TPO

TPO can be

 Biology and medicine 
 the temporo-parieto-occipital junction of the brain
 Thyroid peroxidase (or thyroperoxidase), an enzyme in the thyroid
 Thrombopoietin, a hormone stimulating platelet growth

 Government 
 Transportation Planning Organization, United States

 Law 

 a tree preservation order in the United Kingdom

 Science and technology 
 Thermoplastic olefin, a plastic polymer/filler blend
 Transmitter power output in radio transmission
 Trimethylbenzoyl diphenylphosphine oxide, a chemical substance or chemical  

 Other 
 The People's Operator, a mobile virtual network operator in the United Kingdom
 Third-party ownership in association football
 A transit patrol officer of Victoria Transit Patrol, Australia
 Travelling Post Offices, mail trains in Great Britain and Ireland
 Travelling Post Office, Queensland, mail trains in Australia
 Treatment plant operator, an operator of water and waste water treatment plants
 Triple peel on opponent manoeuvre in croquet

 Arts 
 Taipei Philharmonic Orchestra
 Thailand Philharmonic Orchestra

 Tokyo Philharmonic Orchestra