Examination of nutritional status (pathobiochemistry)

Calculations

• Quetelet index = BMI (body mass index) = weight in kg / (height in m) ²
• Calculation according to Harris and Benedict equations - energy expenditure at rest (REE) in kcal / day
  1. for women = 655 + 9.6 × (weight in kg) + 1.7 × (height in cm) - 4.7 × (age in years)
  2. for men = 66 + 13.7 × (weight in kg) + 5.0 × (height in cm) - 6.8 × (age in years)
  • factors influencing resting energy expenditure:
    1. Stress factors:
       • fasting: 0.85
       • surgery: 1.0–1.2
       • sepsis: 1.4–1.8
       • Fever: 1.0 + 0.13 per degree Celsius
       • peritonitis: 1.2–1.5
       • cancer: 1.1 - 1.45
    2. Physical Activity Factors:
       • patient all day in bed - 1.15
       • patient lying on the toilet - 1.20
       • patient walking around the room - 1.25
       • patient walking after ward - 1.30
  • Calculation of total energy expenditure = REE × stress × activity

Tab.: Výdej a potřeba energie u novorozenců a malých dětí

Tělesná hmotnost (v kg)	Výdej (potřeba energie) v kcal/kg/den
Do 10	100 kcal/kg
10–20	1000 kcal + 50 kcal/na každý 1 kg nad 10 kg hmotnosti
Více než 20	1500 kcal + 20 kcal/na každý 1 kg nad 20 kg hmotnosti

Energy expenditure (need) in children varies according to age and certain conditions. The average energy expenditure of a 6-12 year old child is 50% basal metabolic, 12% growth needs, 25% physical activity, 13% various losses (eg unabsorbed fat). The so-called The thermal effect of food is caused mainly by ingested proteins (30% above basal output), while fat and carbohydrates 4%. The energy supply best corresponds to the size of the body surface. However, it is possible to count about 80-120 kcal / kg of weight for the first year of life and then reduce it by 10 kcal / kg every 3 years. The period of rapid growth and development around puberty requires a proportionally higher income. Each 1 g of proteins or carbohydrates received yields 4 kcal, 1 g of short-chain fatty acids 5.3 kcal, medium-chain 8.3 and long-chain fatty acids 9 kcal.

Nutrition tests

Anthropometric tests

• weight loss - refers to total body weight
• measurement of skin lashes over:
  1. triceps
  2. shovel
  3. pelvic christ - refers to the evaluation of total fat
• measurement of the circumference around the middle part of the arm - refers to body weight without fat

Laboratory tests

• Biochemical
  1. albumin (does not fall below 35 g / l)
  2. prealbumin (does not fall below 0.10 g / l)
  3. transferrin (should not be below 1.7 g / l)
  4. IGF binding protein 3
  5. fibronectin
  6. S-Fe, Cu, Zn
  7. S-urea, dU-urea
  8. glucose
• Hematological
  • hemoglobin, hematocrit, number erythrocyte, number leukocyte, number lymphocyte, number platelet
• Immunological
  • humoral immunity (IgG, IgA, IgM)
  • cellular immunity (delayed hypersensitivity skin tests)

Calorimetry

The most objective determination of energy expenditure is examination using indirect calorimetry. However, this is not a commonly used technique. Far more is the estimate of energy expenditure by calculation based on empirical equations (see above). The device enables non-invasive monitoring of respiratory gas exchange with continuous expression of the value of oxygen consumed and carbon dioxide produced in time intervals of 1 minute.

Nitrogen balance

There is a dynamic balance between the production (anabolism) and degradation (catabolism) of tissue proteins. In healthy individuals on a balanced diet, nitrogen intake and output are in balance. Under pathological situations leading to damage to the body, after surgical procedures or during prolonged stress, a metabolic response occurs in which catabolism predominates over anabolism. A negative nitrogen balance is created. The simplest approximate calculation is obtained by comparing the N-supply contained in proteins with the N-content of urea excreted in 24 hours in the urine (dU-urea):

• N-equilibrium (in g) = (protein supply / 6,25) - (dU-urea in g) + 2,5
• Protein balance = protein intake - protein loss (= (dU-urea in g + 4) x 6.25)

Note: The body is not able to store proteins in stock, as is the case with glycogen for carbohydrates or triacylglycerols for fats. There is only a so-called amino acid pool, which is about 70-80 g in an adult, which is depleted in a few hours during starvation.

The recommended minimum intake protein per day for a 70 kg individual is 1 g / kg body weight, which corresponds to 11 g N per 24 h.

Tab. Nitrogen and protein losses in various postoperative conditions according to Frey, 1975

Surgery	N losses in 24 h (in g)	Body protein losses (in g / 24 h)
Abdominal surgery	10–18	62,5–112,5
Gastric resection	15–20	93,75–125,0
Cholecystectomy	do 15	do 93,75
Lung resection	do 22	do 137,5
Abdominal hysterectomy	6–15	37,5–93,75
Total exenteration	až 32	až 200

Links

Related Articles

• Nutritional Assessment
• Eating Disorders

Source

• ws:Vyšetření stavu výživy (patobiochemie)