Assessment of nutritional status



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ASSESSMENT OF NUTRITIONAL STATUS

  • Abdelaziz Elamin, MD, PhD, FRCPCH
  • College of Medicine
  • Sultan Qaboos University, Oman

LEARNING OBJECTIVES

  • By the end of this lecture the reader should be able to:
  • To know the different methods for assessing the nutritional status
  • To understand the basic anthropometric techniques, applications, & reference standards

INTRODUCTION

  • The nutritional status of an individual is often the result of many inter-related factors.
  • It is influenced by food intake, quantity & quality, & physical health.
  • The spectrum of nutritional status spread from obesity to severe malnutrition

Nutritional Assessment Why?

  • The purpose of nutritional assessment is to:
  • Identify individuals or population groups
  • at risk of becoming malnourished
  • Identify individuals or population groups
  • who are malnourished

Nutritional Assessment Why? 2

  • To develop health care programs that meet the community needs which are defined by the assessment
  • To measure the effectiveness of the nutritional programs & intervention once initiated

Methods of Nutritional Assessment

  • Nutrition is assessed by two types of methods; direct and indirect.
  • The direct methods deal with the individual and measure objective criteria, while indirect methods use community health indices that reflects nutritional influences.

Direct Methods of Nutritional Assessment

  • These are summarized as ABCD
  • Anthropometric methods
  • Biochemical, laboratory methods
  • Clinical methods
  • Dietary evaluation methods

Indirect Methods of Nutritional Assessment

  • These include three categories:
  • Ecological variables including crop production
  • Economic factors e.g. per capita income, population density & social habits
  • Vital health statistics particularly infant & under 5 mortality & fertility index

CLINICAL ASSESSMENT

  • It is an essential features of all nutritional surveys
  • It is the simplest & most practical method of ascertaining the nutritional status of a group of individuals
  • It utilizes a number of physical signs, (specific & non specific), that are known to be associated with malnutrition and deficiency of vitamins & micronutrients.

CLINICAL ASSESSMENT/2

  • Good nutritional history should be obtained
  • General clinical examination, with special attention to organs like hair, angles of the mouth, gums, nails, skin, eyes, tongue, muscles, bones, & thyroid gland.
  • Detection of relevant signs helps in establishing the nutritional diagnosis

CLINICAL ASSESSMENT/3

  • ADVANTAGES
    • Fast & Easy to perform
    • Inexpensive
    • Non-invasive
  • LIMITATIONS
    • Did not detect early cases

Clinical signs of nutritional deficiency

  • HAIR
  • Spare & thin
  • Protein, zinc, biotin
  • deficiency
  • Easy to pull out
  • Protein deficiency
  • Corkscrew
  • Coiled hair
  • Vit C & Vit A
  • deficiency

Clinical signs of nutritional deficiency

  • MOUTH
  • Glossitis
  • Riboflavin, niacin, folic acid, B12 , pr.
  • Bleeding & spongy gums
  • Vit. C,A, K, folic acid & niacin
  • Angular stomatitis, cheilosis & fissured tongue
  • B 2,6,& niacin
  • leukoplakia
  • Vit.A,B12, B-complex, folic acid & niacin
  • Sore mouth & tongue
  • Vit B12,6,c, niacin ,folic acid & iron

Clinical signs of nutritional deficiency

  • EYES
  • Night blindness, exophthalmia
  • Vitamin A deficiency
  • Photophobia-blurring,
  • conjunctival inflammation
  • Vit B2 & vit A
  • deficiencies

Clinical signs of nutritional deficiency

  • NAILS
  • Spooning
  • Iron deficiency
  • Transverse lines
  • Protein deficiency

Clinical signs of nutritional deficiency

  • SKIN
  • Pallor
  • Folic acid, iron, B12
  • Follicular hyperkeratosis
  • Flaking dermatitis
  • PEM, Vit B2, Vitamin A, Zinc & Niacin
  • Pigmentation, desquamation
  • Niacin & PEM
  • Bruising, purpura
  • Vit K ,Vit C & folic acid

Clinical signs of nutritional deficiency

  • Thyroid gland
  • in mountainous areas and far from sea places Goiter is a reliable sign of iodine deficiency.

Clinical signs of nutritional deficiency

  • Joins & bones
  • Help detect signs of vitamin D deficiency (Rickets) & vitamin C deficiency (Scurvy)

Anthropometric Methods

  • Anthropometry is the measurement of body height, weight & proportions.
  • It is an essential component of clinical examination of infants, children & pregnant women.
  • It is used to evaluate both under & over nutrition.
  • The measured values reflects the current nutritional status & don’t differentiate between acute & chronic changes .

Other anthropometric Measurements

  • Mid-arm circumference
  • Skin fold thickness
  • Head circumference
  • Head/chest ratio
  • Hip/waist ratio

Anthropometry for children

  • Accurate measurement of height and weight is essential. The results can then be used to evaluate the physical growth of the child.
  • For growth monitoring the data are plotted on growth charts over a period of time that is enough to calculate growth velocity, which can then be compared to international standards

Growth Monitoring Chart

  • Percentile chart

Measurements for adults

  • Height:
  • The subject stands erect & bare footed on a stadiometer with a movable head piece. The head piece is leveled with skull vault & height is recorded to the nearest 0.5 cm.

