O

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OCCULT BLOOD - faeces
OESOPHAGEAL BRUSHINGS/BIOPSY
OESTRADIOL - serum
OESTRIOL - serum
OESTROGEN RECEPTOR
ONCOGENE STUDIES
ORGANIC ACIDS - urine
OSMOLALITY - serum
OSMOLALITY - urine
OSMOLAR GAP
OSMOLARITY
OSMOTIC FRAGILITY - red cell
OSMOTIC GAP
OSTEOCALCIN - serum
OVA, CYSTS AND PARASITES - faeces
OVARIAN ANTIBODIES - serum
OVARIAN BIOPSY
OXALATE - urine
OXIMETRY
17-OXOSTEROIDS - urine
OXYGEN (pO2) - arterial blood
OXYGEN DISSOCIATION CURVE