| Clinical examination | Signs: pallor, Bitot's spots, angular stomatitis, goitre, oedema, hair/skin changes, rickets | Cheap, quick | Non‑specific; appear late; observer variation |
| Anthropometry | Weight, height/length, MUAC, head circumference, skinfold thickness, waist, BMI; Z‑scores | Objective, standardised, cheap | Doesn't identify specific deficiency; measurement error |
| Biochemical/laboratory | Hb, serum ferritin, retinol, urinary iodine, vitamin D, zinc, albumin, stool for parasites | Specific, early detection | Costly, invasive, inflammation effects (ferritin), lab quality |
| Functional assessment | Dark adaptation, physical work capacity, cognition | Relates to function | Complex |
| Dietary assessment | 24‑h recall, FFQ, weighment, diet history, food balance sheets | Identifies cause and intake | Recall bias, portion estimation |
| Vital and health statistics | IMR, U5MR, LBW, morbidity (diarrhoea, measles) | Population signal | Indirect |
| Ecological factors | Food production, prices, income, water, sanitation, culture, health services | Explains causes | Broad |