Chapter 2 · Domain II, Part 1 — Screening, Assessment and Diagnosis

Domain II, Nutrition Care for Individuals and Groups, is 45% of the exam — the largest domain by far. It follows the Nutrition Care Process (NCP), the Academy of Nutrition and Dietetics' four-step framework: (1) nutrition assessment, (2) nutrition diagnosis, (3) nutrition intervention, (4) nutrition monitoring and evaluation. Screening comes before step 1 and decides who enters the process. This chapter covers CDR's Topics II.A (screening and assessment) and II.B (diagnosis); Chapter 3 covers II.C (planning and intervention) and II.D (monitoring and evaluation). Questions from this domain are usually short patient scenarios that ask what the data mean or what to do next.

II.A · Screening and Assessment

II.A.1 · Nutrition screening

Purpose. Screening is a quick, inexpensive way to identify people who are malnourished or at nutrition risk, so that the dietitian's time goes to those who need a full assessment. Screening is not assessment and does not produce a diagnosis; a positive screen triggers a referral for assessment, and a negative screen triggers rescreening at a set interval.

Selection of risk factors and evidence-based tools. A good screening tool is valid for the population in which it is used, quick, and usable by trained non-dietitian staff (nurses on admission, for instance). Commonly used tools:

• Malnutrition Screening Tool (MST) — two questions (recent unintentional weight loss and poor intake from decreased appetite), designed for hospitalized patients.
• Malnutrition Universal Screening Tool (MUST) — BMI, unintentional weight loss and the effect of acute illness.
• Mini Nutritional Assessment (MNA) — a screening and assessment tool validated for older adults (65 and older).

Parameters and limitations. Screening favors sensitivity: missing a malnourished patient costs more than sending a well-nourished one for an assessment that clears them. No single parameter is enough. Unintentional loss of 10% or more of usual body weight over 3 months signals a high probability of undernutrition — a far stronger finding than one low albumin value.

Interdisciplinary teams, cultural competence and prioritizing risk. Nurses usually complete admission screens; the dietitian designs or selects the tool, trains staff, sets the referral criteria and audits completion. Screening questions must work across languages and food cultures ("Have you been eating less than usual?" works; a list of "typical" American foods may not). When several patients screen positive, the dietitian prioritizes by severity and acuity: a patient with rapid weight loss and no intake for five days is seen before a stable patient with a BMI of 19.

II.A.2 · Nutrition assessment of individuals

Nutrition assessment is a systematic process of obtaining, verifying and interpreting data to decide whether a nutrition problem exists, what it is, and what is causing it. The data fall into the familiar domains: food and nutrition history, anthropometrics, biochemical data and medical tests, nutrition-focused physical findings, and client history.

Dietary intake assessment.

Compare intake with estimated needs, and look at pattern and context: meal timing, who shops and cooks, food access, cultural and religious practices, chewing and swallowing, and supplements.

Medical and family history. Diagnoses, surgeries (for example, gastric bypass or ileal resection), treatments such as chemotherapy, and family history of cardiovascular disease or diabetes shape both risk and recommendations.

Anthropometric data. Measured height and weight beat stated values. For adults 20 and older, CDC's BMI categories are: underweight below 18.5; healthy weight 18.5 to below 25; overweight 25 to below 30; obesity 30 or greater (class 1, 30 to below 35; class 2, 35 to below 40; class 3, 40 or greater). For children and teens 2–19, BMI is plotted as a percentile for age and sex: underweight below the 5th percentile; healthy weight 5th to below 85th; overweight 85th to below 95th; obesity at or above the 95th percentile. A waist circumference above 35 inches in women or above 40 inches in men increases risk. The single most useful weight datum is usually the percent weight change: (usual weight − current weight) ÷ usual weight × 100. A patient whose usual weight was 80 kg and who now weighs 70 kg has lost 12.5%.

Nutrition-focused physical exam (NFPE). Look for loss of subcutaneous fat (orbital, triceps, ribs) and muscle (temples, clavicles, shoulders, interosseous muscles of the hand, thighs, calves), fluid accumulation (edema, ascites) that can mask weight loss, reduced handgrip strength, and micronutrient signs in skin, hair, eyes, mouth and nails. Intake and output records show fluid balance and losses from drains, fistulas, vomiting or diarrhea.

Medication management. Record prescription and over-the-counter drugs and supplements, and screen for interactions:

• Warfarin and vitamin K — keep vitamin K intake consistent.
• Grapefruit juice blocks the intestinal enzyme CYP3A4 that breaks down some drugs (including some statins, such as simvastatin and atorvastatin), so more drug enters the blood and stays in the body longer.
• Metformin can lower vitamin B12 absorption; proton pump inhibitors also reduce B12 status.
• MAO inhibitors and tyramine-rich foods (aged cheeses, cured meats) can provoke a hypertensive crisis.
• Levothyroxine absorption is reduced when taken with calcium or iron supplements or a meal.

Biochemical data, diagnostic tests and procedures. Laboratory values must be read in clinical context. Serum albumin is inexpensive and predicts morbidity and mortality, but it has not been shown to be a reliable indicator of nutritional status: inflammation drives albumin and the other "nutritional" proteins down regardless of intake. Albumin falls slowly; prealbumin (transthyretin), transferrin and retinol-binding protein fall faster in starvation. Glycemia: an HbA1c of 6.5% or above, a fasting plasma glucose of 126 mg/dL or above, or a 2-hour oral glucose tolerance result of 200 mg/dL or above is in the diabetes range; an HbA1c of 5.7–6.4% is prediabetes.

