- Thermic - see condition
- Thermography (abnormal) 793.9
- Thermoplegia 992.0
- Thesaurismosis
- Thiaminic deficiency 265.1
- Thibierge-Weissenbach syndrome (cutaneous systemic sclerosis) 710.1
- Thickened endometrium 793.5
- Thickening
- Thiele syndrome 724.6
- Thigh - see condition
- Thinning vertebra (see also Osteoporosis) 733.00
- Thirst, excessive 783.5
- Thomsen's disease 359.2
- Thomson's disease (congenital poikiloderma) 757.33
- Thoracic - see also condition
- Thoracogastroschisis (congenital) 759.89
- Thoracopagus 759.4
- Thoracoschisis 756.3
- Thoracoscopic surgical procedure converted to open procedure V64.42
- Thorax - see condition
- Thorn's syndrome (see also Disease, renal) 593.9
- Thornwaldt's, Tornwaldt's