WEIGHT MEASUREMENT

  • Use a regularly calibrated electronic or balanced-beam scale. Spring scales are less reliable.
  • Weigh in light clothes, no shoes
  • Read to the nearest 100 gm (0.1kg)

Nutritional Indices in Adults

  • The international standard for assessing body size in adults is the body mass index (BMI).
  • BMI is computed using the following formula: BMI = Weight (kg)/ Height (m²)
  • Evidence shows that high BMI (obesity level) is associated with type 2 diabetes & high risk of cardiovascular morbidity & mortality

BMI (WHO - Classification)

  • BMI < 18.5 = Under Weight
  • BMI 18.5-24.5= Healthy weight range
  • BMI 25-30 = Overweight (grade 1
  • obesity)
  • BMI >30-40 = Obese (grade 2 obesity)
  • BMI >40 =Very obese (morbid or
  • grade 3 obesity)

Waist/Hip Ratio

  • Waist circumference is measured at the level of the umbilicus to the nearest 0.5 cm.
  • The subject stands erect with relaxed abdominal muscles, arms at the side, and feet together.
  • The measurement should be taken at the end of a normal expiration.

Waist circumference

  • Waist circumference predicts mortality better than any other anthropometric measurement.
  • It has been proposed that waist measurement alone can be used to assess obesity, and two levels of risk have been identified
  • MALES FEMALE
  • LEVEL 1 > 94cm > 80cm
  • LEVEL2 > 102cm > 88cm

Waist circumference/2

  • Level 1 is the maximum acceptable waist circumference irrespective of the adult age and there should be no further weight gain.
  • Level 2 denotes obesity and requires weight management to reduce the risk of type 2 diabetes & CVS complications.

Hip Circumference

  • Is measured at the point of greatest circumference around hips & buttocks to the nearest 0.5 cm.
  • The subject should be standing and the measurer should squat beside him.
  • Both measurement should taken with a flexible, non-stretchable tape in close contact with the skin, but without indenting the soft tissue.

Interpretation of WHR

  • High risk WHR= >0.80 for females & >0.95 for males i.e. waist measurement >80% of hip measurement for women and >95% for men indicates central (upper body) obesity and is considered high risk for diabetes & CVS disorders.
  • A WHR below these cut-off levels is considered low risk.

ADVANTAGES OF ANTHROPOMETRY

  • Objective with high specificity & sensitivity
  • Measures many variables of nutritional significance (Ht, Wt, MAC, HC, skin fold thickness, waist & hip ratio & BMI).
  • Readings are numerical & gradable on standard growth charts
  • Readings are reproducible.
  • Non-expensive & need minimal training

Limitations of Anthropometry

    • Inter-observers errors in measurement
    • Limited nutritional diagnosis
    • Problems with reference standards, i.e. local versus international standards.
    • Arbitrary statistical cut-off levels for what considered as abnormal values.

DIETARY ASSESSMENT

  • Nutritional intake of humans is assessed by five different methods. These are:
    • 24 hours dietary recall
    • Food frequency questionnaire
    • Dietary history since early life
    • Food dairy technique
    • Observed food consumption

24 Hours Dietary Recall

  • A trained interviewer asks the subject to recall all food & drink taken in the previous 24 hours.
  • It is quick, easy, & depends on short-term memory, but may not be truly representative of the person’s usual intake

Food Frequency Questionnaire

  • In this method the subject is given a list of around 100 food items to indicate his or her intake (frequency & quantity) per day, per week & per month.
  • inexpensive, more representative & easy to use.

Food Frequency Questionnaire/2

  • Limitations:
  • long Questionnaire
  • Errors with estimating serving size.
  • Needs updating with new commercial food products to keep pace with changing dietary habits.

DIETARY HISTORY

  • It is an accurate method for assessing the nutritional status.
  • The information should be collected by a trained interviewer.
  • Details about usual intake, types, amount, frequency & timing needs to be obtained.
  • Cross-checking to verify data is important.

FOOD DAIRY

  • Food intake (types & amounts) should be recorded by the subject at the time of consumption.
  • The length of the collection period range between 1-7 days.
  • Reliable but difficult to maintain.

Observed Food Consumption

  • The most unused method in clinical practice, but it is recommended for research purposes.
  • The meal eaten by the individual is weighed and contents are exactly calculated.
  • The method is characterized by having a high degree of accuracy but expensive & needs time & efforts.

Interpretation of Dietary Data

  • 1. Qualitative Method
  • using the food pyramid & the basic food groups method.
  • Different nutrients are classified into 5 groups (fat & oils, bread & cereals, milk products, meat-fish-poultry, vegetables & fruits)
  • determine the number of serving from each group & compare it with minimum requirement.

Interpretation of Dietary Data/2

  • 2. Quantitative Method
  • The amount of energy & specific nutrients in each food consumed can be calculated using food composition tables & then compare it with the recommended daily intake.
  • Evaluation by this method is expensive & time consuming, unless computing facilities are available.

Initial Laboratory Assessment

  • Hemoglobin estimation is the most important test, & useful index of the overall state of nutrition. Beside anemia it also tells about protein & trace element nutrition.
  • Stool examination for the presence of ova and/or intestinal parasites
  • Urine dipstick & microscopy for albumin, sugar and blood

Specific Lab Tests

  • Measurement of individual nutrient in body fluids (e.g. serum retinol, serum iron, urinary iodine, vitamin D)
  • Detection of abnormal amount of metabolites in the urine (e.g. urinary creatinine/hydroxyproline ratio)
  • Analysis of hair, nails & skin for micro-nutrients.

Advantages of Biochemical Method

  • It is useful in detecting early changes in body metabolism & nutrition before the appearance of overt clinical signs.
  • It is precise, accurate and reproducible.
  • Useful to validate data obtained from dietary methods e.g. comparing salt intake with 24-hour urinary excretion.

Limitations of Biochemical Method

  • Time consuming
  • Expensive
  • They cannot be applied on large scale
  • Needs trained personnel & facilities


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