Nutritional Assessment and Biochemical Testing
What the exam tests
This domain tests nutrition assessment: interview, anthropometrics, dietary intake methods, biochemical testing, interpretation limits, and referral.
Core rules
- Common dietary assessment tools include 24-hour recall, food frequency questionnaire, food records, and diet history; each has recall bias and underreporting limitations.
- Anthropometrics include weight, body mass index, waist circumference, and body composition; trends matter more than single measurements.
- Useful biochemical tests include CBC, comprehensive metabolic panel, lipid panel, HbA1c, TSH, vitamin D, vitamin B12, ferritin, and CRP, chosen for the clinical question.
- Reference ranges describe population distributions, not necessarily optimal health; fasting status, medications, inflammation, and hydration affect results.
- Do not diagnose from labs; share findings and refer for medical interpretation.
Worked example
A client has low ferritin but normal hemoglobin. Reasoning: this suggests iron deficiency without anemia. Assess dietary iron, absorption inhibitors, menstrual or gastrointestinal blood loss, and celiac risk; refer for medical evaluation rather than simply recommending iron. The reasoning is to identify cause before supplementing.
Traps
- Overinterpreting "optimal" lab ranges.
- Ignoring symptoms and trends.
- Ordering tests outside scope.
- Treating a lab value instead of a person.