO, MC4R) influence appetite, energy expenditure, and fat storage. While lifestyle factors are crucial, genetic predisposition can increase individual susceptibility, making prevention and management more challenging.

Clinical Features and Diagnosis

Signs and Symptoms

Nutritional disorders present with a wide range of clinical features depending on the specific nutrient involved:

• General: Fatigue, weight loss or gain, weakness, poor growth in children
• Skin and Hair: Dry, scaly skin; hair loss; dermatitis
• Gastrointestinal: Diarrhoea, glossitis, cheilosis
• Haematological: Anaemia, easy bruising
• Neurological: Peripheral neuropathy, cognitive impairment
• Musculoskeletal: Bone pain, fractures, muscle cramps
• Ocular: Night blindness, Bitot’s spots

Laboratory Investigations

Diagnosis of nutritional disorders involves a combination of clinical assessment and laboratory investigations:

• Blood tests: Complete blood count, serum vitamin and mineral levels, liver and renal function tests
• Urine analysis: For abnormal metabolites (e.g., in PKU and galactosaemia)
• Imaging: Bone density scans (for osteoporosis), ultrasound (for fatty liver)
• Genetic testing: For inherited metabolic disorders and risk assessment

Differential Diagnosis

It is important to differentiate nutritional disorders from other medical conditions with similar presentations, such as chronic infections, malignancies, and autoimmune diseases. A detailed history, thorough examination, and appropriate investigations aid in accurate diagnosis.

Management and Treatment

Dietary Interventions

The cornerstone of managing most nutritional disorders is dietary modification:

• Protein-energy malnutrition: High-protein, high-calorie diets; therapeutic feeds
• Vitamin and mineral deficiencies: Supplementation and dietary diversification
• Obesity and metabolic syndrome: Calorie restriction, balanced diets, increased physical activity
• Inherited metabolic disorders: Specialised diets (e.g., low-phenylalanine for PKU, lactose-free for galactosaemia)

Supplementation and Pharmacological Approaches

Oral or parenteral supplementation is indicated in cases of severe deficiency. Medications may be required for associated conditions (e.g., antihypertensives in metabolic syndrome, chelating agents for Wilson’s disease).

Genetic Counselling

For inherited metabolic disorders, genetic counselling is essential for affected families. It provides information on inheritance patterns, recurrence risk, and reproductive options.

Nursing Implications for Nutritional Disorders

Assessment

Nurses must conduct comprehensive nutritional assessments, including dietary history, anthropometric measurements (weight, height, BMI, mid-arm circumference), and identification of risk factors.

Patient Education

Education is a key nursing role. Nurses should educate patients and families on:

• Importance of balanced nutrition
• Recognition of early signs and symptoms
• Dietary modifications and adherence to prescribed regimens
• Potential complications and when to seek medical attention

Monitoring and Follow-up

Ongoing monitoring of nutritional status, laboratory parameters, and response to treatment is vital. Nurses should be vigilant for signs of complications and ensure timely interventions.

Multidisciplinary Collaboration

Optimal management of nutritional disorders requires collaboration with dietitians, physicians, physiotherapists, and social workers. Nurses are central in coordinating care and facilitating communication among team members.

Case Studies about Nutritional Disorders

Case Study 1: Kwashiorkor in a 3-Year-Old Child

A 3-year-old child from a rural area presents with oedema, irritability, and skin lesions. Dietary history reveals early weaning onto a carbohydrate-rich, protein-poor diet. Laboratory tests show hypoalbuminaemia. The child is diagnosed with kwashiorkor. Nursing interventions include initiating therapeutic feeds, monitoring fluid balance, and educating caregivers on balanced nutrition.

Case Study 2: Vitamin D Deficiency in an Elderly Woman

A 65-year-old woman presents with bone pain and frequent fractures. She has limited sun exposure and a vegetarian diet low in fortified foods. Investigations show low serum vitamin D and reduced bone mineral density. Management involves vitamin D and calcium supplementation, dietary advice, and fall prevention strategies. Nurses play a key role in patient education and monitoring adherence.

Case Study 3: Phenylketonuria (PKU) in a Newborn

A newborn is identified through routine screening to have elevated phenylalanine levels. Genetic testing confirms PKU. Early dietary intervention with a low-phenylalanine formula is initiated. The nurse educates parents about lifelong dietary management and regular monitoring to prevent intellectual disability.

REFERENCES

1. Ramadas Nayak, Textbook of Pathology and Genetics for Nurses, 2nd Edition,2024, Jaypee Publishers, ISBN: 978-93-5270-031-8.
2. Suresh Sharma, Textbook of Pharmacology, Pathology & Genetics for Nurses II, 2nd Edition, 31 August 2022, Jaypee Publishers, ISBN: 978-9354655692.
3. Kumar, V., Abbas, A.K., & Aster, J.C. (2020). Robbins and Cotran Pathologic Basis of Disease. 10th Edition. Elsevier.
4. McCance, K.L., & Huether, S.E. (2018). Pathophysiology: The Biologic Basis for Disease in Adults and Children. 8th Edition. Elsevier.
5. Stare FJ. The Pathology of Nutritional Disease. Am J Public Health Nations Health. 1948 Jun;38(6):880–1. PMCID: PMC1624455. https://pmc.ncbi.nlm.nih.gov/articles/PMC1624455/
6. The Pathology of Nutritional Disease: Physiological and Morphological Changes Which Result from Deficiences of the Essential Elements, Amino Acids, Vitamins, and Fatty Acids. JAMA. 1948;138(4):327. doi:10.1001/jama.1948.02900040071028

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