Differentials
Hypothyroidism
SIGNS / SYMPTOMS
May be clinically difficult to differentiate.
Headaches, cold intolerance, hearing impairment, muscle cramps, modest weight gain, dry skin, eyelid oedema, thick tongue, facial oedema.
INVESTIGATIONS
Serum thyroid-stimulating hormone (TSH): elevated TSH level.
Depression
SIGNS / SYMPTOMS
May be clinically difficult to differentiate.
History of depressed mood, anhedonia, libido changes, sleep disturbance, psychomotor problems, excessive guilt, poor concentration, suicidal ideation.
INVESTIGATIONS
Clinical diagnosis.
Serum or plasma zinc levels: normal.
Iron deficiency
SIGNS / SYMPTOMS
May co-exist with cases of zinc deficiency and be difficult to differentiate clinically.
INVESTIGATIONS
FBC with peripheral smear: microcytic anaemia; pale red cells with anisopoikilocytosis (variation in size and shape) and pencil cells.
Serum iron: low.
TIBC (total iron-binding capacity): increased.
Transferrin saturation: <16%.
Serum ferritin: low.
Vitamin B12 deficiency
SIGNS / SYMPTOMS
May co-exist with cases of zinc deficiency and be difficult to differentiate clinically.
INVESTIGATIONS
FBC with peripheral smear: macrocytic anaemia; leukopenia or thrombocytopenia (severe disease); hypersegmented polymorphonucleated cells and megalocytes. May have normal haematological parameters in mild disease.
Serum vitamin B12 level: <148 pmol/L (200 picograms/mL).
Folate deficiency
SIGNS / SYMPTOMS
May co-exist with cases of zinc deficiency and be difficult to differentiate clinically.
INVESTIGATIONS
FBC with peripheral smear: macrocytic anaemia; leukopenia or thrombocytopenia (severe disease); hypersegmented polymorphonucleated cells and megalocytes. May have normal haematological parameters in mild disease.
Serum folate level: <7 nmol/L (3 nanograms/mL)
Vitamin D deficiency
SIGNS / SYMPTOMS
May co-exist with cases of zinc deficiency and be difficult to differentiate clinically.
INVESTIGATIONS
Serum 25 dihydroxyvitamin D level: low (<37.4 nmol/L [15 nanograms/mL]).
Vitamin A deficiency
SIGNS / SYMPTOMS
May co-exist with cases of zinc deficiency and be difficult to differentiate clinically.
INVESTIGATIONS
Serum vitamin A level: low.
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