Table 1.

Categorization of thyroid status at start of TRT.

Type of thyroid dysfunction	Laboratory values
Normal	Within the normal reference interval valid at the time (Appendix 1)
Hypothyroidism
Overt	TSH elevated, fT4 lowered
Subclinical	TSH elevated, fT4 normal
Low fT4 only	TSH normal, fT4 lowered
Unclassified	TSH elevated, fT4 value unknown

fT4: free serum thyroxine; TSH: thyroid-stimulating hormone; TRT: thyroid replacement therapy.