Energy and nutrient requirements. Measure when you can (indirect calorimetry); otherwise estimate. The Mifflin-St Jeor equation estimates resting energy expenditure (REE):

• Men: REE = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (y) + 5
• Women: REE = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (y) − 161

In its derivation study the older Harris-Benedict equations overestimated measured REE by about 5%. Multiply REE by an activity (or stress) factor to estimate total needs. Protein for healthy adults is 0.8 g/kg/day (the RDA) and higher in catabolic states.

Physical activity habits, comparative standards and wellness. Physical activity changes energy needs and is part of every assessment. Comparative standards — the DRIs, growth charts, estimated requirements — are the yardsticks against which intake and growth are judged.

Economic, social and functional factors, and educational readiness. Income, housing, food access, transportation, social support, the ability to shop and cook, and dexterity to self-feed are assessment data, not background. So is readiness to change (stage of change), educational level and learning preferences — they determine whether the intervention can work.

II.A.3 · Nutrition assessment of populations and community needs assessment

Status indicators. Demographic data, the incidence and prevalence of nutrition-related conditions, and the prevalence of food insecurity describe a community. USDA's Economic Research Service defines low food security as reports of reduced quality, variety or desirability of diet with little or no indication of reduced food intake, and very low food security as reports of multiple indications of disrupted eating patterns and reduced food intake.

National surveillance systems.

• NHANES (National Health and Nutrition Examination Survey, CDC/NCHS) is the only national health survey that combines health examinations, laboratory tests and dietary interviews for participants of all ages — the source of national data on nutrient intake and biochemical status.
• BRFSS (Behavioral Risk Factor Surveillance System) is a system of state-based telephone surveys of adults' health-related risk behaviors, chronic conditions and use of preventive services — the source for state-level estimates.
• YRBSS (Youth Risk Behavior Surveillance System) monitors health behaviors among high-school students.

Community resources — know who each program serves.

II.B · Diagnosis

II.B.1 · Relationship between nutrition diagnoses and medical diagnoses

A medical diagnosis names a disease or pathology (type 2 diabetes, chronic kidney disease). A nutrition diagnosis names a nutrition problem that the dietitian is responsible for treating and can resolve or improve (excessive carbohydrate intake, inadequate protein-energy intake, swallowing difficulty). The medical diagnosis often explains why the nutrition problem exists and may appear in the etiology — but "type 2 diabetes" is never itself a nutrition diagnosis, and a nutrition diagnosis can resolve while the disease persists. For groups, the same logic applies: "inadequate calcium intake among adolescent girls in the district" is a population nutrition diagnosis.

II.B.2 · Data sources and standardized language

Diagnosis organizes assessment data into clusters and names the problem with standardized Nutrition Care Process Terminology, grouped in three domains:

• Intake — too much or too little of energy, fluid, bioactive substances or nutrients compared with needs (for example, excessive energy intake, inadequate fiber intake).
• Clinical — nutrition problems related to medical or physical conditions: functional changes (swallowing difficulty), biochemical changes (altered nutrition-related laboratory values), and weight (unintended weight loss, obesity).
• Behavioral-environmental — knowledge, attitudes and beliefs; physical activity and function (including self-feeding ability); and food access and safety.

When a problem could be written in more than one domain, an intake diagnosis is usually preferred, because it is the most specific to what the dietitian can change; behavioral-environmental problems often fit better as the etiology.

II.B.3 · Diagnosing nutrition problems for individuals and groups

The dietitian makes inferences from clustered data, prioritizes (safety first: aspiration risk, refeeding risk, severe malnutrition), and differentially diagnoses — rules out alternatives. A patient with a low sodium level and weight gain may have fluid excess rather than inadequate sodium intake; the assessment data must fit the diagnosis chosen. Choose the diagnosis your intervention will actually target: if the plan focuses on saturated fat, "inadequate fiber intake" can wait for another encounter.

II.B.4 · Etiologies

The etiology is the root cause or contributing risk factor of the problem, linked with "related to." It should be the most specific cause that a nutrition intervention can resolve or improve — "related to lack of knowledge of carbohydrate sources" is actionable; "related to diabetes" is not. If the root cause cannot be changed by the dietitian (for example, a chemotherapy regimen), the intervention targets the signs and symptoms instead.

II.B.5 · Signs and symptoms

Signs and symptoms are the evidence, linked with "as evidenced by." Signs are objective (weight, laboratory values, measured intake); symptoms are subjective (reported nausea, early satiety). They must be specific and measurable so that the dietitian can later tell whether the problem has resolved — they become the monitoring indicators in step 4.

II.B.6 · Documentation

The PES statement is written: Problem related to Etiology as evidenced by Signs and symptoms. Example: "Excessive energy intake related to unchanged dietary intake and restricted mobility while a fracture heals as evidenced by 5 lb weight gain over 3 weeks and reported intake of about 500 kcal/day above estimated needs." Charting commonly follows the ADIME format (Assessment, Diagnosis, Intervention, Monitoring/Evaluation), which mirrors the NCP. Notes are objective and quantified ("ate 25% of lunch") rather than impressionistic ("poor appetite").